Instruction Manual

Model 4500 series

Vibrating Wire Piezometers

No part of this instruction manual may be reproduced, by any means, without the written consent of Geokon, Inc.

The information contained herein is believed to be accurate and reliable. However, Geokon, Inc. assumes no responsibility for

errors, omissions or misinterpretation. The information herein is subject to change without notification.

Copyright © 1983, 1996, 2002, 2004, 2005, 2007, 2008, 2009,2011 by Geokon, Inc.

(Doc Rev V 3/11)

Warranty Statement

Geokon, Inc. warrants its products to be free of defects in materials and workmanship, under normal

use and service for a period of 13 months from date of purchase. If the unit should malfunction, it must

be returned to the factory for evaluation, freight prepaid. Upon examination by Geokon, if the unit is

found to be defective, it will be repaired or replaced at no charge. However, the WARRANTY is VOID

if the unit shows evidence of having been tampered with or shows evidence of being damaged as a

result of excessive corrosion or current, heat, moisture or vibration, improper specification,

misapplication, misuse or other operating conditions outside of Geokon's control. Components which

wear or which are damaged by misuse are not warranted. This includes fuses and batteries.

Geokon manufactures scientific instruments whose misuse is potentially dangerous. The instruments

are intended to be installed and used only by qualified personnel. There are no warranties except as

stated herein. There are no other warranties, expressed or implied, including but not limited to the

implied warranties of merchantability and of fitness for a particular purpose. Geokon, Inc. is not

responsible for any damages or losses caused to other equipment, whether direct, indirect, incidental,

special or consequential which the purchaser may experience as a result of the installation or use of the

product. The buyer's sole remedy for any breach of this agreement by Geokon, Inc. or any breach of any

warranty by Geokon, Inc. shall not exceed the purchase price paid by the purchaser to Geokon, Inc. for

the unit or units, or equipment directly affected by such breach. Under no circumstances will Geokon

reimburse the claimant for loss incurred in removing and/or reinstalling equipment.

Every precaution for accuracy has been taken in the preparation of manuals and/or software, however,

Geokon, Inc. neither assumes responsibility for any omissions or errors that may appear nor assumes

liability for any damages or losses that result from the use of the products in accordance with the

information contained in the manual or software.

TABLE of CONTENTS

1. THEORY OF OPERATION...................................................................................................................1

2. INSTALLATION .....................................................................................................................................2

2.1 PRELIMINARY TESTS .............................................................................................................................2 2.1.1 Establishing an Initial Zero Reading..............................................................................................4 2.1.2 Checking the Calibration ...............................................................................................................5

2.2 INSTALLATION IN STANDPIPES OR WELLS .............................................................................................5 2.3 INSTALLATION IN BOREHOLES...............................................................................................................6 2.4 INSTALLATION IN FILLS AND EMBANKMENTS .......................................................................................8 2.5 INSTALLATION BY PUSHING OR DRIVING INTO SOFT SOILS ...................................................................9 2.6 DE-AIRING FILTER TIPS .......................................................................................................................10

2.6.1 Low Air Entry Filter, Model 4500S and 4500PN ........................................................................10 2.6.2 Removable Ceramic Filter, Model 4500S ...................................................................................11 2.6.3 Model 4500DP ............................................................................................................................12

2.7 MODEL 4500H TRANSDUCER ..............................................................................................................12 2.8 SPLICING AND JUNCTION BOXES .........................................................................................................12 2.9 LIGHTNING PROTECTION .....................................................................................................................13

3. TAKING READINGS............................................................................................................................14

3.1 OPERATION OF THE GK-401 READOUT BOX .......................................................................................14 3.2 OPERATION OF THE GK-403 READOUT BOX .......................................................................................15 3.3 OPERATION OF THE GK404 READOUT BOX.........................................................................................15 3.4 MEASURING TEMPERATURES ..............................................................................................................16

4. DATA REDUCTION .............................................................................................................................16

4.1 PRESSURE CALCULATION ....................................................................................................................16 4.2 TEMPERATURE CORRECTION...............................................................................................................17 4.3 BAROMETRIC CORRECTION (REQUIRED ONLY ON UN-VENTED TRANSDUCERS)....................................18

4.3.1 Vented Piezometers .....................................................................................................................19 4.4 ENVIRONMENTAL FACTORS.................................................................................................................19

5. TROUBLESHOOTING.........................................................................................................................19

APPENDIX A - SPECIFICATIONS .........................................................................................................21

APPENDIX B – STANDARD TEMPERATURE THERMISTOR TEMPERATURE DERIVATION.......................................................................................................................................................................22

APPENDIX C - NOTES REGARDING THE MODEL 4500C...............................................................24

APPENDIX D - NON LINEARITY AND THE USE OF A SECOND ORDER POLYNOMIAL TO IMPROVE THE ACCURACY OF THE CALCULATED PRESSURE................................................25

APPENDIX E - QUICK INSTRUCTIONS FOR INSTALLING A VIBRATING WIRE PIEZOMETER............................................................................................................................................27

APPENDIX F - MODEL 4500AR PIEZOMETER............................................................................28

LIST of FIGURES, TABLES and EQUATIONS

FIGURE 1-1 VIBRATING WIRE PIEZOMETER.................................................................................................... 1 FIGURE 2-1 SAMPLE CALIBRATION SHEET ..................................................................................................... 3 FIGURE 2-2 TYPICAL LEVEL MONITORING INSTALLATIONS ........................................................................... 6 FIGURE 2-3 TYPICAL BOREHOLE INSTALLATIONS .......................................................................................... 7 TABLE 1 SHOWING CEMENT/BENTONITE/WATER RATIOS FOR TWO GROUT MIXES. .......................................... 8 FIGURE 2-4 TYPICAL DAM INSTALLATIONS.................................................................................................... 9 FIGURE 2-5 TYPICAL SOFT SOILS INSTALLATION ......................................................................................... 10 FIGURE 2-6 TYPICAL MULTI-PIEZOMETER INSTALLATION ........................................................................... 13 FIGURE 2-7 RECOMMENDED LIGHTNING PROTECTION SCHEME ................................................................... 14 EQUATION 4-1 DIGITS CALCULATION........................................................................................................... 16 EQUATION 4-2 CONVERT DIGITS TO PRESSURE ............................................................................................ 16 TABLE 4-1 ENGINEERING UNITS MULTIPLICATION FACTORS ....................................................................... 17 EQUATION 4-3 TEMPERATURE CORRECTION ................................................................................................ 17 EQUATION 4-4 BAROMETRIC CORRECTION ................................................................................................... 18 EQUATION 4-5 CORRECTED PRESSURE CALCULATION .................................................................................. 18 TABLE A-1 VIBRATING WIRE PIEZOMETER SPECIFICATIONS........................................................................ 21 TABLE B-1 STANDARD TEMPERATURE THERMISTOR RESISTANCE VERSUS TEMPERATURE............. 22 TABLE B2 HIGH TEMPERATURE. TEMPERATURE V THERMISTOR RESISTANCE.............................................. 23

1. THEORY OF OPERATION Geokon Model 4500 Vibrating Wire Piezometers are intended primarily for long-term measurements of fluid and/or pore pressures in standpipes, boreholes, embankments, pipelines and pressure vessels. Several models of the 4500 series are available (see Appendix A). Contact Geokon sales engineers for specific application information. The instrument utilizes a sensitive stainless steel diaphragm to which a vibrating wire element is connected. See Figure 1-1. In use, changing pressures on the diaphragm cause it to deflect, and this deflection is measured as a change in tension and frequency of vibration of the vibrating wire element. The square of the vibration frequency is directly proportional to the pressure applied to the diaphragm. Two coils, one with a magnet, another with a pole piece, are located close to the wire. In use, a pulse of varying frequency (swept frequency) is applied to the coils and this causes the wire to vibrate primarily at its resonant frequency. When excitation ends the wire continues to vibrate and a sinusoidal AC electrical signal, at the resonant frequency, is induced in the coils and transmitted to the readout box where it is conditioned and displayed.

Filter

Filter Housing

O-rings

O-rings

Pressure Sensitive DiaphragmPluck and Read Coils

Magnet

Pole Piece

Hermetically sealed and evacuated space (unvented)

Piezometer Body

Wire Grip

Wire Grip

Thermistor

Coil Wire

Coil Wire

Thermistor Wires

Internal Bulkhead Seal

Vibrating Wire

Cable

Plasma Surge Arrestor

Ground Connection

Piezometer Housing

O-ring

O-ring

Figure 1-1 Vibrating Wire Piezometer To prevent damage to the sensitive diaphragm a filter is used to keep out solid particles. Figure 1-1 illustrates. Standard filters are 50 micron stainless steel; high air entry value tips are available on request. All exposed components are made of corrosion resistant stainless steel and, if proper installation techniques are used, the device should have an unlimited life. In salt water it may be necessary to use special materials for the diaphragm and housing. Portable readout units are available to provide the excitation, signal conditioning and readout of the instrument. Datalogging systems are also available for remote unattended data collection of multiple sensors. Contact Geokon for additional information. Calibration data are supplied with each piezometer for conversion of gage readings to engineering units such as pressure or level. See Section 4.

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2. INSTALLATION (For Quick Installation Instructions see AppendixE)

2.1 Preliminary Tests Upon receipt of the piezometer the zero reading should be checked and noted (see Sections 3.1 to 3.3 for readout instructions). A thermistor is included inside the body of the piezometer (Figure 1-1) for the measurement of temperature (see Section 3.4 for instructions).

Calibration data are supplied with each gage and a zero reading, at a specific temperature and barometric pressure, is included. Zero readings at the site should coincide with the calibration zero readings within +/- 50 digits after barometric and temperature corrections are made. The factory elevation is +580 ft. Before March 21, 1995 factory barometric pressure readings were corrected to sea level; readings after this date represent absolute pressure. (Barometric pressure changes with elevation at a rate of ½ psi per 1,000 ft.) See Figure 2-1 for a sample calibration sheet.

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Figure 2-1 Sample Calibration Sheet

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2.1.1 Establishing an Initial Zero Reading

Vibrating Wire Piezometers differ from other types of pressure sensors in that they

indicate a reading at zero pressure. Therefore it is imperative that an accurate initial zero pressure reading be obtained for each piezometer as this reading will be used in all subsequent data reduction.

There are different ways of doing this but the essential element in all methods is that the piezometer be allowed to thermally stabilize in a constant temperature environment while the pressure on the piezometer is barometric only. Because of the way the piezometer is constructed it takes about 5 to 15 minutes for the temperature of all the different elements to equalize.

It will be necessary to measure the barometric pressure only if the piezometer is un-vented and if it will be installed in a location that is subject to barometric pressure changes that require correction, such as in an open well. A piezometer sealed in place at depth could be recording pressures in groundwater that is not hydraulically connected to the atmosphere, and, for which, barometric pressure compensation would be inappropriate.

The recommended way to achieve temperature stability is to hang the piezometer in the borehole at a point just above the water and wait until the piezometer reading has stopped changing. Now take the zero reading and read the temperature, indicated by the thermistor inside the piezometer.

Another way is to place the piezometer under water in a bucket and allow 5 to 15 minutes for the temperature to stabilize, then lift the piezometer out of the water and immediately take a reading. When doing this, lift the piezometer by the cable only, do not handle the piezometer housing as body heat from the hand could cause temperature transients. Use the thermistor inside the piezometer to measure the water temperature.

Another way is to simply read the piezometer while in the air while making sure that the temperature has had time to stabilized. If this method is chosen be sure that the piezometer is protected from sunlight or sudden changes of temperature: Wrapping it in some insulating material is recommended.

Yet another way is to lower the piezometer to a known depth as marked out on the piezometer cable, (The diaphragm inside the piezometer is located approximately ¾ inch (15mm), from the tip. Then use a dip meter to accurately measure the depth to the water surface. Now, after temperature stabilization, read the piezometer pressure and, using the factory calibration constants and a knowledge of the pressure (height x density) of the water column above the piezometer, calculate either the equivalent zero pressure reading, if the linear regression is used, or the factor, C, if the second order polynomial is used.

A question may arise as to what to do with the filter stone while taking zero readings.

If a standard stainless steel filter is being used, it will not matter if the filter stone is saturated or not. But if ceramic high air entry filter stone is in use then it must be saturated while taking the zero readings and must not be allowed to dry out to the extent that surface tension effects can affect the zero reading. Caution. – do not allow the piezometer to freeze once it has been filled with water.

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2.1.2 Checking the Calibration The following procedure is recommended to verify the calibration factor as supplied on the calibration sheet (Figure 2-1). It should be borne in mind that the piezometer measures water pressure and that the conversion to a water level requires an accurate knowledge of the density of the water. 1. The best method is to remove the filter housing and filter stone from off the tip of

the piezometer: Pulling on the knurled ring will accomplish this. Alternatively, saturate the filter stone and fill the space between it and the diaphragm with water (Section 2.6).

2. Lower the piezometer to a point near the bottom of a water-filled borehole, or below

the surface of a body of water. The use of a dip meter to measure the actual depth of the water in the borehole will be very desirable.

3. Allow 15-20 minutes for the piezometer to come to thermal equilibrium. Using a

readout box record the reading at that level. 4. Raise the piezometer by known depth increments. Record the pressure reading at

each depth increment. Calculate the in-situ calibration factor and compare to the calibration factor on the calibration sheet. The two values should agree within 0.5%. Repeat test if necessary.

There are a couple of things that can affect the in-situ calibration:

The density of the in-situ water may not be 1gm/cc if it is saline or turbid. If this is the case then the factory calibration factor, should be adjusted to take into account the actual water density.

The water level inside the borehole may vary during the test due to the displacement of the water level as the cable is raised and lowered in the borehole. This effect will be greater where the borehole diameter is smaller. For example, a Model 4500S-50 piezometer lowered 50 feet below the water column in a 1 inch (.875 inch ID) standpipe will displace the water level by more than 4 feet! If a dip-meter is available it should be used to confirm the water levels at each depth increment.

2.2 Installation in Standpipes or Wells

A zero reading is first established (follow the procedures outlined in Section 2.1.1). The filter stone is saturated (follow the procedures in Section 2.6). Make a mark on the cable which will lie opposite the top of the standpipe, (well), when the piezometer has reached the desired depth. (The piezo diaphragm lies ¾ inch above the tip of the piezo).

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Zero Reading

Well CapPortable Readout

PiezometerWater Level

Piezometer Cable

Ground Surface

Typical Installation

Well CapPortable Readout

Piezometer

Water Level

Piezometer Cable

Ground Surface

Casing Bottom

Expected Change in Level

Casing Bottom

Figure 2-2 Typical Level Monitoring Installations Be sure the cable is securely fastened at the top of the well or readings could be in error due to slippage of the piezometer into the well. It is not recommended that piezometers be installed in wells or standpipes where an electrical pump and/or cable is present or nearby. Electrical interference from these sources can cause unstable readings. If unavoidable, it is recommended that the piezometer be placed inside a piece of steel pipe. In situations where packers are used in standpipes the same sequence as above should be noted and special care should be taken to avoid cutting the cable jacket with the packer since this could introduce a possible pressure leakage path.

2.3 Installation in Boreholes Geokon piezometers can be installed in boreholes in either single or multiple installations per hole, in cased or uncased holes. See Figure 2-3. Careful attention must be paid to borehole sealing techniques if pore pressures in a particular zone are to be monitored. Boreholes should be drilled either without drilling mud or with a material that degrades rapidly with time, such as Revert. The hole should extend from 6 inches to 12 inches below the proposed piezometer location and should be washed clean of drill cuttings. The bottom of the borehole should then be backfilled with clean fine sand to a point 6 inches below the piezometer tip. The piezometer can then be lowered, as delivered, into position. Preferably, the piezometer may be encapsulated in a canvas-cloth bag

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containing clean, saturated sand and then lowered into position. While holding the instrument in position (a mark on the cable is helpful) clean sand should be placed around the piezometer and to a point 6 inches above it. Figure 2-3 details two methods of isolating the zone to be monitored. Installation A Immediately above the "collection zone" the borehole should be sealed with either alternating layers of bentonite and sand backfill tamped in place for approximately 1 foot followed by common backfill or by an impermeable bentonite-cement grout mix. If multiple piezometers are to be used in a single hole the bentonite-sand plugs should be tamped in place below and above the upper piezometers and also at intervals between the piezometer zones. When designing and using tamping tools special care should be taken to ensure that the piezometer cable jackets are not cut during installation. Installation B Immediately above the "collection zone" the borehole should be filled with an impermeable bentonite grout.

Installation A

Piezometer

Bentonite Cement Grout

Filter Sand

Piezometer CablePortable Readout

Ground Surface

Installation B

Piezometer

Bentonite Grout

Filter Sand

Piezometer CablePortable Readout

Ground Surface

Bentonite

BentoniteSand

Collection Zone Collection Zone

Figure 2-3 Typical Borehole Installations Installation C It should be noted that since the vibrating wire piezometer is basically a no-flow instrument, collection zones of appreciable size are not required and the piezometer can, in fact, be placed directly in contact with most materials provided that the fines are not able to migrate through the filter. The latest thinking, (Mikkelson and Green, Piezometers in Fully Grouted Boreholes.Proceedings of FMGM 2003, Field Measurements in Geomechanics, Oslo, Norway, Sept. 2003. Contact Geokon for a copy o f this paper)

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is that it is not necessary to provide sand zones and that the piezometer can be grouted directly into the borehole using a bentonite cement grout only. The general rule for installing piezometers in this way is to use a bentonite grout that mimics the strength of the surrounding soil. The emphasis should be on controlling the water-cement ratio. This is accomplished by mixing the cement with the water first. The most effective way of mixing is in a 50 to 200 gallon barrel or tub using the drill-rig pump to circulate the mix. Any kind of bentonite powder used to make drilling mud, combined with Type 1 or 2 Portland cement can be used. The exact amount of bentonite added will vary somewhat. The table below shows 2 possible mixes for strengths of 50 psi and 4 psi. Add the measured amount of clean water to the barrel then gradually add the cement in the correct weight ratio. Next add the bentonite powder, slowly, so clumps do not form. Keep adding bentonite until the watery mix turns to an oily/slimy consistency. Let the grout thicken for another five to ten minutes. Add more bentonite as required until it is a smooth thick cream like pancake batter. It is now as heavy as it is feasible to pump. When pumping grout, unless the tremie-pipe is to be left in place, withdraw the tremie-pipe after each batch, by an amount corresponding to the grout level in the borehole. Caution: if the grout is pumped into the hole, rather than tremied, there is a danger that the piezometer will be over-ranged and damaged., So pumping direct into the bottom of the borehole should be avoided. It is good practice to read the piezometer while pumping.

Application Grout for Medium to Hard Soils

Grout for Soft Soils

Materials Weight Ratio by Weight Weight Ratio by Weight

Water 30 gallons 2.5 75 gallons 6.6

Portland Cement

94 lbs (1 sack)

1 94 lbs (1 sack)

1

Bentonite 25 lbs (as required)

0.3 39 lbs (as required)

0.4

Notes The 28 day compressive strength of this

mix is about 50 psi, similar to very stiff to hard clay. The modulus is about 10,000 psi

The 28 day strength of this mix is about 4psi,

similar to very soft clay.

Table 1 showing Cement/bentonite/water ratios for two grout mixes.

(For more details on this method of installation ask for a copy of the FMGM paper)

2.4 Installation in Fills and Embankments Geokon piezometers are normally supplied with direct burial cable suitable for placement in fills such as highway embankments and dams, both in the core and in the surrounding materials. In installations in non-cohesive fill materials the piezometer may be placed directly in the fill or, if large aggregate sizes are present, in a saturated sand pocket in the fill. If installed in large aggregate, additional measures may be necessary to protect the cable from damage.

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In fills such as impervious dam cores where sub-atmospheric pore water pressure may need to be measured (as opposed to the pore air pressure) a ceramic tip with a high air entry value is often used which should be carefully placed in direct contact with the compacted fill material (see Installation A of Figure 2-4). In partially saturated fills if only the pore air pressure is to be measured, the standard tip is satisfactory. It should be noted that the coarse tip measures the air pressure when there is a difference between the pore air pressure and the pore water pressure, and that the difference between the two pressures is due to the capillary suction in the soil. The general consensus is that the difference is normally of no consequence to embankment stability. As a general rule the coarse (low air entry) tip is suitable for most routine measurements and, in fine cohesive soils, sand pockets should not be used around the piezometer tip (see Installation B of Figure 2-4). In high traffic areas and in material which exhibit pronounced "weaving", a heavy-duty armored cable should be used. Cables are normally installed inside shallow trenches with the fill material consisting of smaller size aggregate. This fill is carefully hand compacted around the cable. Bentonite plugs are placed at regular intervals to prevent migration of water along the cable path.

Installation A

Fill Layer

Fill Layer

Fill Layer

Heavy Duty Piezometer

Filter in direct contact with fill(high air entry)

Heavy Duty Cable(in trench)

Pocket excavated in compacted fill

Fill material compacted by hand

Installation B

Fill Layer

Fill Layer

Fill Layer

Heavy Duty Piezometer

Filter in direct contact with sand(low air entry)

Heavy Duty Cable(in trench)

Pocket excavated in compacted fill

Sand compacted by hand

Figure 2-4 Typical Dam Installations

2.5 Installation by Pushing or Driving into Soft Soils The Model 4500DP piezometer is designed for pushing into soft soils. See Figure 2-5. The unit is connected directly to the drill rod (AW, EW or other) and pressed into the ground either by hand or by means of the hydraulics on the rig. The units can also be driven but the possibility of a zero shift due to the driving forces exists. The piezometer should be connected to the readout box and monitored during the driving process. If measurement pressures reach or exceed the calibrated range, the driving should be stopped and the pressures allowed to dissipate before continuing.

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Drill Rod(AW, EW or other)

Soft Soils

Piezometer

Piezometer pushed through soft soils to final location

Reaction Wings(if required)

Piezometer Cable

Casing Advanced Borehole

5' above final location

Left/Right Adaptor

EW Rod Adaptor

EW Rod

Augered or

Filter Housing

Figure 2-5 Typical Soft Soils Installation

The drill rod can be left in place or it can be removed. If it is to be removed then a special 5 foot section of EW (or AW) rod with wings and a left hand thread are attached directly to the piezometer tip. This section is detached from the rest of the drill string by rotating the string clockwise. The left hand thread will then loosen. The wings prevent the special EW rod from turning. A special LH/RH adapter is available from Geokon. The adapter is retrieved along with the drill string.

2.6 De-airing Filter Tips Caution. – do not allow the piezometer to freeze once it has been filled with water. Most Geokon filter tips can be removed for saturating and re-assembly. The procedures are as follows:

2.6.1 Low Air Entry Filter, Model 4500S and 4500PN For accurate results, total saturation of the filter is necessary. For the low air entry filter normally supplied, this saturation occurs as the tip is lowered into the water. Water is forced into the filter, compressing the air in the space between the filter stone and the pressure sensitive diaphragm. After a period of time, this air will dissolve into the water until the space and the filter is entirely filled with water. To speed up the saturation process, remove the filter assembly and fill the space above the diaphragm with water, then slowly replace the filter housing allowing the water to squeeze through the filter stone. With low pressure range piezometers (<10 psi) take readings with a readout box while pushing the filter housing on so as not to over-range the sensor.

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To maintain saturation, the unit should be kept under water until installation. If the 4500S piezometer is to be used in standpipes and raised and lowered many times the filter may loosen. A permanent filter assembly may be required. The removable filter may be fixed permanently by prick punching the piezometer tube approximately 1/16" to 1/8" behind the filter assembly joint. Screens are also available for standpipe installations. Screens are less likely than standard filters to become clogged where salts in the water can be deposited if the filter is allowed to dry out completely.

2.6.2 Removable Ceramic Filter, Model 4500S The ceramic filter on the 4500S piezometer is also removable for de-airing. Because of the high air entry characteristics, de-airing is particularly important for this filter assembly. Filters with different air entry values require different procedures. 1 Bar Filters

1. Remove the filter from the piezometer by carefully twisting and pulling on the filter housing assembly.

2. Boil the filter assembly in de-aired water. 3. Re-assemble the filter housing and piezometer under the surface of a container of

de-aired water. Be sure that no air is trapped in the transducer cavity. While pushing the filter on use a readout box to monitor the diaphragm pressure. Allow over-range pressure to dissipate before pushing further.

4. To maintain saturation, the unit should remain immersed until installation.

2 Bar and Higher The proper procedure for de-airing and saturating these filters is somewhat complex and should be done either at the factory by Geokon or by carefully following the instructions below:

1. Place the assembled piezometer, filter down, in a vacuum chamber with an inlet port at the bottom for de-aired water.

2. Close off the water inlet and evacuate the chamber. The transducer should be

monitored while the chamber is being evacuated. 3. When the maximum vacuum has been achieved, allow de-aired water to enter the

chamber and reach an elevation a few inches above the piezometer filter. 4. Close off the inlet port. Release the vacuum.

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5. Observe the transducer output. It will take as long as 24 hours for the filter to completely saturate (5 bar) and the pressure to rise to zero.

6. After saturation the transducer should be kept in a container of de-aired water

until installation. If de-aired at the factory a special cap is applied to the piezometer to maintain saturation.

2.6.3 Model 4500DP

The 4500 Drive Point is de-aired in the same way as the above models by first unscrewing the point of the piezometer assembly and then following the instruction for the 4500S.

2.7 Model 4500H Transducer When connecting the Model 4500H transducer to external fittings, the fitting should be tightened into the ¼"-NPT thread with a wrench on the flats provided on the transducer housing. Also, avoid tightening onto a closed system since the process of tightening the fittings could over-range and permanently damage the transducer. If in doubt, attach the gage leads to the readout box and take readings while tightening. Teflon tape on the threads makes for easier and more positive connection to the transducer. CAUTION: All high pressure sensors are potentially dangerous and care must be taken not to over-range them beyond their calibrated range. Sensors are tested to 150% of the range to provide a factor of safety.

2.8 Splicing and Junction Boxes Because the vibrating wire output signal is a frequency rather than current or voltage, variations in cable resistance have little effect on gage readings and, therefore, splicing of cables has no effect either and, in some cases, may be beneficial. For example, if multiple piezometers are installed in a borehole, and the distance from the borehole to the terminal box or datalogger is great, a splice (or junction box, see Figure 2-6) could be made to connect the individual cables to a single multi-conductor cable. This multi-conductor cable would then be run to the readout station. For such installations it is recommended that the piezometer be supplied with enough cable to reach the installation depth plus extra cable to pass through drilling equipment (rods, casing, etc.). The cable used for making splices should be a high quality twisted pair type with 100% shielding (with integral shield drain wire). When splicing, it is very important that the shield drain wires be spliced together! Splice kits recommended by Geokon incorporate casts placed around the splice then filled with epoxy to waterproof the connections. When properly made, this type of splice is equal or superior to the cable itself in strength and electrical properties. Contact Geokon for splicing materials and additional cable splicing instructions

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AC Adaptor

RF Antenna

AC Power

Grounding Stakes

Ground Connections

Portable Readout

Portable Computer

Multiconductor CablePiezometer Cables

Datalogger (with internal battery)

Junction Box or Splice

RS-232 Connection

Terminal/Multiplexer BoxManual Switch

Datalogger/Multiplexer Interconnect Cable

Phone Line

Piezometers

Solar PanelEquipment Shed

GroundConnection

Figure 2-6 Typical Multi-Piezometer Installation

. Junction boxes and terminal boxes are available from Geokon for all types of applications. In addition, portable readout equipment and datalogging hardware are available. See Figure 2-6. Contact Geokon for specific application information.

2.9 Lightning Protection In exposed locations it is vital that the piezometer be protected against lightning strikes. A tripolar plasma surge arrestor (Figure 1-1) is built into the body of the piezometer and protects against voltage spikes across the input leads. Following are additional lightning protection measures available; 1. If the instruments will be read manually with a portable readout (no terminal box) a

simple way to help protect against lightning damage is to connect the cable leads to a good earth ground when not in use. This will help shunt transients induced in the cable to ground thereby protecting the instrument.

2. Terminal boxes available from Geokon can be ordered with lightning protection built

in. There are two levels of protection;

The terminal board used to make the gage connections has provision for installation of plasma surge arrestors (similar to the device inside the piezometer).

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Lightning Arrestor Boards (LAB-3) can be incorporated into the terminal box. These units utilize surge arrestors and transzorbs to further protect the piezometer.

In the above cases the terminal box would be connected to an earth ground. 3. Improved protection using the LAB-3 can be had by placing the board in line with the

cable as close as possible to the installed piezometer (see Figure 2-7). This is the recommended method of lightning protection.

Piezometer

Piezometer Cable

To Terminal Box/Readout Equipment

Lightning Arrestor Board (LAB-3)(in special enclosure

Ground Stake

Ground Connection

accessible from surface)

Figure 2-7 Recommended Lightning Protection Scheme

3. TAKING READINGS

3.1 Operation of the GK-401 Readout Box The GK-401 is a basic readout for all vibrating wire gages. Connect the Readout using the flying leads or in the case of a terminal station, with a connector. The red and black clips are for the vibrating wire gage, the green lead for the shield drain wire. The GK-401 cannot read the thermistor (see Section 3.4). 1. Turn the display selector to position "B" (or "F"). Readout is in digits (Equation 4-1). 2. Turn the unit on and a reading will appear in the front display window. The last digit

may change one or two digits while reading. Record the value displayed. If zeros are displayed or the reading is unstable see section 5 for troubleshooting suggestions.

3. The unit will automatically turn itself off after approximately 4 minutes to conserve

power.

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3.2 Operation of the GK-403 Readout Box The GK-403 can store gage readings and also apply calibration factors to convert readings to engineering units. Consult the GK-403 Instruction Manual for additional information on Mode "G" of the Readout. The following instructions will explain taking gage measurements using Modes "B" and "F" (similar to the GK-401 switch positions "B" and "F"). Connect the Readout using the flying leads or in the case of a terminal station, with a connector. The red and black clips are for the vibrating wire gage, the white and green leads are for the thermistor and the blue for the shield drain wire. 1. Turn the display selector to position "B" (or "F"). Readout is in digits (Equation 4-1). 2. Turn the unit on and a reading will appear in the front display window. The last digit

may change one or two digits while reading. Press the "Store" button to record the value displayed. If the no reading displays or the reading is unstable see section 5 for troubleshooting suggestions. The thermistor will be read and output directly in degrees centigrade.

3. The unit will automatically turn itself off after approximately 2 minutes to conserve

power.

3.3 Operation of the GK404 Readout Box The GK404 is a palm sized readout box which displays the Vibrating wire value and the temperature in degrees centigrade. The GK-404 Vibrating Wire Readout arrives with a patch cord for connecting to the vibrating wire gages. One end will consist of a 5-pin plug for connecting to the respective socket on the bottom of the GK-404 enclosure. The other end will consist of 5 leads terminated with alligator clips. Note the colors of the alligator clips are red, black, green, white and blue. The colors represent the positive vibrating wire gage lead (red), negative vibrating wire gage lead (black), positive thermistor lead (green), negative thermistor lead (white) and transducer cable drain wire (blue). The clips should be connected to their respectively colored leads from the vibrating wire gage cable. Use the POS (Position) button to select position B and the MODE button to select Dg (digits). Other functions can be selected as described in the GK404 Manual. The GK-404 will continue to take measurements and display the readings until the OFF button is pushed, or if enabled, when the automatic Power-Off timer shuts the GK-404 off. The GK-404 continuously monitors the status of the (2) 1.5V AA cells, and when their combined voltage drops to 2V, the message Batteries Low is displayed on the screen. A fresh set of 1.5V AA batteries should be installed at this point

16

3.4 Measuring Temperatures Each vibrating wire piezometer is equipped with a thermistor for reading temperature. The thermistor gives a varying resistance output as the temperature changes. Usually the white and green leads are connected to the internal thermistor. High temperature versions use a different thermistor than the standard versions. The GK-403 and GK 404 readout boxes when used with the standard temperature thermistor will display the temperature in C automatically. They will not do this with high temperature thermistors. The GK 401 readout box will not read temperatures directly, instead an ohmmeter must be used. 1. Connect the ohmmeter to the two thermistor leads coming from the piezometer.

(Since the resistance changes with temperature are so large, the effect of cable resistance is usually insignificant. For long cables a correction can be applied – equal to 16 ohms per thousand feet.)

2. For standard temperature models, look up the temperature for the measured

resistance in Table B-1.Page 21 Alternately the temperature could be calculated using Equation B-1. For high temperature models use Table B2 or the equation B2 given on page 22.

4. DATA REDUCTION

4.1 Pressure Calculation The digits displayed by the Geokon Models GK-403 or GK-404 Readout Boxes on channel B are based on the equation

DigitsPeriod

231

10 or DigitsHz

2

1000

Equation 4-1 Digits Calculation For example, a piezometer reading 8000 digits corresponds to a period of 354s and a frequency of 2828 Hz. Note that in the above equation, the period is in seconds: the readout boxes display microseconds. Since digits are directly proportional to the applied pressure,

Pressure (Initial Reading - Current Reading) Calibration Factor or

P = (R0 - R1)G

Equation 4-2 Convert Digits to Pressure

Since the linearity of most sensors is within 0.2% FS the errors associated with non-linearity are of minor consequence. However, for those situations requiring the highest accuracy it may be desirable to use a second order polynomial to get a better fit of the data points. The use of a second order polynomial is explained in Appendix D. The calibration sheet, a typical example of which is shown in figure 2.1 on page 4, shows the data from which the linear gage factor and the second order polynomial coefficients are derived. Columns on the right show the size of the error incurred by assuming a linear

17

coefficient and the improvement which can be expected by going to a second order polynomial . In many cases the difference is minor. The calibration sheets gives the pressure in certain engineering units. These can be converted to other engineering units using the multiplication factors shown in Table 4-1 below.

From To

psi

"H2O

'H2O

mm H20

m H20

"HG

mm HG

atm

mbar

bar

kPa

MPa

psi 1 .036127 .43275 .0014223 1.4223 .49116 .019337 14.696 .014503 14.5039 .14503 145.03 "H2O 27.730 1 12 .039372 39.372 13.596 .53525 406.78 .40147 401.47 4.0147 4016.1

'H2O 2.3108 .08333 1 .003281 3.281 1.133 .044604 33.8983 .033456 33.4558 .3346 334.6

mm H20 704.32 25.399 304.788 1 1000 345.32 13.595 10332 10.197 10197 101.97 101970

m H20 .70432 .025399 .304788 .001 1 .34532 .013595 10.332 .010197 10.197 .10197 101.97

"HG 2.036 .073552 .882624 .0028959 2.8959 1 .03937 29.920 .029529 29.529 .2953 295.3 mm HG 51.706 1.8683 22.4196 .073558 73.558 25.4 1 760 .75008 750.08 7.5008 7500.8

atm .06805 .0024583 .0294996 .0000968 .0968 .03342 .0013158 1 .0009869 .98692 .009869 9.869 mbar 68.947 2.4908 29.8896 .098068 98.068 33.863 1.3332 1013.2 1 1000 10 10000 bar .068947 .0024908 .0298896 .0000981 .098068 .033863 .001333 1.0132 .001 1 .01 10 kPa 6.8947 .24908 2.98896 .0098068 9.8068 3.3863 .13332 101.320 .1 100 1 1000 MPa .006895 .000249 .002988 .00000981 .009807 .003386 .000133 .101320 .0001 .1 .001 1

Table 4-1 Engineering Units Multiplication Factors

Note: Due to changes in specific gravity with temperature the factors for mercury and water in the above table are approximations!

4.2 Temperature Correction Careful selection of materials is made in constructing the vibrating wire piezometer to minimize thermal effects, however, most units still have a slight temperature coefficient. Consult the supplied calibration sheet to obtain the coefficient for a given piezometer. Since piezometers are normally installed in a tranquil and constant temperature environment, corrections are not normally required. If however, that is not the case for a selected installation, corrections can be made using the internal thermistor (Figure 1-1) for temperature measurement. See Section 3.4 for instructions regarding obtaining the piezometer temperature. Temperature correction equation is as follows;

Temperature Correction (Current Temperature - Initial Temperature) Thermal Factor

or PT = (T1-T0) x K

Equation 4-3 Temperature Correction

The calculated correction would then be added to the Pressure calculated using Equation 4-2. If the engineering units were converted remember to apply the same conversion to the calculated temperature correction! For example, assume the initial temperature was 22 C, the current temperature is 15 C, and the thermal coefficient is 0.004326 PSI per C rise (Figure 2-1). The temperature correction is +0.03 PSI.

18

4.3 Barometric Correction (required only on un-vented transducers) Since the standard piezometer is hermetically sealed and un-vented, it responds to changes in atmospheric pressure. That being the case, corrections may be necessary, particularly for the sensitive, low pressure models. For example, a barometric pressure change from 29 to 31 inches of mercury would result in 1 PSI of error (or 2.3 feet if monitoring water level in a well!). Thus it is advisable to read and record the barometric pressure every time the piezometer is read. A separate pressure transducer (piezometer), kept out of the water, may be used for this purpose. Barometric correction equation is as follows;

Barometric Correction (Current Barometer - Initial Barometer) Conversion Factor

or PB = (S1-S0) x F

Equation 4-4 Barometric Correction

Since barometric pressure is usually recorded in inches of mercury a Conversion Factor is necessary to convert to PSI. The Conversion Factor for inches of mercury to PSI is .491. Table 4-1 lists other common Conversion Factors. The calculated correction is usually subtracted from the Pressure calculated using Equation 4-2. If the engineering units were converted remember to apply the same conversion to the calculated barometric correction! The user should be cautioned that this correction scheme assumes ideal conditions. In reality, conditions are not always ideal. For example, if the well is sealed, barometric effects at the piezometer level may be minimal or attenuated from the actual changes at the surface. Thus errors may result when applying a correction which is not required. We recommend, in these cases, to independently record barometric pressure changes and correlate these with observed pressure changes to arrive at a correction factor.

An alternative to making barometric correction is to use piezometers that are vented to the atmosphere as noted section 4.3.1. However, vented piezos only make sense if the piezo is in an open well or standpipe and the user is only interested in the water level. Otherwise, if the piezo is buried it is not certain that the full effect of the barometric change will be felt immediately at the piezo and is more likely to be attenuated and delayed, in which case a vented piezo would automatically apply a correction that is too large and too soon. Having an on-site barometer with un-vented piezos also has the advantage that you can see the barometric change and judge to what extent it may have affected the piezo reading.

Equation 4-5 describes the pressure calculation with temperature and barometric correction applied.

Pcorrected = ((R0 - R1)G) + ((T1-T0) x K) - ((S1-S0) x F)

Equation 4-5 Corrected Pressure Calculation

19

4.3.1 Vented Piezometers Vented piezometers are designed to eliminate barometric effects. The space inside the transducer is not hermetically sealed and evacuated (see Figure 1-1), but is connected via a tube (integral with the cable) to the atmosphere. A chamber containing desiccant capsules is attached to the end of the tube to prevent moisture from entered the transducer cavity. Vented piezometers require more maintenance then non-vented types, and there is always a danger that water can find its way into the inside of the transducer and ruin it. As supplied, the outer end of the desiccant chamber is closed by means of a seal screw to keep the desiccant fresh during storage and transportation. THE SEAL SCREW MUST BE REMOVED BEFORE THE PIEZOMETER IS PUT INTO SERVICE! The desiccant capsules are blue when fresh, they will gradually turn pink as they absorb moisture. When they have turned light pink in color they should be replaced. Contact Geokon for replacement capsules.

4.4 Environmental Factors Since the purpose of the piezometer installation is to monitor site conditions, factors which may affect these conditions should always be observed and recorded. Seemingly minor effects may have a real influence on the behavior of the structure being monitored and may give an early indication of potential problems. Some of the factors include, but are not limited to; blasting, rainfall, tidal levels, excavation and fill levels and sequences, traffic, temperature and barometric changes (and other weather conditions), changes in personnel, nearby construction activities, seasonal changes, etc.

5. TROUBLESHOOTING Maintenance and troubleshooting of vibrating wire piezometers is confined to periodic checks of cable connections and maintenance of terminals. The transducers themselves are sealed and not user serviceable. Following are typical problems and suggested remedial action. Piezometer fails to give a reading 1. Check the resistance of the coils by connecting an ohmmeter across the gage

terminals. Nominal resistance is 180 (5%), plus cable resistance at approximately 16 per 1000' of 22 AWG wire. If the resistance is very high or infinite the cable is probably broken or cut. If the resistance is very low the gage conductors may be shorted. If a cut or a short is located in the cable, splice according to instructions in Section 2.8.

2. Check the readout with another gage. 3. The Piezometer may have been over-ranged or shocked. Inspect the diaphragm and

housing for damage. Contact the factory. Piezometer reading unstable 1. Connect the shield drain wire to the readout using the green (GK-401) or the blue

(GK-403) clip. 2. Isolate the readout from the ground by placing it on a piece of wood or similar non-

conductive material.

20

3. Check for sources of nearby noise such as motors, generators, antennas or electrical cables. Move the piezometer cables if possible. Contact the factory for filtering and shielding equipment available.

4. The Piezometer may have been damaged by over-ranging or shock. 5. The body of the Piezometer may be shorted to the shield. Check the resistance

between the shield drain wire and the Piezometer housing. Thermistor resistance is too high 1. Likely there is an open circuit. Check all connections, terminals and plugs. If a cut is

located in the cable, splice according to instructions in Section 2.8. Thermistor resistance is too low 1. Likely there is a short. Check all connections, terminals and plugs. If a short is

located in the cable, splice according to instructions in Section 2.8. 2. Water may have penetrated the interior of the piezometer. There is no remedial

action.

21

APPENDIX A - SPECIFICATIONS

Model 4500S 4500AL1 4500AR 4500B 4500C 4500DP 45802 Available Ranges

(psi)

0-50 0-100 0-150 0-250 0-500 0-750

0-1000 0-1500 0-3000 0-5000 0-10000 0-15000

0-5 0-10 0-25

0-50 0-100 0-250

0-50 0-100 0-250

0-10 0-25 0-50 0-150 0-250 0-500 0-750

0-1000 0-1500 0-3000 0-5000 0-10000

0-1 0-5

Resolution 0.025% FS 0.025% FS 0.025% FS 0.025% FS 0.05% FS 0.025% FS 0.01% FSLinearity < 0.5% FS3 < 0.5% FS3 < 0.5% FS3 < 0.5% FS3 < 0.5% FS3 < 0.5% FS3 < 0.5% FS3

Accuracy 0.1% FS4 0.1% FS4 0.1% FS4 0.1% FS4 0.1% FS4 0.1% FS4 0.1% FS

Over-Range 2 FS 2 FS 2 FS 2 FS 2 FS 2 FS 2 FS Thermal

Coefficient <0.025%

FS/ °C

<0.05% FS/°C

<0.05% FS/°C

<0.025% FS/ °C

<0.05% FS/ °C

<0.025% FS/°C

<0.025% FS/ °C

Temperature Range

-20°C to +80°C

-20°C to +80°C

-20°C to +80°C

-20°C to +80°C

-20°C to +80°C

-20°C to +80°C

-20°C to +80°C

OD .75" 19.05 mm

1" 25.40 mm

.75" 19.05 mm

.687" 17.45 mm

.437" 11.10 mm

1.3” 33.3mm

1.5" 38.10 mm

Length 5.25" 133 mm

5.25" 133 mm

10” 254 mm

5.25" 133 mm

6.5" 165 mm

7.36” 187 mm

6.5" 165 mm

Table A-1 Vibrating Wire Piezometer Specifications

Accuracy of Geokon test apparatus: 0.1% Contact Geokon for specific application information. Notes: 1 Accuracy of test apparatus: 0.05% 2 Other ranges available upon request. 3 0.1% FS linearity available upon request. 4 Derived using 2nd order polynomial.

22

APPENDIX B – STANDARD TEMPERATURE THERMISTOR TEMPERATURE DERIVATION

Thermistor Type: YSI 44005, Dale #1C3001-B3, Alpha #13A3001-B3 Resistance to Temperature Equation B1:

TA B LnR C LnR

1

273 23( ) ( ).

Where; T Temperature in C. LnR Natural Log of Thermistor Resistance A 1.4051 10-3 (coefficients calculated over the 50 to +150 C. span) B 2.369 10-4 C 1.019 10-7

Ohms Temp Ohms Temp Ohms Temp Ohms Temp Ohms Temp 201.1K -50 16.60K -10 2417 30 525.4 70 153.2 110 187.3K -49 15.72K -9 2317 31 507.8 71 149.0 111 174.5K -48 14.90K -8 2221 32 490.9 72 145.0 112 162.7K -47 14.12K -7 2130 33 474.7 73 141.1 113 151.7K -46 13.39K -6 2042 34 459.0 74 137.2 114 141.6K -45 12.70K -5 1959 35 444.0 75 133.6 115 132.2K -44 12.05K -4 1880 36 429.5 76 130.0 116 123.5K -43 11.44K -3 1805 37 415.6 77 126.5 117 115.4K -42 10.86K -2 1733 38 402.2 78 123.2 118 107.9K -41 10.31K -1 1664 39 389.3 79 119.9 119 101.0K -40 9796 0 1598 40 376.9 80 116.8 120 94.48K -39 9310 1 1535 41 364.9 81 113.8 121 88.46K -38 8851 2 1475 42 353.4 82 110.8 122 82.87K -37 8417 3 1418 43 342.2 83 107.9 123 77.66K -36 8006 4 1363 44 331.5 84 105.2 124 72.81K -35 7618 5 1310 45 321.2 85 102.5 125 68.30K -34 7252 6 1260 46 311.3 86 99.9 126 64.09K -33 6905 7 1212 47 301.7 87 97.3 127 60.17K -32 6576 8 1167 48 292.4 88 94.9 128 56.51K -31 6265 9 1123 49 283.5 89 92.5 129 53.10K -30 5971 10 1081 50 274.9 90 90.2 130 49.91K -29 5692 11 1040 51 266.6 91 87.9 131 46.94K -28 5427 12 1002 52 258.6 92 85.7 132 44.16K -27 5177 13 965.0 53 250.9 93 83.6 133 41.56K -26 4939 14 929.6 54 243.4 94 81.6 134 39.13K -25 4714 15 895.8 55 236.2 95 79.6 135 36.86K -24 4500 16 863.3 56 229.3 96 77.6 136 34.73K -23 4297 17 832.2 57 222.6 97 75.8 137 32.74K -22 4105 18 802.3 58 216.1 98 73.9 138 30.87K -21 3922 19 773.7 59 209.8 99 72.2 139 29.13K -20 3748 20 746.3 60 203.8 100 70.4 140 27.49K -19 3583 21 719.9 61 197.9 101 68.8 141 25.95K -18 3426 22 694.7 62 192.2 102 67.1 142 24.51K -17 3277 23 670.4 63 186.8 103 65.5 143 23.16K -16 3135 24 647.1 64 181.5 104 64.0 144 21.89K -15 3000 25 624.7 65 176.4 105 62.5 145 20.70K -14 2872 26 603.3 66 171.4 106 61.1 146 19.58K -13 2750 27 582.6 67 166.7 107 59.6 147 18.52K -12 2633 28 562.8 68 162.0 108 58.3 148 17.53K -11 2523 29 543.7 69 157.6 109 56.8 149

55.6 150

Table B-1 STANDARD TEMPERATURE Thermistor Resistance versus

Temperature

23

High Temperature Thermistor Linearization using SteinHart-Hart Log Equation

Thermistor Type: Thermometrics BR55KA822J

Basic Equation B2: TA B LnR C LnR

1

273 23( ) ( )

.

Where: T Temperature in C. LnR Natural Log of Thermistor Resistance A 1.02569 10-3 B 2.478265 10-4 C 1.289498 10-7 Note: Coefficients calculated over -30 to +260 C. span.

Table B2

Temp R (ohms)

LnR LnR3 Calculated Temp

Diff FS Error Temp R (ohms)

LnR LnR3 CalculatedTemp

Diff FS Error

-30 113898 11.643 1578.342 -30.17 0.17 0.06 120 407.62 6.010 217.118 120.00 0.00 0.00

-25 86182 11.364 1467.637 -25.14 0.14 0.05 125 360.8 5.888 204.162 125.00 0.00 0.00

-20 65805 11.094 1365.581 -20.12 0.12 0.04 130 320.21 5.769 191.998 130.00 0.00 0.00

-15 50684.2 10.833 1271.425 -15.10 0.10 0.03 135 284.95 5.652 180.584 135.00 0.00 0.00

-10 39360 10.581 1184.457 -10.08 0.08 0.03 140 254.2 5.538 169.859 140.01 -0.01 0.00

-5 30807.4 10.336 1104.068 -5.07 0.07 0.02 145 227.3 5.426 159.773 145.02 -0.02 -0.01

0 24288.4 10.098 1029.614 -0.05 0.05 0.02 150 203.77 5.317 150.314 150.03 -0.03 -0.01

5 19294.6 9.868 960.798 4.96 0.04 0.01 155 183.11 5.210 141.428 155.04 -0.04 -0.01

10 15424.2 9.644 896.871 9.98 0.02 0.01 160 164.9 5.105 133.068 160.06 -0.06 -0.02

15 12423 9.427 837.843 14.98 0.02 0.01 165 148.83 5.003 125.210 165.08 -0.08 -0.03

20 10061.4 9.216 782.875 19.99 0.01 0.00 170 134.64 4.903 117.837 170.09 -0.09 -0.03

25 8200 9.012 731.893 25.00 0.00 0.00 175 122.1 4.805 110.927 175.08 -0.08 -0.03

30 6721.54 8.813 684.514 30.01 -0.01 0.00 180 110.95 4.709 104.426 180.07 -0.07 -0.02

35 5540.74 8.620 640.478 35.01 -0.01 0.00 185 100.94 4.615 98.261 185.10 -0.10 -0.04

40 4592 8.432 599.519 40.02 -0.02 -0.01 190 92.086 4.523 92.512 190.09 -0.09 -0.03

45 3825.3 8.249 561.392 45.02 -0.02 -0.01 195 84.214 4.433 87.136 195.05 -0.05 -0.02

50 3202.92 8.072 525.913 50.01 -0.01 -0.01 200 77.088 4.345 82.026 200.05 -0.05 -0.02

55 2693.7 7.899 492.790 55.02 -0.02 -0.01 205 70.717 4.259 77.237 205.02 -0.02 -0.01

60 2276.32 7.730 461.946 60.02 -0.02 -0.01 210 64.985 4.174 72.729 210.00 0.00 0.00

65 1931.92 7.566 433.157 65.02 -0.02 -0.01 215 59.819 4.091 68.484 214.97 0.03 0.01

70 1646.56 7.406 406.283 70.02 -0.02 -0.01 220 55.161 4.010 64.494 219.93 0.07 0.02

75 1409.58 7.251 381.243 75.01 -0.01 0.00 225 50.955 3.931 60.742 224.88 0.12 0.04

80 1211.14 7.099 357.808 80.00 0.00 0.00 230 47.142 3.853 57.207 229.82 0.18 0.06

85 1044.68 6.951 335.915 85.00 0.00 0.00 235 43.673 3.777 53.870 234.77 0.23 0.08

90 903.64 6.806 315.325 90.02 -0.02 -0.01 240 40.533 3.702 50.740 239.69 0.31 0.11

95 785.15 6.666 296.191 95.01 -0.01 0.00 245 37.671 3.629 47.788 244.62 0.38 0.13

100 684.37 6.528 278.253 100.00 0.00 0.00 250 35.055 3.557 45.001 249.54 0.46 0.16

105 598.44 6.394 261.447 105.00 0.00 0.00 255 32.677 3.487 42.387 254.44 0.56 0.19

110 524.96 6.263 245.705 110.00 0.00 0.00 260 30.496 3.418 39.917 259.34 0.66 0.23

115 461.91 6.135 230.952 115.00 0.00 0.00

Table B2 High Temperature. Temperature v Thermistor Resistance

24

APPENDIX C - NOTES REGARDING THE MODEL 4500C Installation The construction of this very slender vibrating wire transducer, requires a miniaturization of the internal parts and consequently they are somewhat delicate. Despite every precaution it is possible for the zero to shift during shipment due to rough handling. However, tests have shown that the zero may shift but the calibration factors do not change. Therefore it is doubly important that the initial no load zero reading be taken prior to installation. And it is also important to handle the transducer gently during the installation procedure. If the pressures to be measured are less than 5 psi the filter stone in the filter housing must be saturated. However, the filter stone and housing are not removable in the 4500C. Any attempt to remove the filter stone or the housing will destroy the transducer!

To Pump

Transducer

Water

Tubing

Transducer Cable

Filter Housing

To saturate the filter a hand vacuum pump and short length of tubing (½" surgical tubing) is required. Attach the tube to the transducer as shown in the figure. Fill the tubing with approximately 2" (5 cm) of water. Hold the transducer so that the water rests on the filter. Attach the other end of the tube to the hand vacuum pump. While holding the transducer so that the water rests on the filter (and doesn't enter the pump!), squeeze the hand pump to initiate vacuum in the tubing. This will draw the air out of the filter and the space behind it. The water will replace it. A vacuum of 20-25" Hg. (50-65 cm Hg.) is sufficient for proper evacuation. A hand pump that has been used successfully is the mityvacII® by Neward Enterprises, Inc. of Cucamonga, CA, USA. Hand pumps and tubing are available from the factory. Data Reduction Data reduction follows the same procedures as outlined in Section 4 of this manual.. Use Table 4-1 to convert psi to other engineering units.

25

APPENDIX D - NON LINEARITY AND THE USE OF A SECOND ORDER POLYNOMIAL TO IMPROVE THE ACCURACY OF THE CALCULATED PRESSURE

Most vibrating wire pressure transducers are sufficiently linear ( 0.2 % FS) that use of the linear calibration factor satisfies normal requirements. However, it should be noted that the accuracy of the calibration data, which is dictated by the accuracy of the calibration apparatus, is always 0.1 % FS. This level of accuracy can be recaptured, even where the transducer is non-linear, by the use of a second order polynomial expression which gives a better fit to the data then does a straight line.

The polynomial expression has the form:

pressure = AR 2 BR C where R is the reading (digits channel B) and A,B,C, are coefficients. The figure on page 24 shows a calibration sheet of a transducer which has a comparatively high non-linearity. The figure under the “Linearity (%FS)” column is

Calculated pressure- True pressure x 100% = G(R0 -R1 ) -P x 100% Full-scale Pressure F.S Note The linearity is calculated using the regression zero for R0 For example when P= 40 psi, G (R0 - R1 ) = 0.029021( 9145-7773), gives a calculated pressure of 39.817 psi. The error is 0.183 psi equal to 5 inches of water. Whereas the polynomial expression gives a calculated pressure of A (7773) 2 B (7773) C = 39.996 psi and the actual error is only 0.004 psi or 0.1 inch of water. Note. If the polynomial equation is used it is important that the value of C, in the polynomial equation, be taken in the field, following the procedures described in section 2.1.1. The field value of C is calculated by inserting the initial zero reading into the polynomial equation with the pressure, P, set to zero. It should be noted that where changes of water levels are being monitored it makes little difference whether the linear coefficient or the polynomial expression is used.

26

Vibrating Wire Pressure Transducer Calibration Sheet

27

APPENDIX E - QUICK INSTRUCTIONS FOR INSTALLING A VIBRATING WIRE PIEZOMETER.

Take a zero reading at zero, (atmospheric), pressure. Make sure that the temperature has not changed for 15 minutes previously. (Or until the piezo reading has stabilized). Check that this zero reading is compatible with the zero on the calibration sheet

Record the barometric pressure and the temperature at the time the zero reading

is taken.

Carefully measure the length of the cable and make a mark on the cable which will lie opposite the top of the borehole, well, or standpipe when the piezometer has reached the desired depth. (The piezo diaphragm lies ¾ inch above the tip of the piezo).

Saturate the piezometer filter. (Section 2.6)

Follow the instruction of Section 2.2 for installation in standpipes or wells or

Section 2.3 for boreholes.

28

APPENDIX F - Model 4500AR piezometer

The Model 4500 AR piezometer is designed to be used with readouts systems that can read frequency but do not have the capability to “pluck’ the VW gage. This sensor has built-in electronics that cause the gage wire to vibrate in a continuous mode at its resonant frequency. The output from the sensor is a 5 volt DC square wave at this frequency. A DC input voltage in the range of 6- 24 volts is required to operate the gage. The current consumption is approximately 21 mA at 12VDC. The gage output is independent of the input voltage. Multiple sensors powered simultaneously can be read at quite fast rates, up to 5 sensors per second and dynamic measurements on a single sensor can be made up to about 20Hz. The gage is installed in the field in the same way that the Model 4500 standard piezometer is installed. (See Section 2) Piezometer Wiring: The 3-pair cable is wired in pairs with each pair comprising one colored and one black lead. Red +6-24 VDC Power Red’s black Ground White Output White’s black Output Ground Green Thermistor + Green’s black Thermistor – Bare Shield Upon power up the gage will immediately start to “ring” at the resonant frequency and will continue to do so until the power is removed. Continuous operation will have no effect on the gage life. Note The sensor comprises two transducers, the VW pressure sensor and a thermistor for measuring temperature. The signals from the VW transducer are high level frequency and will interfere with the thermistor output if left powered during the period that the thermistor is being read. If the temperature reading is important the power to the pressure sensor should be switched off while the reading is taken.

Instruction Manual

Model 6300

Vibrating Wire In-Place Inclinometer

No part of this instruction manual may be reproduced, by any means, without the written consent of Geokon, Inc.

The information contained herein is believed to be accurate and reliable. However, Geokon, Inc. assumes no responsibility for errors, omissions or misinterpretation. The information herein is subject to change without

notification.

Copyright © 1995, 1996 1997, 2009, 2011 by Geokon, Inc. (Doc Rev P, 11/11)

Warranty Statement

Geokon, Inc. warrants its products to be free of defects in materials and workmanship, under normal

use and service for a period of 13 months from date of purchase. If the unit should malfunction, it must

be returned to the factory for evaluation, freight prepaid. Upon examination by Geokon, if the unit is

found to be defective, it will be repaired or replaced at no charge. However, the WARRANTY is VOID

if the unit shows evidence of having been tampered with or shows evidence of being damaged as a

result of excessive corrosion or current, heat, moisture or vibration, improper specification,

misapplication, misuse or other operating conditions outside of Geokon's control. Components which

wear or which are damaged by misuse are not warranted. This includes fuses and batteries.

Geokon manufactures scientific instruments whose misuse is potentially dangerous. The instruments

are intended to be installed and used only by qualified personnel. There are no warranties except as

stated herein. There are no other warranties, expressed or implied, including but not limited to the

implied warranties of merchantability and of fitness for a particular purpose. Geokon, Inc. is not

responsible for any damages or losses caused to other equipment, whether direct, indirect, incidental,

special or consequential which the purchaser may experience as a result of the installation or use of the

product. The buyer's sole remedy for any breach of this agreement by Geokon, Inc. or any breach of any

warranty by Geokon, Inc. shall not exceed the purchase price paid by the purchaser to Geokon, Inc. for

the unit or units, or equipment directly affected by such breach. Under no circumstances will Geokon

reimburse the claimant for loss incurred in removing and/or reinstalling equipment.

Every precaution for accuracy has been taken in the preparation of manuals and/or software, however,

Geokon, Inc. neither assumes responsibility for any omissions or errors that may appear nor assumes

liability for any damages or losses that result from the use of the products in accordance with the

information contained in the manual or software.

TABLE of CONTENTS

1. INTRODUCTION ..................................................................................................................................................1

1.1. TILT SENSOR CONSTRUCTION ..........................................................................................................................2 2.1. PRELIMINARY TESTS ........................................................................................................................................3 2.2. MODEL 6300 ASSEMBLY AND INSTALLATION ..................................................................................................3

2.2.1. Uniaxial System.........................................................................................................................................4 2.2.2. Biaxial System ...........................................................................................................................................5

2.3. FLUID DAMPING ...............................................................................................................................................7 2.4. SPLICING AND JUNCTION BOXES ......................................................................................................................7

3. TAKING READINGS............................................................................................................................................8

3.1. OPERATION OF THE GK-403 READOUT BOX ..................................................................................................8 3.2 OPERATION OF THE GK404 READOUT BOX .....................................................................................................8 3.3. MICRO-10 DATALOGGER................................................................................................................................9 3.4. MEASURING TEMPERATURE ............................................................................................................................9

4. DATA REDUCTION ...........................................................................................................................................10

4.1. INCLINATION CALCULATION ..........................................................................................................................10 4.2. TEMPERATURE CORRECTION .........................................................................................................................10 4.4. ENVIRONMENTAL FACTORS ...........................................................................................................................11

5. TROUBLESHOOTING.......................................................................................................................................13

APPENDIX A - SPECIFICATIONS ......................................................................................................................14

A.1. VIBRATING WIRE TILT SENSOR ....................................................................................................................14 A.2. THERMISTOR (SEE APPENDIX B ALSO) ..........................................................................................................14

APPENDIX B - THERMISTOR TEMPERATURE DERIVATION ...................................................................15

APPENDIX C - EXCITATION AND READOUT PARAMETERS ....................................................................16

MODEL 6300 WITH MICRO-10 DATALOGGER ......................................................................................................16 EXCITATION ...........................................................................................................................................................16 EXCITATION FREQUENCY......................................................................................................................................16 OFFSET ...................................................................................................................................................................16

APPENDIX D - ADDRESSABLE SYSTEMS ........................................................................................................17

USING THE 8031 DISTRIBUTED MULTIPLEXER ........................................................................................................17 CIRCUIT BOARD CONNECTOR PIN-OUTS:................................................................................................................18 CIRCUIT BOARD JUMPER SETTINGS: ......................................................................................................................19 CIRCUIT BOARD DIP SWITCH SETTINGS: ...............................................................................................................19 SW2 ADDRESS TABLE: (CHANNEL 1 DEFAULT) .......................................................................................................20

MODEL 8031 SPECIFICATIONS: ..........................................................................................................................23

LIST of FIGURES, TABLES and EQUATIONS

FIGURE 1 - MODEL 6300 TILT SENSOR ASSEMBLY........................................................................................................ 1 FIGURE 2 - MODEL 6300 TILT SENSOR .......................................................................................................................... 2 FIGURE 5 - BIAXIAL SENSOR ORIENTATION................................................................................................................... 5 EQUATION 1 CALCULATION OF TILT (LINEAR) .......................................................................................................... 10 EQUATION 2 CALCULATION OF TILT (POLYNOMIAL) ................................................................................................. 10 EQUATION 3 TEMPERATURE CORRECTION................................................................................................................. 10 EQUATION 4 – HORIZONTAL DISPLACEMENT CALCULATION ...................................................................................... 11 FIGURE 7 - SAMPLE MODEL 6300 CALIBRATION SHEET .............................................................................................. 12 TABLE A-1 MODEL 6300 TILT SENSOR SPECIFICATIONS............................................................................................. 14 EQUATION B-1 CONVERT THERMISTOR RESISTANCE TO TEMPERATURE.................................................................... 15 TABLE B-1 THERMISTOR RESISTANCE VERSUS TEMPERATURE .................................................................................. 15

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1. INTRODUCTION The Geokon Model 6300 Vibrating Wire In-Place Inclinometer system is designed for long-term monitoring of deformations in structures such as dams, embankments, foundation walls and the like. The basic principle is the utilization of tilt sensors to make accurate measurement of inclination, over segments, in boreholes drilled into the structure being studied. The continuous nature of the instrument allows for very precise measurement of changes in the borehole profile to be measured. The instrument is installed in standard grooved inclinometer casing. See Figure 1.

Plan View

Sensor Housing

Stationary Wheel

Spring Tensioned Wheel

Connecting Tube

Inclinometer Casing

Instrument Cable

Figure 1 - Model 6300 Tilt Sensor Assembly

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1.1. Tilt Sensor Construction The sensor comprises a pendulous mass which is supported by a vibrating wire strain gage and an elastic hinge. See Figure 2. The strain gage senses the changes in force caused by rotation of the center of gravity of the mass. The mass and sensor are enclosed in a waterproof housing which includes components for connecting the sensor to wheel assemblies and/or other sensors. The wheel assemblies centralize the sensors and allow the assembly to be lowered into the casing. Swivel joints are included to prevent the wheel assemblies from running out of the casing grooves due to spiral problems. Stainless steel tubing is used to connect the transducer and wheel assemblies together, and the whole string is normally supported from the top of the casing. Biaxial systems use two transducers mounted at 90 to each other.

Figure 2 - Model 6300 Tilt Sensor To prevent damage during shipment the tilt sensors are locked in place by means of a locking clamp screw. This slotted-head clamp screw must be removed and replaced by a Phillips-head seal screw, (provided in the zip-lock bag), to render the tiltmeter operative.

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2. INSTALLATION 2.1. Preliminary Tests

Top Support

Protective Cap

Gage Cable

Inclinometer

Wheel Assembly

Sensor Assembly

Gage Tubing

Bottom Cap

Cable Connector

Casing

Prior to installation, the sensors need to be checked for proper operation. Each tilt sensor is supplied with a calibration sheet that shows the relationship between readout digits and inclination. The tilt sensor electrical leads (usually the red and black leads) are connected to a readout box (see section 3) and the current reading compared to the calibration readings. After backing-off the clamp screw 3 full turns, carefully position the sensor against a vertical surface and observe the reading. It will take a few seconds to come to equilibrium and the sensor must be held in a steady position. The readings should be within +/- 200 digits of the factory reading, re-tighten the clamp screw 3 turns.

Note: Vibrating wire tilt sensors are shock sensitive and severe shocks can cause a permanent offset or even break

the suspension. (The unit will not survive a 2 ft. (.5 m) drop onto a hard surface). When transporting the tiltmeter

tighten the locking clamp screw.

Checks of electrical continuity can also be made using an ohmmeter. Resistance between the gage leads should be approximately 180 , ±10 ohms. Remember to add cable resistance when checking (22 AWG stranded copper leads are approximately 14.7/1000' or 48.5/km, multiply by 2 for both directions). Between the green and white should be approximately 3000 ohms at 25° (see Table B-1), and between any conductor and the shield should exceed 2 megohm.

2.2. Model 6300 Assembly and Installation

1. Connect the safety cable to the bottom wheel assembly. (See Figure 3) This is strongly recommended. Not only can it be used to retrieve the assembly in the event that one of the joints breaks loose, but it is also very useful in lowering the assembly into the casing. The alternative is to hold the tube sections with vice-grips at the top of the casing.

The bottom anchor is labeled and has no Universal joint, just the swivel. The safety cable has a loop at its bottom end which fits over the long bolt used to hold the bottom anchor to the first tube section. This is shown in Figure 3. The cable eyebolt is trapped between two nuts.

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Figure 3. Bottom Wheel Assembly with Safety Cable

2. Connect the first length of gage tubing to the bottom wheel assembly. The length of tube is shown in the table supplied with this manual. (In some cases, two tubes are joined together by a special union.) Use the 10-32 screws and nuts, and a thread locking cement to make this joint.

3. The next step is to attach the uniaxial or biaxial sensor assembly. 2.2.1. Uniaxial System The uniaxial sensor is delivered unattached to its wheel assembly and should be attached using the two 10-32 nuts and cap screws supplied. The tongue of the sensor fits inside the slot of the wheel assembly with the orientation set such that the A+ direction marked on the sensor is aligned on the same side as the fixed wheel on the wheel assembly. Tilts in the positive direction yield increasing readings in digits. Vibrating wire tilt sensors are shipped with a clamp screw holding the internal pendulum mechanism so that it is not damaged in shipment. A label is attached to each sensor emphasizing the importance of removing the slotted-head clamp screw completely and replacing it with the Phillips-head seal screw taped to the sensor. (Extra seal screws are provided in a zip-lock bag along with other accessories in case some become lost). This is very important for the sensor to be able to respond to tilting and remain waterproof. The sensor and wheel assembly is now attached to the first tube section using a single long 10-32 capscrew. (Use Loctite222 on all threads)

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2.2.2. Biaxial System The biaxial sensors are delivered unattached to the wheel assembly and to each other. The upper sensor should be attached to the wheel assembly using the two 10-32 nuts and cap screws supplied. The tongue of the sensor fits inside the slot of the wheel assembly with the orientation set such that the A+ direction marked on the sensor is aligned on the same side as the fixed wheel on the wheel assembly. (Tilts in the positive direction yield increasing readings in digits). The adaptor piece is now bolted to the bottom of the sensor using a single 10-32 cap screw and thread locking compound (Loctite 222)

Figure 4. Biaxial sensor assembly

Two short cap screws are used to attach the lower sensor via this adaptor with its positive direction (Marked A+ on the sensor body) at 90° clockwise from the upper sensor (in plan looking down the casing). This will be the B+ direction. See Figure 5.

Fixed Wheel

Instrument Cable

A+

B+

Instrument Cable

Figure 5 - Biaxial Sensor Orientation Note that there is some clearance around the bolt holes which will allow for some manual alignment of the sensors (absolute alignment is not critical). When the two sensors are connected, the lower one is joined to the previously prepared gage tube. Vibrating wire tilt sensors are shipped with a clamp screw holding the internal pendulum mechanism so that it is not damaged in shipment. A label is attached to each sensor emphasizing the importance of removing the slotted-head clamp screw completely and replacing it with the Phillips-head seal screw taped to the sensor. (Extra seal screws are provided in a zip-lock bag along with other accessories in case some become lost). This is very important for the sensor to be able to respond to tilting and remain waterproof.

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This assembly is now lowered into the borehole, using the safety cable, with the upper assembly fixed wheel aligned in the so-called A+ direction. It is customary (and recommended) to point the A+ direction in the same direction as the anticipated movement, i.e , towards the excavation being monitored or down-slope in the case of slope stability applications. Be sure that the lower wheel assembly and swivel are also aligned this way. While holding the assembly at the top of the casing, using either the safety cable or vice grips on the tubing, the next segment with sensors, wheels and swivel are attached and lowered in the same orientation. The system can become quite heavy and a clamp of some sort may need to be used to hold the rods in place while being assembled. The use of a winch to hold the safety cable can be a help. Note that the longer cables are on reels to facilitate handling. Something like two little saw horses (or even folding chairs) with a broom stick across them to act as an axle will allow the cable to spool off as needed and provide a storage point for the rest of the cable. The cables from the lower sensors should be taped or tie-wrapped to the assembly at intervals to support them as the system is built up and lowered down the borehole. Continue to add gage tubing, sensors and wheel assemblies until the last sensor has been attached to the upper wheel assembly, which is pre-assembled to the top suspension. (See figure 6). The Top suspension can then lowered into position on the casing. It is important that the end of the casing be cut square to prevent any side pressure on the upper sensor wheel assembly.

Figure 6 Top Suspension

After the sensor string has been lowered into position, the safety cable can be tied off around the top of the casing and the signal cables can be run to the readout location and terminated or otherwise fixed. Readings should be taken immediately after installation, but it is recommended that the system be allowed to stabilise for a few hours before recording zero conditions. For IPI strings that are going to measure only across a subsurface zone of interest and will not reach the surface, the cross-piece of the top suspension is omitted and the IPI string is suspended at the proper depth by a length of aircraft cable, attached to the eyebolt, and tied off at the top of the casing.

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2.3. Fluid Damping The vibrating wire tilt sensor acts as a self-damping system when used in vibration free environments. When external ground or structural vibrations exceed a certain threshold, the pendulous mass will continue to "dither" and stable readings may not be possible. In such cases, additional damping can be achieved by adding a viscous damping fluid to a small reservoir contained in the sensor. A thin, wide "paddle" is connected to the mass and when the fluid is added the pendulum is damped by the action of the paddle in the damping fluid. Most in-place installations will not require this fluid. However, if the instrument gives unstable outputs, or it is known that the structure is constantly vibrating, the fluid can be added. The fluid is a high-viscosity silicone oil which must be injected into the sensor with a syringe. The sensor must be held upright during the injection of the fluid and at all times following the injection. This makes it necessary to perform this operation in the field. The following applies for a typical in-place installation.

1. After connecting the sensor to the gage tubing already in the casing, and after removal of the clamping screw, use the syringe applied, first pull the piston from the syringe and squeeze the silicone from the tube into the syringe. Replace the piston and start the silicone oil out of the "needle" end.

3. Now, inject 2.00cc into the hole in the sensor. Immediately following this operation, the seal screw should be replaced in the sensor.

4. The sensor may now be lowered into the casing. 2.4. Splicing and Junction Boxes Because the vibrating wire output signal is a frequency rather than current or voltage, variations in cable resistance have little effect on gage readings and, therefore, splicing of cables has little effect and, in some case, may be beneficial. For example, if multiple sensors are installed in a borehole, and the distance from the borehole to the terminal box or datalogger is great, a splice could be made to connect the individual cables to a single multi-conductor cable. This multiconductor cable would then be run to the readout station. For such installations it is recommended that the transducer be supplied with enough cable to reach the top of the casing plus enough extra to make splicing possible. The cable used for making splices should be a high quality twisted pair type with 100% shielding (with integral shield drain wire). When splicing, it is very important that the shield drain wires be spliced together! Splice kits recommended by Geokon (i.e. 3M Scotchcast, model 82-A1) incorporate casts placed around the splice then filled with epoxy to waterproof the connections. When properly made, this type of splice is equal or superior to the cable itself in strength and electrical properties. Contact Geokon for splicing materials and additional cable splicing instructions. Junction boxes and terminal boxes are available from Geokon for all types of applications. In addition, portable readout equipment and datalogging hardware are available. Contact Geokon for specific application information.

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3. TAKING READINGS 3.1. Operation of the GK-403 Readout Box The GK-403 can store gage readings and also apply calibration factors to convert readings to engineering units. Consult the GK-403 Instruction Manual for additional information on Mode "G" of the Readout. The following instructions will explain taking gage measurements using Mode "B". Connect the Readout using the flying leads or in the case of a terminal station, with a connector. The red and black clips are for the vibrating wire gage, the white and green clips are for the thermistor and the blue for the shield drain wire. 1. Turn the display selector to position "B". Readout is in digits (Equation 1). 2. Turn the unit on and a reading will appear in the front display window. The last digit may

change one or two digits while reading. Press the "Store" button to record the value displayed. If the no reading displays or the reading is unstable see section 5 for troubleshooting suggestions. The thermistor will be read and output directly in degrees centigrade.

3. The unit will automatically turn itself off after approximately 2 minutes to conserve

power.

3.2 Operation of the GK404 Readout Box The GK404 is a palm sized readout box which displays the Vibrating wire value and the temperature in degrees centigrade. The GK-404 Vibrating Wire Readout arrives with a patch cord for connecting to the vibrating wire gages. One end will consist of a 5-pin plug for connecting to the respective socket on the bottom of the GK-404 enclosure. The other end will consist of 5 leads terminated with alligator clips. Note the colors of the alligator clips are red, black, green, white and blue. The colors represent the positive vibrating wire gage lead (red), negative vibrating wire gage lead (black), positive thermistor lead (green), negative thermistor lead (white) and transducer cable drain wire (blue). The clips should be connected to their respectively colored leads from the vibrating wire gage cable. Use the POS (Position) button to select position B and the MODE button to select Dg (digits). Other functions can be selected as described in the GK404 Manual. The GK-404 will continue to take measurements and display the readings until the OFF button is pushed, or if enabled, when the automatic Power-Off timer shuts the GK-404 off. The GK-404 continuously monitors the status of the (2) 1.5V AA cells, and when their combined voltage drops to 2V, the message Batteries Low is displayed on the screen. A fresh set of 1.5V AA batteries should be installed at this point

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3.3. MICRO-10 Datalogger The following parameters are recommended when using the Model 6350 with the MICRO-10 datalogger or any other CR10 based datalogger: Excitation - The 2.5V excitation directly off the wiring panel is ideal for these sensors. The 5 volt supply from the AVW-1 and AVW-4 modules is also usable, but the 12V excitation should be avoided as it tends to overdrive the sensor. The default excitation voltage used in MICRO-10 systems is 5V. Excitation Frequency - The starting and ending frequencies of the excitation sweep should be kept in a relatively narrow band for these sensors to maximize the stability and resolution of the output. The exact values can be calculated for a given sensor from the supplied calibration sheet. Ideally one could calculate settings by taking an initial reading and then setting the starting frequency to 200 Hz below and the ending frequency 200 Hz above. Alternately, the low end frequency sweep setting should be set to 14 (1400 Hz), the high end, 35 (3500 Hz). 3.4. Measuring Temperature Each vibrating wire tilt sensor is equipped with a thermistor for reading temperature. The thermistor gives a varying resistance output as the temperature changes. Usually the white and green leads are connected to the internal thermistor. 1. If using an ohmmeter, connect an ohmmeter to the two thermistor leads coming from the tilt

sensor. (Since the resistance changes with temperature are so large, the effect of cable resistance is usually insignificant.)

2. Look up the temperature for the measured resistance in Table B-1. Alternately the

temperature could be calculated using Equation B-1. Note: The GK-403 and the Gk 404 readout boxes will read the thermistor and display temperature in C automatically.

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4. DATA REDUCTION 4.1. Inclination Calculation Inclinations are measured in digits on Position B on the GK-401, GK-403 or GK404 Readout Box. The output of the VW tilt sensor is proportional to the sine of the angle of tilt. For small angles and sin are the same, so the relationship between output digits and the amount of tilting, (change of the angle of inclination), , is given by the equation:

= sin = (R1 R0) G degrees tilt

Equation 1 Calculation of Tilt (Linear). Where: R1 is the current reading in digits Ro is the initial reading in digits and G is the Linear Gage Factor in degrees tilt/digit given on the Calibration Sheet supplied with the sensor. The linear equation works very well for inclinations of less than four degrees. More than this and the linearity errors start to increase beyond 0.5%FS. The error incurred by using the linear equation is shown on the calibration chart. For better accuracy at larger inclinations use the polynomial equation: This uses a second order curve to approximate the sine curve.

= R2A + RB + C degrees tilt

Equation 2 Calculation of Tilt (Polynomial).

Where A, B and C are the coefficients supplied on the calibration sheet. Calculate 1 by substituting R = R1 in the formula and then calculate 0 by substituting R = R0 then subtract to find the difference = (1 - 0). 4.2. Temperature Correction The Model 6350 Tiltmeter has a slight temperature sensitivity on the order of -0.5 digit per °C rise, i.e. the reading falls by 0.5 digits for every 1°C rise of temperature. The temperature correction is:

+0.5G(T1-T0) degrees tilt

Equation 3 Temperature Correction

Normally, corrections are not applied for this small effect because the structure being monitored usually is affected to a much greater degree. An important point to note, also, is that sudden changes in temperature will cause both the structure and the Tiltmeter to undergo transitory physical changes that will show up in the readings. The gage temperature should always be recorded for comparison, and efforts should be made to obtain readings when the instrument and structure are at thermal equilibrium. The best time for this tends to be in the late evening or early morning hours.

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4.3. Deflection Calculation Now, the change in reading must be converted to a lateral deflection. The lateral deflection is defined as Lsin where L is the gage length between pivot points and is the change in inclination determined from Equation 3. The length L1, L2, L3,…. etc., can be calculated by adding 311mm,(uniaxial systems) or 524mm, (biaxial system), to the individual lengths of tubing. This will give the correct distance between pivot points. The horizontal displacement profile can be constructed by using the cumulative sum of the displacement starting with the bottom segment. Subsequent readings over time will reveal changes in deflection, possible shear zones, etc. For example, referring to Figure 5 and Equation 4. D1 = L1 sin1

D2 = L1 sin1 + L2 sin2

D3 = L1 sin1 + L2 sin2 + L3 sin3

D4 = L1 sin1 + L2 sin2 + L3 sin3 + L4 sin4

D5 = L1 sin1 + L2 sin2 + L3 sin3 + L4 sin4 +L5 sin5

Where, for small angles sin = (R1 R0) G

Equation 4 – Horizontal Displacement Calculation

Although the system is designed for use with continuous segments and pivots, the sensors can be installed without interconnecting tubing in standard, round tubing or pipe using special friction anchoring. In those systems, the assumption is made that the measured deflection occurs over the segment length and that L is the distance between sensors. 4.4. Environmental Factors Since the purpose of the inclinometer installation is to monitor site conditions, factors that may affect these conditions should be observed and recorded. Seemingly minor effects may have a real influence on the behavior of the structure being monitored and may give an early indication of potential problems. Some of these factors include, but are not limited to: blasting, rainfall, tidal or reservoir levels, excavation and fill levels and sequences, traffic, temperature and barometric changes, changes in personnel, nearby construction activities, seasonal changes, etc.

L1

L4

L3

L5

L2

D5

Figure 7 - Deflection Intervals

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Figure 7 - Sample Model 6300 Calibration Sheet

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5. TROUBLESHOOTING Maintenance and troubleshooting of the vibrating wire tilt sensors used in the Model 6300 Inclinometer are is confined to periodic checks of cable connections. The sensors are sealed and there are no user-servicable parts. Consult the following list of problems and possible solutions should difficulties arise. Consult the factory for additional troubleshooting help. Symptom: Tilt Sensor Readings are Unstable

Is the readout box position set correctly? If using a datalogger to record readings automatically are the swept frequency excitation settings correct? Channel A of the GK-401 and GK-403 can be used to read the tilt sensor. To convert the Channel A period display to digits use Equation 1.

Is there a source of electrical noise nearby? Most probable sources of electrical noise are motors, generators and antennas. Make sure the shield drain wire is connected to ground whether using a portable readout or datalogger. If using the GK-401 Readout connect the clip with the green boot to the bare shield drain wire of the tilt sensor cable. If using the GK-403 connect the clip with the blue boot to the shield drain wire.

Does the readout work with another tilt sensor? If not, the readout may have a low battery or be malfunctioning.

Symptom: Tilt Sensor Fails to Read

Is the cable cut or crushed? This can be checked with an ohmmeter. Nominal resistance between the two gage leads (usually red and black leads) is 180, 10. Remember to add cable resistance when checking (22 AWG stranded copper leads are approximately 14.7/1000' or 48.5/km, multiply by 2 for both directions). If the resistance reads infinite, or very high (megohms), a cut wire must be suspected. If the resistance reads very low (20) a short in the cable is likely.

Does the readout or datalogger work with another tilt sensor? If not, the readout or datalogger may be malfunctioning.

Symptom: Thermistor resistance is too high.

Is there an open circuit? Check all connections, terminals and plugs. If a cut is located in the cable, splice according to instructions in Section 2.3.

Symptom: Thermistor resistance is too low.

Is there a short? Check all connections, terminals and plugs. If a short is located in the cable, splice according to instructions in Section 2.3.

Water may have penetrated the interior of the tilt sensor. There is no remedial action.

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APPENDIX A - SPECIFICATIONS A.1. Vibrating Wire Tilt Sensor

Model: 6300 Range:¹ 10°

Resolution:² 8 arc seconds Accuracy:³ +/- 8 arc seconds Linearity: 4 +/- 0.3% FSR

Thermal Zero Shift: 4 arc seconds/C Operating Temperature -40 to +80° C

-40 to 175° F Operating Frequency: 1400-3500 Hz

Coil Resistance: 180 Diameter: 1.250", 32 mm

Length: 7.375", 187 mm Weight: 1.5 lbs., 0.7 kg.

Materials: 304 Stainles Steel Electrical Cable: 2 twisted pair (4 conductor) 22 AWG

Foil shield, PVC jacket, nominal OD=6.3 mm (0.250")

Table A-1 Model 6300 Tilt Sensor Specifications Notes: ¹ Consult the factory for other ranges. ² Depends on readout equipment. With averaging techniques it is possible to achieve 1 arc seco ³ Derived using 2nd order polynomial. 4 The output from the sensor is proportional to the sine of the angle of tilt A.2. Thermistor (see Appendix B also) Range: -80 to +150° C Accuracy: ±0.5° C

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APPENDIX B - THERMISTOR TEMPERATURE DERIVATION Thermistor Type: YSI 44005, Dale #1C3001-B3, Alpha #13A3001-B3 Resistance to Temperature Equation:

TA B LnR C LnR

1

27323( ) ( ).

Equation B-1 Convert Thermistor Resistance to Temperature

Where; T Temperature in C. LnR Natural Log of Thermistor Resistance A 1.4051 10-3 (coefficients calculated over the 50 to +150 C. span) B 2.369 10-4 C 1.019 10-7

Ohms Temp Ohms Temp Ohms Temp Ohms Temp Ohms Temp 201.1K -50 16.60K -10 2417 30 525.4 70 153.2 110 187.3K -49 15.72K -9 2317 31 507.8 71 149.0 111 174.5K -48 14.90K -8 2221 32 490.9 72 145.0 112 162.7K -47 14.12K -7 2130 33 474.7 73 141.1 113 151.7K -46 13.39K -6 2042 34 459.0 74 137.2 114 141.6K -45 12.70K -5 1959 35 444.0 75 133.6 115 132.2K -44 12.05K -4 1880 36 429.5 76 130.0 116 123.5K -43 11.44K -3 1805 37 415.6 77 126.5 117 115.4K -42 10.86K -2 1733 38 402.2 78 123.2 118 107.9K -41 10.31K -1 1664 39 389.3 79 119.9 119 101.0K -40 9796 0 1598 40 376.9 80 116.8 120 94.48K -39 9310 1 1535 41 364.9 81 113.8 121 88.46K -38 8851 2 1475 42 353.4 82 110.8 122 82.87K -37 8417 3 1418 43 342.2 83 107.9 123 77.66K -36 8006 4 1363 44 331.5 84 105.2 124 72.81K -35 7618 5 1310 45 321.2 85 102.5 125 68.30K -34 7252 6 1260 46 311.3 86 99.9 126 64.09K -33 6905 7 1212 47 301.7 87 97.3 127 60.17K -32 6576 8 1167 48 292.4 88 94.9 128 56.51K -31 6265 9 1123 49 283.5 89 92.5 129 53.10K -30 5971 10 1081 50 274.9 90 90.2 130 49.91K -29 5692 11 1040 51 266.6 91 87.9 131 46.94K -28 5427 12 1002 52 258.6 92 85.7 132 44.16K -27 5177 13 965.0 53 250.9 93 83.6 133 41.56K -26 4939 14 929.6 54 243.4 94 81.6 134 39.13K -25 4714 15 895.8 55 236.2 95 79.6 135 36.86K -24 4500 16 863.3 56 229.3 96 77.6 136 34.73K -23 4297 17 832.2 57 222.6 97 75.8 137 32.74K -22 4105 18 802.3 58 216.1 98 73.9 138 30.87K -21 3922 19 773.7 59 209.8 99 72.2 139 29.13K -20 3748 20 746.3 60 203.8 100 70.4 140 27.49K -19 3583 21 719.9 61 197.9 101 68.8 141 25.95K -18 3426 22 694.7 62 192.2 102 67.1 142 24.51K -17 3277 23 670.4 63 186.8 103 65.5 143 23.16K -16 3135 24 647.1 64 181.5 104 64.0 144 21.89K -15 3000 25 624.7 65 176.4 105 62.5 145 20.70K -14 2872 26 603.3 66 171.4 106 61.1 146 19.58K -13 2750 27 582.6 67 166.7 107 59.6 147 18.52K -12 2633 28 562.8 68 162.0 108 58.3 148 17.53K -11 2523 29 543.7 69 157.6 109 56.8 149 55.6 150

Table B-1 Thermistor Resistance versus Temperature

16

APPENDIX C - EXCITATION AND READOUT PARAMETERS Model 6300 with Micro-10 Datalogger The Micro-10 Datalogger which uses the Campbell Scientific Measurement and Control Module can be used to continuously monitor the Model 6300. The following parameters are recommended: Excitation The 2.5 volt excitation directly off the wiring panel is ideal for these sensors. The 5 volt supply from the AVW-1 and AVW-4 modules is also usable, but the 12 volt excitation should be avoided as it tends to overdrive the sensor. Excitation Frequency The starting and ending frequencies of the excitation sweep should be kept in a relatively narrow band for these sensors to maximize the stability and resolution of the output. The frequency band for the full range is shown on the calibration sheets. The frequencies can be determined from these. The highest and lowest frequencies shown can be used to determine the sweep parameters. After initial readings are obtained, parameters should be set to 200 Hz below the resonant frequency and 1-200 Hz above. Offset In order to maximize the 5 digit, high resolution output, the offset parameter can be used to remove the zero offset of the sensor. In other words, if the installed reading is 4,300, the offset parameter could be set at -4300 which would theoretically change the resolution from 0.1 digit to 0.0001 digit. For assistance in programming these parameters contact Geokon, Inc.

17

Appendix D - Addressable Systems

The Addressable system allows all the borehole sensors to be connected to a single cable rather than have a separate cable for each sensor. The sensors are supplied in a string connected together by pre-determined lengths of cables specified by the customer. The string of sensor is installed in a manner to that described in Section 2. The cable is connected, via a 15 pin connector, to a special Geokon Model 8021-1X datalogger modified, by the addition of a Model 8031 Distributed Multiplexer, specifically for use with the addressable system

Using the 8031 Distributed Multiplexer

Description: The 8031 Distributed Multiplexer is a device that allows up to 256 individual VW transducers or MEMS type inclinometers (6001 or 6150) – both unidirectional and bidirectional - to be connected as “drops” off of a single bus. Each 8031 is addressed via RS-485 level ENABLE and CLOCK signals in the same manner as the Geokon model 8032 Multiplexer. Two modes of channel selection (clocking) are available: 1) 16 channel mode (two clock pulses per channel): This is the standard configuration, and uses the same ENABLE and CLOCK timing requirements as the Geokon model 8032 multiplexer in 16 channel mode. 2) 32 channel mode (one clock pulse per channel). This is a custom configuration, and uses the same ENABLE and CLOCK timing requirements as the Geokon model 8032 multiplexer in 32 channel mode. Notify Geokon when ordering if this one clock pulse per channel version will be required. The 8031 may be used with either the Micro-10 Datalogger (for both 6150/6001MEMS or VW transducers), the GK-403 VW Readout (VW transducers only) or any Data Acquisition System capable of providing the required ENABLE and CLOCK control signals. The 8031 circuit board may be mounted in the transducer housing, with its individual 1 of 256 channel address being set by on-board DIP switches. Depending on the application, a single 4, 5 or 6 twisted pair cable may be used to connect all of the 8031’s and their associated transducers to the Micro-10, GK-403 or other Data Acquisition System. The 8031 circuit board incorporates RC snubbers across the relay contacts to prevent contact arcing in power switching applications. If being used with VW, these snubber components (R3-R8 and C1-C6) will need to be removed.

18

Circuit Board Connector Pin-outs: Connector Pin Signal Description J2 1 +12V NET +12V Power from the bus cable (twisted pair 1) 2 GND NET Power Ground from the bus cable (twisted pair 1) 3 RESET NET RS-485 RESET from the bus cable (twisted pair 2) 4 /RESET NET RS-485 /RESET from the bus cable (twisted pair 2) 5 CLOCK NET RS-485 CLOCK from the bus cable (twisted pair 3) 6 /CLOCK NET RS-485 /CLOCK from the bus cable (twisted pair 3)

J7 1 THERM+ NET Thermistor (+) from the bus cable (twisted pair 4) 2 THERM- NET Thermistor (–) from the bus cable (twisted pair 4) 3 VA+/VW1+ NET 6001/6150 A axis (+) or VW1 (+)* from the bus cable (twisted pair 5) 4 VA- NET 6001/6150 A axis (–) from the bus cable (twisted pair 5) 5 VB+/VW1- NET 6001/6150 B axis (+) or VW1 (-)* from the bus cable (twisted pair 6) 6 VB- NET 6001/6150 B axis (–) from the bus cable (twisted pair 6) *Note: If VW is being used, combine VW1+ and VW1- into a twisted pair (twisted pair 5) – otherwise combine VA+/VA- into a twisted pair (twisted pair 5) and VB+/VB- into a twisted pair (twisted pair 6). J10 1 VW2+ NET VW2 (+) from the bus cable (twisted pair 6) 2 VW2- NET VW2 (-) from the bus cable (twisted pair 6) J5 1 VW1- Coil (-) from VW transducer #1 2 VW1+ Coil (+) from VW transducer #1 3 TH+ Therm (+) from VW transducer #1 4 TH- Therm (-) from VW transducer #1 J9 1 VW2- Coil (-) from VW transducer #2 2 VW2+ Coil (+) from VW transducer #2 J4 1 +12VX +12V Power to 6150-2 or 6001-2 board 2 GNDX Power Ground to 6150-2 or 6001-2 board 3 GNDA Analog Ground to 6150-2 or 6001-2 board 5 VA_IN Channel A output from 6150-2 or 6001-2 board 6 GNDA Analog Ground to 6150-2 or 6001-2 board J8 1 +12VX +12V Power to 6150-2 or 6001-2 board 2 GNDX Power Ground to 6150-2 or 6001-2 board 3 GNDA Analog Ground to 6150-2 or 6001-2 board 5 VB_IN Channel B output from 6150-2 or 6001-2 board 6 GNDA Analog Ground to 6150-2 or 6001-2 board

19

Circuit Board Jumper Settings: Jumper Position Description J1 & J6 1-2 Use this setting for 6150 and 6001 applications (default) 3-4 Use this setting for VW applications Circuit Board DIP Switch Settings: Switch Position Description SW1 (1&2) OFF Removes RS-485 termination resistors from the circuit. * (default) ON Adds RS-485 termination resistors to the circuit. * *Note: Keep SW1 OFF for all 8031’s except the last one physically on the bus (the one furthest from the datalogger or GK-403).

20

SW2 Address Table: (channel 1 default)

SW1 POSITION Channel 1 2 3 4 5 6 7 8

1 OFF OFF OFF OFF OFF OFF OFF ON 2 OFF OFF OFF OFF OFF OFF ON OFF 3 OFF OFF OFF OFF OFF OFF ON ON 4 OFF OFF OFF OFF OFF ON OFF OFF 5 OFF OFF OFF OFF OFF ON OFF ON 6 OFF OFF OFF OFF OFF ON ON OFF 7 OFF OFF OFF OFF OFF ON ON ON 8 OFF OFF OFF OFF ON OFF OFF OFF 9 OFF OFF OFF OFF ON OFF OFF ON

10 OFF OFF OFF OFF ON OFF ON OFF 11 OFF OFF OFF OFF ON OFF ON ON 12 OFF OFF OFF OFF ON ON OFF OFF 13 OFF OFF OFF OFF ON ON OFF ON 14 OFF OFF OFF OFF ON ON ON OFF 15 OFF OFF OFF OFF ON ON ON ON 16 OFF OFF OFF ON OFF OFF OFF OFF 17 OFF OFF OFF ON OFF OFF OFF ON 18 OFF OFF OFF ON OFF OFF ON OFF 19 OFF OFF OFF ON OFF OFF ON ON 20 OFF OFF OFF ON OFF ON OFF OFF 21 OFF OFF OFF ON OFF ON OFF ON 22 OFF OFF OFF ON OFF ON ON OFF 23 OFF OFF OFF ON OFF ON ON ON 24 OFF OFF OFF ON ON OFF OFF OFF 25 OFF OFF OFF ON ON OFF OFF ON 26 OFF OFF OFF ON ON OFF ON OFF 27 OFF OFF OFF ON ON OFF ON ON 28 OFF OFF OFF ON ON ON OFF OFF 29 OFF OFF OFF ON ON ON OFF ON 30 OFF OFF OFF ON ON ON ON OFF 31 OFF OFF OFF ON ON ON ON ON 32 OFF OFF ON OFF OFF OFF OFF OFF 33 OFF OFF ON OFF OFF OFF OFF ON 34 OFF OFF ON OFF OFF OFF ON OFF 35 OFF OFF ON OFF OFF OFF ON ON 36 OFF OFF ON OFF OFF ON OFF OFF 37 OFF OFF ON OFF OFF ON OFF ON 38 OFF OFF ON OFF OFF ON ON OFF 39 OFF OFF ON OFF OFF ON ON ON 40 OFF OFF ON OFF ON OFF OFF OFF 41 OFF OFF ON OFF ON OFF OFF ON 42 OFF OFF ON OFF ON OFF ON OFF 43 OFF OFF ON OFF ON OFF ON ON 44 OFF OFF ON OFF ON ON OFF OFF 45 OFF OFF ON OFF ON ON OFF ON 46 OFF OFF ON OFF ON ON ON OFF 47 OFF OFF ON OFF ON ON ON ON 48 OFF OFF ON ON OFF OFF OFF OFF 49 OFF OFF ON ON OFF OFF OFF ON 50 OFF OFF ON ON OFF OFF ON OFF 51 OFF OFF ON ON OFF OFF ON ON 52 OFF OFF ON ON OFF ON OFF OFF 53 OFF OFF ON ON OFF ON OFF ON 54 OFF OFF ON ON OFF ON ON OFF 55 OFF OFF ON ON OFF ON ON ON 56 OFF OFF ON ON ON OFF OFF OFF 57 OFF OFF ON ON ON OFF OFF ON 58 OFF OFF ON ON ON OFF ON OFF 59 OFF OFF ON ON ON OFF ON ON 60 OFF OFF ON ON ON ON OFF OFF 61 OFF OFF ON ON ON ON OFF ON 62 OFF OFF ON ON ON ON ON OFF 63 OFF OFF ON ON ON ON ON ON 64 OFF ON OFF OFF OFF OFF OFF OFF 65 OFF ON OFF OFF OFF OFF OFF ON 66 OFF ON OFF OFF OFF OFF ON OFF 67 OFF ON OFF OFF OFF OFF ON ON 68 OFF ON OFF OFF OFF ON OFF OFF 69 OFF ON OFF OFF OFF ON OFF ON

21 SW1 POSITION

Channel 1 2 3 4 5 6 7 8 70 OFF ON OFF OFF OFF ON ON OFF 71 OFF ON OFF OFF OFF ON ON ON 72 OFF ON OFF OFF ON OFF OFF OFF 73 OFF ON OFF OFF ON OFF OFF ON 74 OFF ON OFF OFF ON OFF ON OFF 75 OFF ON OFF OFF ON OFF ON ON 76 OFF ON OFF OFF ON ON OFF OFF 77 OFF ON OFF OFF ON ON OFF ON 78 OFF ON OFF OFF ON ON ON OFF 79 OFF ON OFF OFF ON ON ON ON 80 OFF ON OFF ON OFF OFF OFF OFF 81 OFF ON OFF ON OFF OFF OFF ON 82 OFF ON OFF ON OFF OFF ON OFF 83 OFF ON OFF ON OFF OFF ON ON 84 OFF ON OFF ON OFF ON OFF OFF 85 OFF ON OFF ON OFF ON OFF ON 86 OFF ON OFF ON OFF ON ON OFF 87 OFF ON OFF ON OFF ON ON ON 88 OFF ON OFF ON ON OFF OFF OFF 89 OFF ON OFF ON ON OFF OFF ON 90 OFF ON OFF ON ON OFF ON OFF 91 OFF ON OFF ON ON OFF ON ON 92 OFF ON OFF ON ON ON OFF OFF 93 OFF ON OFF ON ON ON OFF ON 94 OFF ON OFF ON ON ON ON OFF 95 OFF ON OFF ON ON ON ON ON 96 OFF ON ON OFF OFF OFF OFF OFF 97 OFF ON ON OFF OFF OFF OFF ON 98 OFF ON ON OFF OFF OFF ON OFF 99 OFF ON ON OFF OFF OFF ON ON

100 OFF ON ON OFF OFF ON OFF OFF 101 OFF ON ON OFF OFF ON OFF ON 102 OFF ON ON OFF OFF ON ON OFF 103 OFF ON ON OFF OFF ON ON ON 104 OFF ON ON OFF ON OFF OFF OFF 105 OFF ON ON OFF ON OFF OFF ON 106 OFF ON ON OFF ON OFF ON OFF 107 OFF ON ON OFF ON OFF ON ON 108 OFF ON ON OFF ON ON OFF OFF 109 OFF ON ON OFF ON ON OFF ON 110 OFF ON ON OFF ON ON ON OFF 111 OFF ON ON OFF ON ON ON ON 112 OFF ON ON ON OFF OFF OFF OFF 113 OFF ON ON ON OFF OFF OFF ON 114 OFF ON ON ON OFF OFF ON OFF 115 OFF ON ON ON OFF OFF ON ON 116 OFF ON ON ON OFF ON OFF OFF 117 OFF ON ON ON OFF ON OFF ON 118 OFF ON ON ON OFF ON ON OFF 119 OFF ON ON ON OFF ON ON ON 120 OFF ON ON ON ON OFF OFF OFF 121 OFF ON ON ON ON OFF OFF ON 122 OFF ON ON ON ON OFF ON OFF 123 OFF ON ON ON ON OFF ON ON 124 OFF ON ON ON ON ON OFF OFF 125 OFF ON ON ON ON ON OFF ON 126 OFF ON ON ON ON ON ON OFF 127 OFF ON ON ON ON ON ON ON 128 ON OFF OFF OFF OFF OFF OFF OFF 129 ON OFF OFF OFF OFF OFF OFF ON 130 ON OFF OFF OFF OFF OFF ON OFF 131 ON OFF OFF OFF OFF OFF ON ON 132 ON OFF OFF OFF OFF ON OFF OFF 133 ON OFF OFF OFF OFF ON OFF ON 134 ON OFF OFF OFF OFF ON ON OFF 135 ON OFF OFF OFF OFF ON ON ON 136 ON OFF OFF OFF ON OFF OFF OFF 137 ON OFF OFF OFF ON OFF OFF ON 138 ON OFF OFF OFF ON OFF ON OFF 139 ON OFF OFF OFF ON OFF ON ON 140 ON OFF OFF OFF ON ON OFF OFF 141 ON OFF OFF OFF ON ON OFF ON 142 ON OFF OFF OFF ON ON ON OFF 143 ON OFF OFF OFF ON ON ON ON

22 SW1 POSITION

Channel 1 2 3 4 5 6 7 8 144 ON OFF OFF ON OFF OFF OFF OFF 145 ON OFF OFF ON OFF OFF OFF ON 146 ON OFF OFF ON OFF OFF ON OFF 147 ON OFF OFF ON OFF OFF ON ON 148 ON OFF OFF ON OFF ON OFF OFF 149 ON OFF OFF ON OFF ON OFF ON 150 ON OFF OFF ON OFF ON ON OFF 151 ON OFF OFF ON OFF ON ON ON 152 ON OFF OFF ON ON OFF OFF OFF 153 ON OFF OFF ON ON OFF OFF ON 154 ON OFF OFF ON ON OFF ON OFF 155 ON OFF OFF ON ON OFF ON ON 156 ON OFF OFF ON ON ON OFF OFF 157 ON OFF OFF ON ON ON OFF ON 158 ON OFF OFF ON ON ON ON OFF 159 ON OFF OFF ON ON ON ON ON 160 ON OFF ON OFF OFF OFF OFF OFF 161 ON OFF ON OFF OFF OFF OFF ON 162 ON OFF ON OFF OFF OFF ON OFF 163 ON OFF ON OFF OFF OFF ON ON 164 ON OFF ON OFF OFF ON OFF OFF 165 ON OFF ON OFF OFF ON OFF ON 166 ON OFF ON OFF OFF ON ON OFF 167 ON OFF ON OFF OFF ON ON ON 168 ON OFF ON OFF ON OFF OFF OFF 169 ON OFF ON OFF ON OFF OFF ON 170 ON OFF ON OFF ON OFF ON OFF 171 ON OFF ON OFF ON OFF ON ON 172 ON OFF ON OFF ON ON OFF OFF 173 ON OFF ON OFF ON ON OFF ON 174 ON OFF ON OFF ON ON ON OFF 175 ON OFF ON OFF ON ON ON ON 176 ON OFF ON ON OFF OFF OFF OFF 177 ON OFF ON ON OFF OFF OFF ON 178 ON OFF ON ON OFF OFF ON OFF 179 ON OFF ON ON OFF OFF ON ON 180 ON OFF ON ON OFF ON OFF OFF 181 ON OFF ON ON OFF ON OFF ON 182 ON OFF ON ON OFF ON ON OFF 183 ON OFF ON ON OFF ON ON ON 184 ON OFF ON ON ON OFF OFF OFF 185 ON OFF ON ON ON OFF OFF ON 186 ON OFF ON ON ON OFF ON OFF 187 ON OFF ON ON ON OFF ON ON 188 ON OFF ON ON ON ON OFF OFF 189 ON OFF ON ON ON ON OFF ON 190 ON OFF ON ON ON ON ON OFF 191 ON OFF ON ON ON ON ON ON 192 ON ON OFF OFF OFF OFF OFF OFF 193 ON ON OFF OFF OFF OFF OFF ON 194 ON ON OFF OFF OFF OFF ON OFF 195 ON ON OFF OFF OFF OFF ON ON 196 ON ON OFF OFF OFF ON OFF OFF 197 ON ON OFF OFF OFF ON OFF ON 198 ON ON OFF OFF OFF ON ON OFF 199 ON ON OFF OFF OFF ON ON ON 200 ON ON OFF OFF ON OFF OFF OFF 201 ON ON OFF OFF ON OFF OFF ON 202 ON ON OFF OFF ON OFF ON OFF 203 ON ON OFF OFF ON OFF ON ON 204 ON ON OFF OFF ON ON OFF OFF 205 ON ON OFF OFF ON ON OFF ON 206 ON ON OFF OFF ON ON ON OFF 207 ON ON OFF OFF ON ON ON ON 208 ON ON OFF ON OFF OFF OFF OFF 209 ON ON OFF ON OFF OFF OFF ON 210 ON ON OFF ON OFF OFF ON OFF 211 ON ON OFF ON OFF OFF ON ON 212 ON ON OFF ON OFF ON OFF OFF 213 ON ON OFF ON OFF ON OFF ON 214 ON ON OFF ON OFF ON ON OFF 215 ON ON OFF ON OFF ON ON ON 216 ON ON OFF ON ON OFF OFF OFF 217 ON ON OFF ON ON OFF OFF ON

23

ON

ON

ON

ON

SW1 POSITION

ON

OFF

OFF

ON

Channel

250

1

ON

2

ON

3

ON

4

ON

5

ON

6

OFF

7

ON

8

OFF

218 ON ON OFF ON ON OFF ON OFF 219 ON ON OFF ON ON OFF ON ON 220 ON ON OFF ON ON ON OFF OFF 221 ON ON OFF ON ON ON OFF ON 222 ON ON OFF ON ON ON ON OFF 223 ON ON OFF ON ON ON ON ON 224 ON ON ON OFF OFF OFF OFF OFF 225 ON ON ON OFF OFF OFF OFF ON 226 ON ON ON OFF OFF OFF ON OFF 227 ON ON ON OFF OFF OFF ON ON 228 ON ON ON OFF OFF ON OFF OFF 229 ON ON ON OFF OFF ON OFF ON 230 ON ON ON OFF OFF ON ON OFF 231 ON ON ON OFF OFF ON ON ON 232 ON ON ON OFF ON OFF OFF OFF 233 ON ON ON OFF ON OFF OFF ON 234 ON ON ON OFF ON OFF ON OFF 235 ON ON ON OFF ON OFF ON ON 236 ON ON ON OFF ON ON OFF OFF 237 ON ON ON OFF ON ON OFF ON 238 ON ON ON OFF ON ON ON OFF 239 ON ON ON OFF ON ON ON ON 240 ON ON ON ON OFF OFF OFF OFF 241 ON ON ON ON OFF OFF OFF ON 242 ON ON ON ON OFF OFF ON OFF 243 ON ON ON ON OFF OFF ON ON 244 ON ON ON ON OFF ON OFF OFF 245 ON ON ON ON OFF ON OFF ON 246 ON ON ON ON OFF ON ON OFF 247 ON ON ON ON OFF ON ON ON 248 ON ON ON ON ON OFF OFF OFF 249

251 ON ON ON ON ON OFF ON ON 252 ON ON ON ON ON ON OFF OFF 253 ON ON ON ON ON ON OFF ON 254 ON ON ON ON ON ON ON OFF 255 ON ON ON ON ON ON ON ON 256 OFF OFF OFF OFF OFF OFF OFF OFF

Model 8031 Specifications: Board Dimensions: 4.5”(L) x 1.155”(W) x 0.4”(H) Power Requirements: +12V (+/- 3V) 110mA (max) when active 700uA (max) standby Operating Temperature: 0-70° C Contact Resistance: 100 mΩ (typ) Contact Breakdown Voltage: 1500 Vrms Relay open/close time: 4mS (max)

HIDROFLEX REV.0 ABRIL/2007

Saneamento Tanque de Polimeros Vazão em Calha Parshall Elevatórias

Mineração Nível do Britador Quaternário Tanque de Rejeitos

Metalurgia Tanques de Ácidos Silo de Cal

Farmacêutica Vazão em canal aberto Silo de Matéria Prima

Cimento Silo de Escória Silo de Calcário

Química Tanque de Cloreto Férrico Tanque de Ácido Sulfúrico

Petroquímica Óleo BPF Água de Separação

Têxtil Tanques de Tintas

Alimentícia Silo de Estocagem Tanques de Chocolate

Fertilizantes Silo de Estocagem Tripper de Armazenagem

Papel e Celulose Cavaco de Madeira Unidades de Papel reciclado

Açúcar e Álcool Silo de Açúcar Tanque de Melaço

Lubrificantes Tanques de Óleo Aditivo

Automotiva Silo de Cal Tanques de Químicos

Siderurgia Silo de Carvão Silo de Coque

TRANSMISSOR DE NÍVEL E VAZÃO POR ONDAS ACÚSTICAS

O novo HIDROFLEX II é um transmissor de nível por ondas acústicas de última geração, projetado para efetuar a medição e controle de nível em tanques ou silos, considerando as condições típicas do Brasil. Por se r um equipamento modular adapta-se facilmente as mais di versas condições de processo.

O HIDROFLEX II emite um pulso de ondas acústicas com alta potência que é refletido da superfície do mate rial a ser medido. O sinal refletido é processado usando um al goritmo específico que é capaz de distinguir o sinal corret o e rejeitar sinais falsos ou interferências. A transmissão de O ndas Acústicas de alta potência assegura perdas mínimas no ambiente onde o sensor está instalado. Devido a alt a potência do sinal emitido, perdas de sinal tem muit o menos efeito do que é visto em um equipamento ultrassônic o tradicional. Uma energia maior é emitida em consequ ência uma energia maior é recebida. Um circuito de recepç ão especialmente desenvolvido consegue identificar e monitorar sinais de baixa amplitude mesmo em ambien tes com alto nível de ruídos. O sensor tem compensação de temperatura com isso garantimos uma máxima precisão na leitura e saídas.

Com esta nova tecnologia, é possível medir com prec isão o nível em aplicações com espuma, pó em suspensão, va por e gases, restrições estas comuns aos medidores ultrassonicos tradicionais. O nível de pastas, lama s e líquidos até 13 metros, pode ser medido facilmente com a utilização do HIDROFLEX II.

Nesta nova versão é possível medir vazão em calhas, vertedores ou em qualquer outro elemento primário d e vazão em que a fórmula Q=K N E é aplicada.

A unidade eletrônica pode ser instalada remotamente a uma distância de até 500 metros do sensor, via um cabo coaxial especifico.

HIDROFLEX II

.

ESPECIFICAÇÕES TÉCNICAS DO

HIDROFLEX II

Estrada do Biguá, 43 - Alto da B. Vista - 20531-680 - Rio de Janeiro – RJ - Tel.: 55 (21) 2493-0588 - Fa x:55 (21)-2493-3056 Email: vendas@msinstrumentos.com.br / Web: www.msinstrumentos.com.br

UNIDADE ELETRÔNICA Alimentação Elétrica: 90 a 260 Vca ou 12 a 30 Vcc Consumo: <3W (24 Vcc) <10VA (240 Vac) Memória: Não volátil (sem bateria) Distancia ao Sensor: 500m Relés: 03 SPDT 240V / 0.5A - Não indutivo,

com controle de bombas Conexão Elétrica: Integral 3 x M16; Remoto 3 x M20, 1 x

16mm Saídas Analógicas: 4-20mA (750 ΩΩΩΩ/24 Vcc) Indicação: Display Alfanumérico de 12 dígitos,

x 2 linhas e LCD backlight. Interface: 4 teclas de membrana e/ou via PC Modos de Medição: Distância/ nível /nível vazio/ vo lume/

volume vazio/vazão Unidades: mm /cm /m Construção: Invólucro IP65/Nema4

SENSOR Faixa de Medição: 0,35 a 13m Resolução: 1mm Freqüência: 30 Khz Pressão de operação: +/- 7.5 PSI (0,5bar) Ângulo de Medição: 7.5º (sem cone focalizador) Precisão +/-0.25% fundo de escala Resolução +/- 3 mm Retardo 0 a 9999 segundos (tipo RC) Fail-Safe Selecionavel via Software Área Cega 0,35 m (14”) Linearização Até 20 pontos via software Temp. Operacional -40ºC a +80ºC Montagem ANSI, JIS ou DIN Flange; 4”/100mm

para 10”/250mm; Nipple 1” BPS

SOFTWARE GOSHAWK Uma poderosa ferramenta de calibração e diagnóstico s. Com o GOSHAWK podemos configurar remotamente e conhecer , em situações criticas de processo, como se comporta o perfil do eco dentro de tanques ou silos, possibilitando o melhor posicionamento do sensor. A configuração é feita de forma interativa entre usuário e o sistema, com o usuário respondendo ao menu de parâmetros.

Instruction Manual

Model 4999-12L/LE (LAB 3)

Lightning Arrestor Board

No part of this instruction manual may be reproduced, by any means, without the written consent of Geokon, Inc.

The information contained herein is believed to be accurate and reliable. However, Geokon, Inc. assumes no responsibility for errors, omissions or misinterpretation. The information herein is subject to change without

notification.

Copyright © 2003, 2004, 2005, 2006 by Geokon, Inc. (Doc Rev C, 10/06)

Warranty Statement

Geokon, Inc. warrants its products to be free of defects in materials and workmanship, under

normal use and service for a period of 13 months from date of purchase. If the unit should

malfunction, it must be returned to the factory for evaluation, freight prepaid. Upon examination

by Geokon, if the unit is found to be defective, it will be repaired or replaced at no charge.

However, the WARRANTY is VOID if the unit shows evidence of having been tampered with or

shows evidence of being damaged as a result of excessive corrosion or current, heat, moisture

or vibration, improper specification, misapplication, misuse or other operating conditions outside

of Geokon's control. Components which wear or which are damaged by misuse are not

warranted. This includes fuses and batteries.

Geokon manufactures scientific instruments whose misuse is potentially dangerous. The

instruments are intended to be installed and used only by qualified personnel. There are no

warranties except as stated herein. There are no other warranties, expressed or implied,

including but not limited to the implied warranties of merchantability and of fitness for a

particular purpose. Geokon, Inc. is not responsible for any damages or losses caused to other

equipment, whether direct, indirect, incidental, special or consequential which the purchaser

may experience as a result of the installation or use of the product. The buyer's sole remedy for

any breach of this agreement by Geokon, Inc. or any breach of any warranty by Geokon, Inc.

shall not exceed the purchase price paid by the purchaser to Geokon, Inc. for the unit or units,

or equipment directly affected by such breach. Under no circumstances will Geokon reimburse

the claimant for loss incurred in removing and/or reinstalling equipment.

Every precaution for accuracy has been taken in the preparation of manuals and/or software,

however, Geokon, Inc. neither assumes responsibility for any omissions or errors that may

appear nor assumes liability for any damages or losses that result from the use of the products

in accordance with the information contained in the manual or software.

TABLE of CONTENTS

Page

1. INTRODUCTION ..................................................................................................................................................1

BASIC CIRCUIT: .......................................................................................................................................................1

2. THEORY OF OPERATION .................................................................................................................................3

3. INSTALLATION....................................................................................................................................................4 3.1 PROTECTING THE TRANSDUCER ..........................................................................................................................4 3.2 PROTECTING THE DATALOGGER ..........................................................................................................................5 3.4 ESTABLISHING AN EARTH GROUND. ....................................................................................................................5

3.4.1 Ground Rods...............................................................................................................................................6 3.4.2 Measuring the Resistance of the Grounding System..................................................................................6

4. COMPONENT SPECIFICATIONS .....................................................................................................................7

TABLES and FIGURES

FIGURE 1: LAB-3 SCHEMATIC........................................................................................................................................1 PHOTO OF THE LAB-3 LIGHTNING PROTECTION ............................................................................................................2 FIGURE 2: LAB-3 LIGHTNING TRANSIENT PROTECTION ................................................................................................3 FIGURE 3: LAB-3 CIRCUIT BOARD.................................................................................................................................4 TABLE 1: LAB-3 CIRCUIT BOARD WIRING.....................................................................................................................4 FIGURE 4: SUGGESTED SETUP FOR MEASURING THE SOIL RESISTANCE OF A GROUND ROD..............................................6

1 1. INTRODUCTION The Geokon, Inc. Model 4999-12L Surge Protection Board (LAB-3) is designed to protect Geokon vibrating wire transducers and 5V signals (-A option), 12V power and signals (-B option) and 24V power and signals (-C option) when used in conjunction with multiplexers and dataloggers, from short-duration high-voltage surges that may be induced in the transducer electrical cables by lightning strikes in the vicinity. They are designed for installation in the cable leading from the transducer to the datalogger, or in the datalogger itself. The LAB-3 is normally supplied inside a water-tight Nema 4 Enclosure (4999-12-LE). Disclaimer. Please Note that nothing can protect a system from a direct lightning strike nor one so close that it swamps the capacity of the LAB-3 Board. Nor is it possible to state how far away the lightning strike must be to prevent sparking across the protective devices. Therefore use of the LAB-3 device is no guarantee that damage will not occur in the event of a strike! Geokon, Inc. is not responsible for any damage or loss suffered in that event. Basic Circuit:

Figure 1: LAB-3 Schematic

2

Photo of the LAB-3 Lightning Protection

32. THEORY OF OPERATION

The primary protection is a tripolar gas tube protection device. This device limits the energy to the protected circuit by switching, in a few nanoseconds, from a high impedance state to a low impedance state in the presence of a sufficiently high transient voltage. It is comprised of three electrodes separated by a fixed distance in a hermetically-sealed, gas-filled chamber. The outer electrodes are connected to the two leads of the circuit to be protected, and the center electrode is connected to an earth ground. When transient voltages exceed the devices rated breakdown voltage, (dependent on electrode spacing, inert gas type, gas pressure, and rise time of the transient, in the present case a nominal 230 volts), it begins arcing or conducting, thereby diverting the potentially damaging energy away from the protected circuit and towards the earth ground.

While conducting, the voltage drop or arc voltage across the gas tube is quite low (typically less than 20 volts), hence the majority of the transient is dissipated in the earth ground, not in the gas tube itself or the protected circuit. When the transient has passed, the device returns to its former high impedance state. The plots below illustrate energy content versus time of a lightning strike at various points in the lightning protection circuit. The initial pulse enters the lightning board at either the SA1 or SA2 side and presents itself to the primary stage protection component (SA1 or SA2). This tripolar plasma surge arrestor, (rated at 10 kA), will begin shunting the energy to ground when the nominal breakdown voltage, (230 V) is exceeded. (Typically 184-276 volts). The inductors L1 and L2 (or L3 and L4) delay the 230 volt pulse to the secondary stage protection to allow sufficient time for the breakdown voltage of the transzorbs to be exceeded and therefore to actuate. The transzorbs, TZ2 and TZ3,(rated at 1500 Watts), clamp the common mode voltage to a nominal 6 volts (LAB-3A), 16 volts(LAB-3B) or 30 volts(LAB-3C). The transzorb TZ1, (rated at 1500 Watts), completes the secondary stage protection by clamping the normal mode voltage to 6 volts(LAB-3A), 16 volts(LAB-3B) or 30 volts(LAB-3C).

T

E

T

E

T

E

Initial Pulse Primary Stage Secondary Stage

Figure 2: LAB-3 Lightning Transient Protection The shield is protected by a plasma surge arrestor rated at 20kA surge absorption with a 300 volt breakdown.

4 3. INSTALLATION 3.1 Protecting the Transducer For protection of the transducer it is recommended that the LAB-3 (LAB-3A) Board be installed as close to the transducer as is practicable. For piezometers installed in boreholes, this usually means installation at the top of the borehole where the cable comes out of the ground and the LAB-3 Board is accessible. Transducer leads are pushed through the spiral strain relief (supplied) and then through the connector on either the TB1 or TB2 end of the LAB-3 Enclosure. The leads are then connected to either the TB1 or TB2 terminal block. Connect the transducer wires as shown in the table below. The shield wire (no insulation) must be connected to the shield terminal (5). After the connections have been made, tighten the spiral strain relief onto the cable and connector and then bolt down the lid to the enclosure.

Figure 3: LAB-3 Circuit Board

TB1/TB2 POSITION SIGNAL WIRE COLOR 1 VW+ RED 2 VW- BLACK 3 TH+ WHITE 4 TH- GREEN 5 SHIELD SHIELD E EARTH -

Table 1: LAB-3 Circuit Board Wiring

5 In order for the LAB-3 board to be effective it is essential that it be located as close as practically possible to the protected device and that a proper earth ground be established. (See section 3.4). The preferred way to achieve solid earth ground is to solder a length of ¼” tinned copper wire braid from the EARTH solder pad (located on the back side of the LAB-3 circuit board adjacent to TB-1) to a ground lug on the side of the LAB-3 enclosure. All model 4999-12-LE (in NEMA 4 Enclosure) LAB-3 devices manufactured at Geokon have the external Earth Ground lug connected to the circuit board in this fashion. Alternatively (but not recommended), earth ground connection may be made via the (2) E terminals on TB1 and TB2 or via the circuit board mounting holes. When the board is mounted to a grounded metal enclosure, electrical continuity is made from the mounting holes to the board via the stand-offs. It may be necessary to scrape off some of the paint to get a low resistance value. An earth ground can then be made through the bolts holding the enclosure. Connection to earth ground can then be completed by running a wire (at least 14 AWG) from the ground lug on the side of the enclosure to a known, or constructed earth ground (either a ground stake or local electrical system ground. See section 3.4 for more details). 3.2 Protecting the Datalogger In the event that the LAB 3 Board is used to protect a multiplexer or a datalogger, locate the LAB-3 board as close to the multiplexer or datalogger as possible.

3.3 Protecting Ancillary Equipment The LAB-3 board is a 2-circuit protection device, with TB1/TB2 pins 1 & 2 provided for the first circuit to be protected, and TB1/TB2 pins 3 & 4 provided for the second circuit to be protected. The LAB-3 is also provided in 3 configurations:

5V signals (-A option) 12V power and signals (-B option) 24V power and signals (-C option)

Typical signals and systems that can be protected include CMOS and TTL logic (5V), Power supplies (12V and 24V) and 4-20mA current loops (24V). 3.4 Establishing an Earth Ground. A poor grounding system will render the whole system useless. The lightning needs to see a high impedance through the transducer and a low impedance to earth ground. The resistance to ground must be 20 ohms or less. So the main objective is to get as low a resistance as possible. In order to achieve this there are four variables to consider: the use of a sufficient number of ground rods, placement in the right soils, sufficient depth and soil conductivity enhancement.

6 3.4.1 Ground Rods When choosing a ground rod use only the better quality types available in electrical supply houses – the ones with thick copper plating. If these are not available a ½ inch diameter copper pipe will suffice. The length should be at least 2 meters. More than one rod can be connected in parallel. Rods connected in parallel should be spaced at least 6 ft apart. Connection of the ground wire to the ground rod is best done with silver solder. If clamps are used they may corrode requiring frequent inspection to see that they remain in good condition. No loops should be permitted in the ground wires. The soil in which the ground rod is driven may not be soft enough to allow deep penetration in which case multiple rods may be necessary. As an alternative to rods, buried mats of wire mesh have been used. Soil conductivity can be enhanced by charging the soil around the ground rod with a pound or so of rock salt or magnesium sulfate. Sandy soils have the highest resistance and may require these special enhancement measures. Be aware that frozen ground has a much higher resistance, (up to eight times higher), than unfrozen ground so that ground rods should be driven at least half to one meter below the frost line. 3.4.2 Measuring the Resistance of the Grounding System In order to measure the ground resistance the following method is suggested. If a VOM is used it is necessary to take into account the AC component from ground currents and the DC component from electrolytic action. This mandates the use of two additional ground rods spaced 6 meters apart. Refer to the figure below for the following.

Figure 4: Suggested setup for measuring the soil resistance of a ground rod

First measure and record the resistance between rods X and Y. Reverse the meter leads and again record the reading. Calculate the average of the two readings and call it (XY). Repeat this procedure between rods X and Z and between rods Y and Z then calculate the resistance to ground of rod X, the ground rod under test, from the formula.

Ground Rod Resistance = (XY) + (XZ) – (YZ)

20’ 20’

20’

VOM

X

Y Z

Ground Rod Under Test

74. COMPONENT SPECIFICATIONS 4999-12-A TRANSIENT VOLTAGE SUPRESSOR: Diodes Inc. SMCJ6.0CA-13 6.0V 1500W Bi-directional 4999-12-B TRANSIENT VOLTAGE SUPRESSOR: Diodes Inc. SMCJ16CA-13 16V 1500W Bi-directional 4999-12-C TRANSIENT VOLTAGE SUPRESSOR: Diodes Inc. SMCJ30CA-13 30V 1500W Bi-directional 4999-12-A,B,C TRIPOLAR PLASMA SURGE ARRESTOR: Citel BTR-230 230V Breakdown Voltage 10kA current capability BIPOLAR PLASMA SURGE ARRESTOR: CP CLARE CG2-300L 300V Breakdown Voltage 20kA current capability 10uH INDUCTOR: Sumida CDRH125-100MC

10uH 4A