D20

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2502 Series Level-Trol � ControllerContents

Introduction 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scope of Manual 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Description 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Specifications 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Controller Action 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Installation%2249 Series Sensors 2. . . . . . . . . . . . . . . . . . . . . . . . . . Uncrating 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Controller Orientation 4. . . . . . . . . . . . . . . . . . . . . . . . . Mounting Caged Sensors 4. . . . . . . . . . . . . . . . . . . . . Mounting Cageless Sensors 5. . . . . . . . . . . . . . . . . . .

Side-Mounted Sensor 7. . . . . . . . . . . . . . . . . . . . . . . Top-Mounted Sensor 7. . . . . . . . . . . . . . . . . . . . . . . .

Special Constructions 7. . . . . . . . . . . . . . . . . . . . . . . . Temperature-Compensated Displacer 7. . . . . . . . . Piezometer Ring 8. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Regulator Supply Pressure 8. . . . . . . . . . . . . . . . . . . .

Prestartup Checks 9. . . . . . . . . . . . . . . . . . . . . . . Adjustments 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Level Set Adjustment 10. . . . . . . . . . . . . . . . . . . . . . Proportional Band Adjustment 10. . . . . . . . . . . . . . Reset Adjustment 10. . . . . . . . . . . . . . . . . . . . . . . . . Differential Relief Adjustment 10. . . . . . . . . . . . . . .

Calibration 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Precalibration Requirements 11. . . . . . . . . . . . . . . . .

Wet Calibration 11. . . . . . . . . . . . . . . . . . . . . . . . . . . Dry Calibration 11. . . . . . . . . . . . . . . . . . . . . . . . . . . Controller and Torque Tube Arm Disassembly 11Determining Suspended Weight for Calibration 12

Calibration Procedure 12. . . . . . . . . . . . . . . . . . . . . .

Startup 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Principle of Operation 13. . . . . . . . . . . . . . . . . . Type 2502 Controller 15. . . . . . . . . . . . . . . . . . . . . . . Type 2502F Controller with Reset Relief Valve 15.

Figure 1. Type 2502 Controller Mounted onType 249B Sensor

W3121-3/IL

TYPE 249B SENSOR

TYPE 2502 CONTROLLER

Maintenance 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Troubleshooting 16. . . . . . . . . . . . . . . . . . . . . . . . . . . Removing Controller from Sensor 16. . . . . . . . . . . . Changing Mounting Method 18. . . . . . . . . . . . . . . . . Installing Controller on Sensor 19. . . . . . . . . . . . . . . Changing Proportional, Reset, or

Differential Relief Valve 19. . . . . . . . . . . . . . . . . . . . Testing Relay Dead Band 19. . . . . . . . . . . . . . . . . . . Changing Relay 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . Replacing Bellows 20. . . . . . . . . . . . . . . . . . . . . . . . . Reversing Action 20. . . . . . . . . . . . . . . . . . . . . . . . . . . Disassembling Relay 20. . . . . . . . . . . . . . . . . . . . . . .

Parts Ordering 21. . . . . . . . . . . . . . . . . . . . . . . . . . .

Parts Kits 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Parts List 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Instruction ManualForm 1446June 1994 2502 Series

2502 Series

2

Introduction

Scope of ManualThis instruction manual provides installation, operat-ing, calibration, maintenance procedures for 2502 Se-ries pneumatic controllers (figure 1) used in combina-tion with 249 Series level sensors.

This manual does not include regulator or sensorinstallation or maintenance procedures. For this infor-mation, refer to the instruction manual for the appropri-ate regulator and 249 Series level sensor.

Only personnel qualified through training or experienceshould install, operate, and maintain this controller. Ifthere are any questions concerning these instructionscontact your Fisher Controls sales office or sales rep-resentative before proceeding.

DescriptionThe Type 2502 Level-Trol� Controller described inthis manual provides proportional-plus-reset and pro-portional-plus-reset-with-anti-reset-windup control. Thecontroller output is a pneumatic signal that operates afinal control element. These controllers are designedto control liquid level, the level of interface betweentwo liquids, or density (specific gravity). Each unit con-sists of a 249 Series liquid level sensor and a 2502Series pneumatic controller.

Refer to the Principle of Operation section for a morecomprehensive discussion of how the Type 2502pneumatic controller operates.

SpecificationsTable 1 gives general specifications for the Type 2502Series Controllers.

Controller-Sensor ActionThe following controller description is for right-handmounting. Left-hand mounting produces an output sig-nal with the opposite action. Figure 4 shows cagehead mounting positions.

For right-hand mounting:� Direct Action--Increasing liquid or interface level, ordensity, increases the output signal.

� Reverse Action--Decreasing liquid or interface level,or density, increases the output signal. A factory-sup-

Figure 2. Guidelines for Use of Optional Heat Insulator Assembly

USE INSULATOR (CAUTION! IF AMBIENT DEWPOINT ISABOVE PROCESS TEMPERATURE, ICE FORMATION MAYCAUSE INSTRUMENT MALFUNCTION AND REDUCEINSULATOR EFFECTIVENESS.)

0 20 40 60 80 100 120 140 160

0 10 20–18 –10 30 40 50 60 7071

593

500

400

300

200

100

00

400

800

1100

–20 –29

NO INSULATOR NECESSARY

AMBIENT TEMPERATURE (�C)

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AMBIENT TEMPERATURE (�F)

HEAT INSULATORREQUIRED

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NOTE: FOR SERVICE BELOW –20 �F (–29�C) CONTACT FACTORY.

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0 20 40 60 80 100 120 140 200

0 10 20–18 –10 30 40 50 60 7093

593

500

400

300

200

100

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400

800

1100

–20 –29

NO INSULATOR NECESSARY

AMBIENT TEMPERATURE (�C)

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AMBIENT TEMPERATURE (�F)

HEAT INSULATORREQUIRED

TOOHOT

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180160

80 90

USE INSULATOR (CAUTION! IF AMBIENT DEWPOINT ISABOVE PROCESS TEMPERATURE, ICE FORMATION MAYCAUSE INSTRUMENT MALFUNCTION AND REDUCEINSULATOR EFFECTIVENESS.)

plied reverse-acting unit has the suffix letter R addedto the type number.

InstallationThe 2502 Series controllers are used in combinationwith 249 Series sensors, and unless ordered separate-ly, the controller will be attached to the sensor.

249 Series Sensors� The Type 249, 249B, 249C, 249K, 249L, and

249N, sensors side-mount on the vessel with the dis-placer mounted inside a cage (caged) outside the ves-sel.

� The Type 249BP and 249CP sensors top-mounton the vessel with the displacer hanging down into thevessel (cageless).

� The Type 249V sensor side-mounts on the ves-sel with the displacer hanging out into the vessel(cageless).

External sensors provide more stable operation thando internal sensors for vessels with internal obstruc-tions or considerable internal turbulence.

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Table 1. Specifications

Available Configurations

Type 2502: A direct-acting controller which pro-vides proportional-plus-reset controlType 2502C: A Type 2502 with a level indicatorassemblyType 2502F: A Type 2502 with a differential reliefvalveThese type numbered products are also avail-able with reverse action. For example, Type2502R, Type 2502CR, and 2502FR

Input Signal (1)

Liquid Level or Liquid-to-Liquid Interface Level:From 0 to 100 percent of displacer length—stan-dard lengths for all sensors are 14 inches (356 mm)or 32 inches (813 mm). Other lengths available de-pending on sensor constructionLiquid Density: From 0 to 100 percent of displace-ment force change obtained with given displacervolume—standard volumes are 60 inches3 (980cm3) for Types 249C and 249CP sensors, or 100inches3 (1640 cm3) for most other 249 Series sen-sors; other volumes available depending onconstruction

Output Signal (1)

3 to 15 psig (0.2 to 1.0 bar) or 6 to 30 psig (0.4 to2.0 bar)Action: Field reversible between direct (increasingliquid or interface leel or specific gravity increasesoutput pressure) and reverse (increasing liquid orinterface level or specific gravity decreases outputpressure)

Area Ratio of Relay Diaphragms

3:1

Supply Pressure Requirement

20(2) psig (1.4 bar) for 3 to 15 psig (0.2 to 1.0 bar)output signal or 35(2) psig (2.4 bar) for 6 to 30 psig(0.4 to 2.0 bar) output signal

Maximum Supply Pressure

50 psig (3.4 bar)

Supply Pressure Consumption

At 20 Psig (1.4 bar)Minimum: 4.2 scfh(3) (0.11 m3/h) at proportional

band setting of 0 or 200 percentMaximum: 27 scfh (0.72 m3/h) at proportional bandsetting of 100 percentAt 35 psig (2.4 bar)Minimum: 7 scfh (0.2 m3/h) at proportional bandsetting of 0 or 200 percentMaximum: 42 scfh (1.1 m3/h) at proportional bandsetting of 100 percent

Performance

Hysteresis: 0.6 percent of output pressure changeat 100 percent of proportional bandRepeatability(1): 0.2 percent of displacer length ordisplacement force changeDead Band(1): 0.05 percent of proportional band orspanTypical Frequency Response (1): 4 Hz and 90-de-gree phase shift at 100 percent of proportional bandwith output piped to typical instrument bellows using20 feet (6.1 meters) of 1/4 inch (6.4 mm) tubingAmbient Temperature Error: �1.5 percent of out-put pressure change per 50�F (28�C) of tempera-ture change at 100 percent of proportional bandwhen using sensor with standard-wall N05500(K-Monel(4)) torque tube with 249 Series sensorsReset(1): Adjustable from 0.01 to 74 minutes perrepeat (100 to 0.01 repeats per minute)Differential Relief (Type 2502F and 2502FR Con-trollers Only): Adjustable from 2 to 7 psi (0.1 to0.48 bar differential) to relieve excessive differencebetween proportional and reset pressures. Differen-tial relief can be switched between rising outputpressure and falling output pressure.

Standard Tubing Connections

1/4 inch (6.4 mm) NPT female

Maximum Working Pressures (Sensors Only)

Consistent with aplicable ANSI pressure/tempera-ture ratings

Operative Ambient Temperatures

Standard Construction: �40 to 160�F (�40 to71�C)High Temperature Construction: 0 to 220�F(�18 to 104�C). See figure 2

1. Term defined in ISA Standard S51.1-1979.2. Control and stability may be impaired if this pressure is exceeded.3. Scfh=standard cubic feet per hour at 60�F and 14.7 psia (normal cubic meters per hour (m3/hr) at 0�C and 1.01325 bar).4. K-Monel is a mark owned by Inco International.

2502 Series

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WARNING

When replacing the sensor assembly,the displacer may retain process liquidor pressure. Personal injury or propertydamage due to sudden release of pres-sure, contact with hazardous liquid, fire,or explosion can be caused by punctur-ing, heating, or repairing a displacerthat is retaining process pressure or liq-uid. This danger may not be readily ap-parent when disassembling the sensoror removing the displacer. Before disas-sembling the sensor or removing thedisplacer, observe the more specificwarning provided in the sensor instruc-tion manual.

UncratingUnless ordered separately, the controller will be at-tached to the sensor when shipped. Carefully uncratethe assembly.

CAUTION

A thin-wall torque tube has a T stampedon the sensor end flange (not visible un-less the controller/transmitter is re-moved from the sensor). For sensorswith a thin-wall torque tube, always sup-port the displacer if the travel stop mustbe removed.

Note

Caged sensors have a rod and blockinstalled on each end of the displacer toprotect the displacer in shipping. Re-move these parts before installing thesensor to allow the displacer to functionproperly.

Caged sensors will be shipped with the displacerinstalled in the cage. If the sensor is ordered with atubular gauge glass, the gauge glass will be cratedseparately and must be installed at the site. Be certainthat the cage equalizing connections are not pluggedwith foreign material.

A caged sensor has a damping plate installed in thelower screwed or flanged connection to provide morestable operation. If the process liquid could clog theplate opening with sediment, then remove the damp-ing plate. For screwed connections, use a 1/2-inch

Figure 3. Pressure Connections

1/4”-18 NPTSUPPLYCONNECTION

ADJUSTINGSCREW

FILTER WELL

DRAIN VALVE

LOCKNUT

1/4”-18 NPTOUTPUTCONNECTION

VENT

PRESSUREREGULATOR

CD1700-EA1909-1/IL

(12.7 mm) hexagon wrench to unscrew the dampingplate. For flanged connections, use a screwdriver topry the damping plate out of the flange.

A cageless sensor is shipped with the displacer sepa-rated from the sensor assembly. A displacer longerthan 32 inches (813 mm) is crated separately. A short-er displacer is crated with the sensor, but is not at-tached to the displacer rod. Inspect the displacer andreplace if it is dented. A dent may reduce the pressurerating of the displacer.

Controller OrientationA controller is to be mounted with the vent openingpointing downward as shown in figure 3. This orienta-tion is necessary to ensure draining of accumulatedmoisture. The controller is attached to the sensor inone or the other of the mounting positions shown infigure 4: Right hand (with the case to the right of thedisplacer when looking at the front of the case) or lefthand (with the case to the left of the displacer). Themounting position can be changed in the field if re-quired; refer to the appropriate sensor manual for in-structions. Changing this mounting position will changecontroller action from direct to reverse, or vice versa.

All caged sensors have a rotatable head. That is, thecontroller may be positioned at any of eight alternatepositions around the cage as indicated by the numbers1 through 8 in figure 4. To rotate the head, remove thehead flange bolts and nuts and position the head asdesired.

Mounting Caged Sensor

CAUTION

The cage must be installed plumb sothat the displacer does not touch thecage wall. Should the displacer touchthe cage wall, the unit transmits an erro-neous output signal.

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Figure 4. Cage Head Mounting Positions Figure 5. Cage Connection Styles

A1271–2/ILAH9150–AA2613–2/IL

Note

If the controller is not mounted on thesensor, refer to the Installing Controlleron Sensor section. That section alsoprovides instructions for adding a heatinsulator to a unit. If a temperature-com-pensating displacer or piezometer ringis used, refer to the special installationprocedures in this section before pro-ceeding.

Cage connections will normally be either 1-1/2 or2-inch (38.1 to 50.8 mm) screwed or flanged. Figure 5shows the combinations. It is recommended that adrain be installed between the cage and shutoff orhand valve whenever the bottom cage line has a liq-uid-trapping low point.

Mount the cage by running equalizing lines betweenthe cage connections and the vessel (figure 6). Onliquid or interface level applications, position the sen-sor so that the line marked FLOAT CENTER on thecage is located as close as possible to the center ofthe liquid level or interface level range being mea-sured.

For liquid or interface level applications, it is advanta-geous to install a gauge glass either on the vessel, oron the sensor cage (if the cage is tapped for a gauge).With flanged connections, use standard gaskets orother flat-sheet gaskets compatible with the processliquid. Spiral wound gaskets without compression-con-trolling centering rings cannot be used for flanged con-nections.

Mounting Cageless Sensor

CAUTION

If a stillwell is used, it must be installedplumb so that the displacer does nottouch the wall of the stillwell. Shouldthe displacer touch the wall while theunit is in service, the unit will transmitan erroneous output signal.

Since the displacer hangs inside the vessel, it is advis-able to provide a stillwell around the displacer whenthe liquid is in a state of continuous agitation and ex-cessive turbulence can be expected.

2502 Series

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Figure 6. Caged Sensor Mounting

DRAIN

CENTER OFLIQUID OR INTERFACELEVEL

DF5379-AA6771/IL

SHUTOFFVALVES

VENT

EQUALIZINGLINE

CAUTION

Since a displacer used in an interfacelevel or a density application must becompletely submerged during opera-tion, obtaining desired controller sensi-tivity requires the use of either a thin-wall torque tube or an overweightdisplacer, or both. An overweight dis-placer cannot be used for any serviceexcept those conditions for which it wasspecified.

Note

If the controller is not mounted on thesensor, refer to the Installing Controlleron Sensor section. That section alsoprovides instructions for adding a heatinsulator to a unit. If the sensor has atemperature-compensated displacer orpiezometer ring, refer to the specialconstructions procedures in this sec-tion before proceeding.

Attach a cageless sensor to a flanged connection onthe vessel as shown in figure 7. For interface or liquidlevel applications, install a gauge glass on the vessel.

Figure 7. Cageless Sensor Mounting

CF5380-AA3893/IL

TOPMOUNTED

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CAUTION

If the displacer is to be inserted into thevessel before being attached to the dis-placer rod, provide a suitable means of

2502 Series

7

supporting the displacer to prevent itfrom dropping into the vessel and suf-fering damage.

To help support a Type 249BP or 249CP displacer,install the displacer stem and stem end piece, or athreaded rod, into the 1/4 inch-28 UNF threaded holein the displacer spud or stem end piece (figure 8). Onthe Type 249BP with optional travel stop, the stemend piece pins will secure the displacer as long as thetravel stop plate is installed and the sensor head is inposition.

Side-Mounted SensorIf a stillwell is required (figure 7), the displacer must beattached to the displacer rod from inside the vessel.Connect the displacer as shown in figure 8, locking theassembly with the cotter spring provided. If a stillwellis not required, the displacer can be attached to thedisplacer rod before mounting the sensor to the vesselconnection. The displacer may then be swung out hor-izontally for insertion into the vessel. If an extension isused between the displacer spud and the displacerstem end piece, make sure the nuts are tight at eachend of the displacer stem extension. Install and tightensuitable bolting or cap screws in the flanged connec-tion to complete the installation.

Top-Mounted SensorFigure 7 shows the installation of a top-mounted cage-less sensor. The displacer may be attached to the dis-placer rod before installing the sensor on the vessel.Where the displacer diameter is small enough, it maybe desirable to install a long or sectionalized displacerthrough the sensor head access hole after the sensoris installed on the vessel. Connect the displacer asshown in figure 8, locking the assembly with the cottersprings provided. If a stem is used between the dis-placer as shown in figure 8, lock the assembly with thecotter springs provided. If a stem is used between thedisplacer spud and the stem end piece, make sure thenuts are tight at each end of the stem. Install and tight-en suitable cap screws in the flanged connection tocomplete the installation.

Special Constructions

Temperature-Compensated DisplacerSome sensors use a temperature-compensated dis-placer (figure 9). This displacer is appropriate for den-sity applications that do not tolerate specific gravitychanges due to temperature. The displacer must befilled with the liquid to be measured, or with a liquid ofequal expansion coefficient. In service, the displacer

W0228-1A/IL

DISPLACER ROD

DISPLACERSPUD

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COTTER SPRING

Figure 8. Displacer/Displacer Rod Connections

W0229-1A/IL

COTTER SPRING

DISPLACER ROD

LOCKING NUTS

DISPLACER SPUD

DISPLACERSTEMEXTENSION

DISPLACERSTEMEND PIECE

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A0746–1/IL

Figure 9. Temperature-Compensated Displacer

2502 Series

8

expands and contracts the same amount as the mea-sured liquid to nullify signal changes that would becaused by temperature changes.

This type of displacer is shipped in a separate cartonbut crated with the rest of the assembly. See the ap-propriate sensor manual for filling instructions.

Piezometer RingA piezometer ring (figure 10) is used when it is desir-able to measure the specific gravity of a liquid in aflowing line, and when the liquid velocity exceeds twofeet/minute (10 mm/second) past the displacer in thecage. The piezometer ring reduces the velocity effectscaused by liquid passing through the displacer cage.

To install this type of sensor, connect a line to thecage inlet and outlet piping at each end of the cage.Use hand valves to balance the liquid flow through thecage and keep the displacer cage filled. It is advisableto provide a rotameter or sight flow gauge for measur-ing velocity through the cage. If the flow rates areproperly balanced, the transmitter output will showlittle change when flow through the cage is shut off. Ifthe flow rate through the cage is too high the turbu-lence may cause an erratic output pressure signal.Readjust hand valves to stabilize the output pressuresignal.

Regulator Supply Pressure

WARNING

Do not overpressurize any system com-ponent. Personal injury or propertydamage may occur due to sudden pres-sure release or explosion. To avoiddamage, provide suitable pressure-re-lieving or pressure limiting devices ifsupply pressure can exceed the maxi-mum supply pressure listed in table 1.

Personal injury or property danage mayoccur from an uncontrolled process ifthe supply medium is not clean, dry, oil-free, or non-corrosive gas. Industry in-strument air quality standards describeacceptable dirt, oil, and moisture con-tent. Due to the variability in nature ofthe problems these influences can haveon pneumatic equipment, Fisher Con-trols has no technical basis to recom-mend the level of filtration equipmentrequired to prevent performance degra-dation of pneumatic equipment. A filteror filter regulator capable of removing

Figure 10. Piezometer-Ring Cage for Flow Line Mounting

A1317-1/IL

particles 40 microns in diameter will suf-fice for most applications. Use of suit-able filtration equipment and the estab-lishment of a maintenance cycle tomonitor its operation is recommended.

Standard 2502 Series controllers come complete withsupply and output pressure gauges and an integrallymounted Type 67FR regulator to reduce supply pres-sure from a maximum of 250 psig (17.3 bar) to the 20or 35 psig (1.4 or 2.4 bar) required. This regulator hasbuilt-in relief and a standard 40-micron to remove par-ticles from the supply source.

The output pressure connection is on the back of thecontroller case (figure 3). Pipe the supply pressure tothe in connection of the regulator mounted to the caseback. Provide a clean, dry, and noncorrosive air or gassupply to the controller as follows:

After pressure connections have been made, turn onthe supply pressure and check all connections forleaks.

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Figure 11. Controller Adjustments

RESET ADJUSTMENT

W5637/IL/A

29A2834-C

30A8943-HA1933/IL

1E8731-C1E8732-CA1897-1/IL

21A6447-AA1903/IL

Prestartup Checks

WARNING

The following calibration procedure re-quires taking the controller out of ser-vice. To avoid personal injury and prop-erty damage caused by an uncontrolledprocess, provide some temporarymeans of control for the process beforetaking the controller out of service.

Adjustment locations are shown in figure 11 unlessotherwise indicted. When performing the checks, openloop conditions must exist. One way to obtain an openloop is to ensure that there is no flow through the finalcontrol element. Another way to obtain an open loop isto disconnect the controller output signal line and plugthe output connection.

During startup, it is necessary to change process lev-els to position the displacer from its maximum to itsminimum range of operations. Provide a means tochange the process level or interface. If the processvariable cannot be varied sufficiently, follow the in-

2502 Series

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structions in the Calibration section to simulate theprocess variable changes required for these checks.

Make sure that the raise level dial on the controller ismounted with the correct side facing out. The dial isprinted on both sides with the arrow on one side point-ing to the left and the arrow on the other side pointingto the right. Figure 11 shows the dial arrow positionedfor a sensor that is mounted to the left of the control-ler; the arrow points to the left. If the sensor is to theright of the controller, remove the two mountingscrews, turn the dial over so the arrow points to theright, then reinstall the mounting screws.

On a controller with optical mechanical indicator as-sembly, the travel indicator plate is printed on bothsides. If the sensor is to the left of the controller (right-hand mounting), use the side of the plate that has thearrow pointing to the left. If displacer is to right of con-troller (left-hand mounting), use the side of the platethat has the arrow pointing to the right.

1. Turn on the supply pressure and check that thecontroller supply gauge reads 20 psig (1.4 bar) for a 3to 15 psig (0.2 to 1.0 bar) output pressure range or 35psig (2.4 bar) for a 6 to 30 psig (0.4 to 2.0 bar) outputpressure range. If the pressure is incorrect, loosen thelocknut of the filter/regulator (figure 3); turn the adjust-ing screw clockwise to increase or counterclockwise todecrease pressure. Tighten the locknut after settingthe pressure.

2. Turn the reset control to .05 minutes per repeat.

3. Locate the process variable at its minimum value(on level applications, for instance, lower the liquidbelow the displacer). Zero the proportional band andraise level controls. Output pressure on direct-actingcontrollers should be greater than zero but less than 3psig (0.2 bar) for the 3 to 15 psig (0.2 to 1.0 bar) rangeor 6 psig (0.4 bar) for the 6 to 30 psig (0.4 to 2.0 bar)range. For reverse-acting controllers, the output pres-sure should be greater than 15 psig (1.0 bar) and lessthan 20 psig (1.4 bar) for the 3 to 15 psig (0.2 to 1.0bar) range or greater than 30 psig (2.0 bar) and lessthan 35 psig (3.4 bar) for the 6 to 30 psig (0.4 to 2.0bar) range. On a controller with indicator assembly,the pointer should be over the low point on the indica-tor plate; slight adjustment might be necessary byloosening the bottom shaft nut (key 40, figure 16),shifting the pointer, and retightening the nut.

4. Set the raise level control as desired. Determinethe dial setting by moving the nameplate slide until thespecific gravity on scale B is opposite the displacervolume on scale A. Choose the percentage of displac-er length, as measured from the displacer bottom, thatyou desire the liquid or interface level to cover. Locatethis percentage on scale D, and read up from this per-centage to find the raise level dial setting on scale C.For example, with a liquid level application, a specific

gravity of one (water service), and a 90-cubic-inch (1.5L) displacer, move the slide so that 1.0 on scale B isover 90 on scale A. If it is desired to have water levelcover 50 per cent of the displacer length at the controlpoint, read up from 50 on scale D to find a 4.5 dial set-ting on scale C.

5. Relocate the process variable to the control pointdetermined in step 4. If not, see if another setting onthe raise level dial brings the output pressure intoagreement with the process. For example, with waterlevel at 50 percent of the height of the displacer, theoutput of a 3-15 psig (0.2 to 1.0 bar) unit should beaproximately 50 percent of the way between 3 and 15psig (0.2 and 1.0 bar) or 9 psig (0.6 bar). If the newsetting is more than one graduation away from thesetting determined in step 4, the unit would appear tobe out of calibration and recalibration may be desir-able. See Calibribration Procedure on page 12 steps 1thru 10.

On a controller with level indicator, the pointer shouldreflect the magnitude of the process variable; forinstance, with liquid or interface level covering 50 per-cent of the displacer, the pointer should be in themiddle of the high-low scale. Slight plate adjustmentmight be necessary as described at the end of step 3.

6. If all prestartup checks are satisfactory proceed tothe Startup section.

AdjustmentsController adjustments are provided in this section.Refer to figure 11 for adjustment locations.

Level Set AdjustmentTo perform the level adjustment, open the controllercover, loosen the knurled adjustment screw (see figure11), and rotate the adjustment lever around the RAISELEVEL dial. To raise the fluid or interface level, or in-crease density, rotate this knob in the direction of thearrows. To lower the level or decrease density, rotatethe knob in the opposite direction. This procedure isthe same for both direct and reverse action controllers.Tighten the knurled screw.

Note

The raise level dial does not reflect actu-al fluid level in the tank or fluid levelposition on the displacer.

Proportional Band AdjustmentProportional band adjustment is made to change theamount of displacement force change required to ob-tain full output pressure change, by determining the

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percentage of pressure fed back to the proportionalbellows. The adjustment is performed by opening thecontroller cover and turning the percent proportionalband knob (just below the raise level dial).

Reset AdjustmentTo adjust reset action (figure 11) turn the knob clock-wise to decrease the minutes per repeat. Turn theknob counterclockwise to increase the minutes perrepeat. Increasing the minutes per repeat provides aslower reset action.

The reset rate adjustment dial is calibrated in minutesper repeat. By definition, this is the time in minutesrequired for the reset action to produce a correctionwhich is equal to the correction produced by propor-tional control action. This is, in effect, the time in min-utes required for the controller to increase (or de-crease) its output pressure by an amount equal to aproportional increase (or decrease) caused by achange in control conditions.

Differential Relief AdjustmentThe differential relief valve protrudes from the back ofthe controller case on a construction with an F in thetype number. Although normally factory-set to relievewhen the differential between the proportional and re-set bellows reaches 5 psi, the differential may be re-duced down to 2 psi by turning the adjustment screwclockwise or increased up to 7 psi by turning the screwcounterclockwise. The minimum differential setting willyield the minimum set point overshoot during startup.

Depending on the characteristics of the process, therelief valve can be positioned so that the arrow cast onthe case points either to the letters RE (reset) or to theletter P (proportional) on the back of the manifold. Toreposition the arrow, see figure 11. Remove themounting screws. Reposition the differential reliefvalve to RE or P and reinstall the mounting screws.

Calibration

Precalibration Requirements

Note

Calibration of a unit with a displacer de-signed for interface or density controlmust be conducted with the displacercompletely submerged in a liquid of thespecific gravity for which the unit wasdesigned.

To calibrate a controller, it is necessary to place thedevice into operation. This may be done on the vesselwith the actual service liquid. It may also be done inthe shop, but other means of obtaining a displacementforce change must be provided. It must be done in theshop if the process variable is not available for calibra-tion or if the process cannot be varied for calibration.There are two methods of adapting the calibration pro-cedure to shop calibration: wet and dry.

Wet CalibrationRemove the entire controller and sensor assemblyfrom the vessel. For caged sensors, pour the liquidinto the cage. For cageless sensors, suspend the dis-placer to an appropriate depth in a liquid having a spe-cific gravity equal to that of the process liquid.

If necessary, use water for wet calibration in the shop.However, this procedure requires compensation forthe difference between the specific gravity of the waterand that of the process liquids. For example, assumethat the process liquid has a specific gravity of 0.7 andthat wet calibration with water (specific gravity of 1.0)is desired. To simulate a process level of 50 percent ofthe input span, a water level of 35 percent is required(0.7/1.0 x 50 percent = 35 percent).

Dry CalibrationRemove the controller and torque tube arm, as asingle unit, from the cage or vessel. Then, whereverthe standard calibration instructions in this manual re-quire a specific process variable for input to the sen-sor, simulate that variable by suspending the properweight (such as a can of sand) from the end of thedisplacer rod. Complete the following Controller andTorque Tube Arm Disassembly and the DeterminingSuspended Weight for Calibration sections before pro-ceeding to the calibration procedure.

Controller and Torque Tube ArmDisassembly

WARNING

To avoid personal injury from contactwith the process liquid, lower the vessellevel below the sensor torque tube arm,or shut off the cage equalizing valvesand drain the cage before proceeding.For closed vessels, release any pres-sure that may be in the vessel beforeremoving the sensor assembly.

When removing the displacer from the displacer rod orremoving the controller and torque tube arm from the

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cage or vessel, refer to the appropriate sensor instruc-tion manual for assistance. The method of removingthe displacer or torque tube arm and attached control-ler will vary with the type of sensor.

For a caged sensor with top equalizing connection, itmay be appropriate to remove the entire cage from thevessel before disassembling.

CAUTION

If the displacer is to be disconnectedfrom the displacer rod before the sensorassembly is removed from the cage orvessel, provide a means of supportingthe displacer to prevent it from droppingand suffering damage. The spuds orstem end pieces on all displacers haveholes suitable for inserting rods or othersupports.

Additionally, a threaded rod may beinstalled into the 1/4-inch 28 UNFthreaded hole in the displacer spud orstem end piece of top-mounted cagelessand all caged sensors. For some top-mounted sensors with long displacers,it may also be possible to remove thesensor through the access hole in thesensor head.

For Type 249BP sensor with the travelstop, the stem end piece pins will se-cure the displacer as long as the travelstop plate is installed and the sensorhead is in position.

Determining Suspended Weight forCalibration

CAUTION

To avoid overloading a torque tubesized for interface or density applica-tions under dry conditions, consult yourFisher Controls sales office or sales rep-resentative for the maximum allowablesubstitute weight Ws that can be usedwith your particular construction.

To determine the total weight that must be suspendedfrom the displacer rod to simulate a certain conditionof liquid level or specific gravity, solve the followingequation:

Ws = Wd - [(0.0361) (V) (SP GR)]

where:

Ws = Total suspended weight in pounds (shouldnever be less than 0.5 pounds). For a unit witha horizontal displacer, make sure the center ofgravity of the substitute weight is where itwould be on the actual displacer.

Note

For liquid level control only, simulatethe lower range limit of the input spanby suspending the displacer from thedisplacer rod. For other values of inputspan, remove the displacer and suspendthe appropriate weight as determined inthe equation above.

Wd = Weight of the displacer, in pounds (determineby weighing displacer).

0.0361 = Weight of one cubic inch of water (specificgravity = 1.0), in pounds.

V = Volume of the displacer in cubic inches, thatwould be submerged at the level required bythe calibration procedure. Or,

V = π/4 (displacer diameter)2 x (length of displacersubmerged)

SP GR = Specific gravity of the process liquid atoperating temperature.

For interface level measurement, the equation be-comes:

Ws = Wd - [(0.0361) (V1) (SP GR1) +(0.0361) (Vh) (SP GRh)]

where:

V1 = Volume of the displacer submerged by thelighter liquid, in cubic inches.

Or,

V = π/4 (displacer diameter)2 x (length of the dis-placer submerged)

SP GR1 = Specific gravity of the lighter liquid at op-erating temperature.

Vh = Volume of the displacer submerged by theheavier liquid, in cubic inches.

Or,

V = π/4 (displacer diameter)2 x (length of the dis-placer submerged)

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Table 2. Minimum and Maximum Limits for Setting Process VariablesApplication Minimum Limit Maximum Limit

Liquid level Displacer must be completely out of liquid Displacer must be completely submerged in liquid

Interface Displacer must be completely submerged in the upperof two process liquids

Displacer must be completely submerged in the lowerof two process liquids

Density Displacer must be completely submerged in liquid havinghighest specific gravity expected

Displacer must be completely submerged in liquidhaving the lowest specific gravity expected

SP GRh = Specific gravity of the heavier liquid atoperating temperature.

Calibration Procedure

WARNING

The following calibration procedure re-quires taking the controller out of ser-vice. To avoid personal injury and prop-erty damage caused by an uncontrolledprocess, provide some temporarymeans of control for the process beforetaking the controller out of service.

Figure 11 shows adjustment locations for the followingsteps, except as otherwise indicated. When calibrat-ing, open loop conditions must exist. One way to ob-tain an open loop is to place the final control elementinto manual control or bypass it. If there is no provisionfor manual control, shut down the process. It is recom-mended that a test pressure gauge be installed in thecontroller output line for subsequent calibration steps.

Several steps in these calibration procedures requiresetting the process variable at its minimum and maxi-mum limits according to table 2. Reverse-acting con-trollers produce the opposite response.

1. Connect a supply pressure source to the controllerand provide a supply pressure suitable for the sensingelement range: 20 psig (1.4 bar) for a 3 to 15 psig (0.2to 1.0 bar) output pressure range or 35 psig (2.4 bar)for a 6 to 30 psig (0.4 to 2.0 bar) output pressure range.

2. Rotate the reset knob to 0.01 minutes per repeat.

3. Rotate the proportional band knob to zero.

4. Set the liquid at the minimum limit (dry displacer).

5. Turn the raise level knob to zero.

6. Adjust the nozzle until output pressure is between0 and 3 psig for a 3 to 15 psig signal range (0 and 0.2bar for a 0.2 to 1.0 bar signal range) or 0 and 6 psigfor a 6 to 30 psig signal range (0 and 0.4 bar for a 0.4to 2.0 bar signal range).

7. Set the liquid at the maximum limit (covered dis-placer).

8. Turn the raise level knob until the output pressure is15 psig for a 3 to 15 psig signal range (1.0 bar for a 0.2to 1.0 bar signal range) or 30 psig for a 6 to 30 psig sig-nal range (2.0 bar for a 0.4 to 2.0 bar signal range).

9. The controller is within its calibration accuracy if theraise level knob is between the 9.0 and 10.0 positions.

10. If the controller is out of calibration, adjust the cal-ibration adjuster as follows:

Note

Loosen the two calibration adjusterscrews (key 45, figure 16), and slide thecalibration adjuster (key 100, figure 16)in the desired direction.

a. If output is below 15 psig for a 3 to 15 psig sig-nal range (1.0 bar for a 0.2 to 1.0 bar signal range)or 30 psig for a 6 to 30 psig signal range (2.0 barfor a 0.4 to 2.0 bar signal range) , move the adjus-tor a small distance away from the pivot to in-crease span. Then repeat steps 4 through 9.

b. If output is above 15 psig for a 3 to 15 psig sig-nal range (1.0 bar for a 0.2 to 1.0 bar signal range)or 30 psig for a 6 to 30 psig signal range (2.0 barfor a 0.4 to 2.0 bar signal range), move the adjustora small distance toward the pivot to decreasespan. Then repeat steps 4 through 9.

Note

If the controller cannot be calibrated,look for other problems as described inthe Troubleshooting section, such as anonperpendicular flapper-nozzle condi-tion, leaky connections, or a bindingdisplacer rod. If none of these tr oubles isapparent, the displacer or torque tube isprobably sized for a different set of ser-vice conditions. Ensure that the displ aceris sized correctly for the application.

StartupAdjustment locations are shown in figure 11.

1. Set the raise level control to the desired controlpoint as determined in prestartup checks step 4.

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14

2. Set the percent proportional band control to 200.

3. Set the reset control to .05 minutes per repeat.

4. Slowly open the downstream and upstream manualcontrol valves in the pipeline and close the manualbypass valve if one is used.

5. With the controller set at the desired control point,narrow the proportional band until a cycling conditionexists. Then broaden the proportional band slightlyuntil stable control is obtained.

6. Adjust the reset control to obtain the highest resetsetting without introducing cycling.

7. To ensure that the optimum proportional band andreset settings have been obtained, momentarily createa load upset. If cycling occurs, broaden the proportion-al band slightly and repeat the load upset until stabilityis attained. In general, the narrowest proportional bandand the highest reset setting that will not produce cycl-ing will provide the best control.

Principle of OperationAll 2502 Series controllers use the same basic pres-sure-balanced relay with a yoked double-diaphragmassembly (figure 12). This relay is connected so thatsupply pressure is fed to the inlet side of the relayvalve and to the fixed restriction. From this restriction,the air pressure goes into the relay chamber on theside of the large diaphragm, and to the nozzle. As longas there is no pressure change on either diaphragm,the relay valve remains in equilibrium with both theinlet and exhaust ends closed.

The area ratio of the large diaphragm to the small dia-phragm is 3 to 1. A 12 psig (0.8 bar) pressure changeon the small diaphragm need only be balanced by a 4psig (0.3 bar) change on the large diaphragm.

A change in liquid level, interface level, or densitychanges the buoyant force exerted on the sensor dis-placer, which in turn imparts a rotary motion throughthe torque tube shaft. The rotary motion is applied tothe controller, which uses a nozzle, bellows, and pneu-matic relay to convert the rotary motion to a standardpneumatic output signal. The output signal is sent to afinal control element. In conjunction with this controlelement, 2502-249 Series controller-sensors are capa-ble of bringing the controlled variable back to a specif-ic control point all the time.

The following descriptions show how the relay worksin conjunction with the standard proportional-plus-resetcontroller, and how the reset relief valve constructionworks.

Type 2502 ControllerAs long as inflow and outflow of the vessel are equal,the beam and flapper remain motionless and allow sup-ply pressure to bleed through the nozzle as fast as itenters the relay through the fixed restriction. A level ordensity change either raises or lowers the displacer andpivots the beam and flapper with respect to the nozzle.

An increase in level or density with direct action, or adecrease with reverse action, moves the beam andflapper closer to the nozzle and restricts the escape ofsupply pressure. This builds up the loading differentialon the side of the large diaphragm and opens the relayvalve to supply pressure inflow.

On the other hand, a decrease in level or density withdirect action, or an increase with reverse action,moves the beam and flapper away from the nozzleand permits supply pressure to bleed through thenozzle faster than it can enter through the fixed restric-tion. This builds up the loading differential on the sideof the small diaphragm, and opens the relay valve toexhaust loading pressure.

The three-way proportional valve can be opened andadjusted to allow some or all of the output pressurechange to feed back to the proportional bellows in or-der to change the proportional band of the controller.This pushes the beam and flapper opposite the way itis being pivoted by the torque tube shaft, counteract-ing the pressure change in the nozzle and again stabi-lizing the relay diaphragm pressure differential. Therelay valve shuts off and maintains a new output pres-sure according to the change in sensed displacer posi-tion.

A wide-open proportional valve permits feedback of allthe output change and produces 100 percent propor-tional response. Closing of this valve produces smallerproportional responses, since part of the outputchange is vented through the valve exhaust and onlythe remainder is available to reposition the bellows.

The reset valve can be adjusted to channel some or allof the proportional pressure into a reset bellows thatopposes proportional bellows action. This automatical-ly dampens the effect of any proportional overcorrec-tion by a set amount per time interval, as long as thereis a deviation from the control point.

Figure 12 illustrates these principles at work in a di-rect-acting right-hand-mounted construction controllingliquid inflow to a vessel, by means of a direct-actingdiaphragm-actuated control valve. Nozzle positionsand bellows connections would be reversed for directaction with left-hand mounting or reverse action withright-hand mounting.

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Figure 12. Direct-Acting Right-Hand-Mounted 2502-249 Series Controller

CD2114-ACJ4081-AC0313-1

Type 2502F Controller with Reset ReliefValveThis construction (figure 13) has a differential reliefvalve used to prevent proportional pressure from ex-

ceeding reset pressure by more than a set value, afeature useful for intermittent control applications. Pro-portional valve output registers in the outer chamber ofthe relief valve as well as in the proportional bellows.

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Figure 13. Type 2502F Controller with Reset Relief Valve

CJ4081-ACU7387-BC0311-2

A sudden increase in the output pressure will cause arapid pressure increase in the proportional bellows andin the outer relief valve chamber. If the outer chamberpressure exceeds that in the inner relief valve cham-ber by the amount of the relief pressure setting, therelief diaphragm will move off the orifice in the reliefvalve, and the pressure in the outer chamber will bleedinto the reset system. This action provides quick reliefof excessive proportional pressure and reduces thetime required by the system to return to the controlpoint.

MaintenanceThe 2502 Series controllers are used in combinationwith 249 Series sensors. Due to the care Fisher Con-trols takes in meeting all manufacturing requirements(heat treating, dimensional tolerances, etc.), use onlyreplacement parts manufactured or furnished by Fish-er Controls.

WARNING

Personal injury or property damage dueto sudden release of pressure, contactwith hazardous liquid, fire, or explosioncan be caused by puncturing, heating,or repairing a displacer that is retainingprocess pressure or liquid. This dangermay not be readily apparent when disas-sembling the sensor or removing thedisplacer. Before disassembling thesensor or removing the displacer, ob-serve the more specific warning pro-vided in the sensor instruction manual.

TroubleshootingWhen troubleshooting, open loop conditions must existunless otherwise stated. When monitoring the processvariable, use the most accurate level indicting devicereadily available. The output signal measuring deviceshould have a corresponding accuracy.

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Table 3 lists some common operating faults, theirprobable causes, and corrective action.

Removing Controller from Sensor

WARNING

To avoid injury in the following steps,turn off the supply pressure and careful-ly release any pressure trapped in thecontroller before breaking any pressureconnection. Provide a bypass for thecontrol device if continuous operationis required during maintenance.

Refer to figure 16 for key number locations, unlessotherwise indicated.

1. Disconnect the supply and output pressure tubingfrom the controller.

2. Loosen the hex nut (key 40) that secures the oper-ating arm base or pointer assembly (key 68 or 51) tothe torque tube rotary shaft. Do not lose the two linkbearings (key 87, not shown).

CAUTION

If the hex nut has not been loosened ac-cording to step 2, attempting to removethe controller from the sensor may bendthe rotary shaft or operating arm andlinkage. Be careful that the back of thecontroller case or the heat insulatordoes not drop down and bend the rotaryshaft or shaft extension.

3. Remove any insulating tape from the joint betweenthe controller case and the torque tube arm. Removehe four cap screws (key 39, figure 14) that hold thecontroller or heat insulator to the torque tube arm. Pullthe case straight out from the torque tube arm, easingit over the shaft coupling (key 36, figure 14) if one isinstalled.

4. If the controller has a heat insulator, remove thebutton head cap screws (key 40). Remove four wash-ers (key 53) and the insulator assembly (key 35).

Changing Mounting Method

WARNING

To avoid injury from contact with theprocess liquid, lower the vessel levelbelow the torque-tube arm before pro-ceeding. For closed vessels, release anypressure that may be above the liquid.Also, be careful to avoid overloading athin-wall torque tube and/or overweightdisplacer.

Refer to figure 16 for key number locations.

1. Remove the controller as described previously.

2. A controller is attached to the sensor in one or theother of the mounting positions shown in figure 4.Right hand mount is with the case to the right of thedisplacer when looking at the front of the case. Lefthand mount is with the case to the left of the displacer.For a 249 Series sensor, remove the torque tube armfrom the sensor or vessel and reinstall the torque tubearm in the opposite position according to the appropri-ate instruction manual.

3. Check the desired control action to determine if it isalso necessary to reverse the controller action. Thenozzle block and bellows tubing should be arranged inthe proper position as shown in figure 15.

4. Remove the raise level dial, turn it over, and installit in the desired position. The arrow on it under theword FLOAT should point toward the displacer. On acontroller with indicator assembly, remove two screws(key 41, figure 16), turn the front plate (key 54, figure16) to the side that will have the float arrow pointingtoward the displacer, and secure the plate with thescrews.

5. Install the controller according to the next section.

Installing Controller on Sensor

Note

If the installation is in a location that isnot readily accessible and shop calibra-tion is required, remove the torque tubearm from the cage or vessel before mat-ing the controller to the sensor. Installthe controller on the torque tube arm inthe shop; then calibrate and return thecontroller and torque tube arm assem-bly to the installation.

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Table 3. Troubleshooting Chart for 2502 Series ControllersFault Possible Cause Check Correction

1. Process wanders or cyclesaround setpoint.

1.1 Proportional band or specificgravity adjsutment incorrect orimproperly tuned control loop.

1.1 Insure the prestartupprocedures are completedcorrectly. Tune control loop.

1.1 If stable control cannot beattained and all other elements arefunctionally correct, examine otherossible causes related to thecontroller/transmitter.

1.2 Supply pressure varying orincorrect supply pressure setting.

1.2 Use input pressure gauge tomonitor stability. Make sureregulator IN supply pressure iswithlin limits.

1.2 Apply correct supply pressure.It is recommended to use oneregulator per instrument.

1.3 Sensor not plumb and is incontact with sidewall or leak indisplacer.

1.3 Check cage vessel and stillwellinstallation, or for leaking displacer.

1.3 Make sure the displacer anddisplacer rod hangs freely. Makesure linkage is tight. Replacedisplacer if leaking.

1.4 Relay malfunction. 1.4 Check for relay malfunction byusing the testing relay deadbandprocedure

1.4 Depress plunger to clean outthe fixed restriction. Replace orrepair relay using the procedure inthe Maintenance section.

2. Controller controlling off setpointor switching point.

2.1 Supply pressure not setcorrectly.

2.1 Make sure regulator supplypressure is set correctly. Make sureregulator IN supply pressure iswithin limits.

2.1 Reset the supply regulatorpressure. If the condition occursagain, rebuilld or replace regulator.Provide a regulator input pressurewithin regulator limits.

2.2 Leak in the controller loop. 2.2 Use soap and water to checkfor internal and external leaks.

2.2 Replace or repair leaking partsas necessary.

2.3 Leaking displacer. 2.3 Insure the displacer is not fillingwith process fluid.

2.3 Refer to sensor maintenanceprocedures in the appropriatesensor instruction manual.

2.4 Flapper adjustment. 2.4 Insure the flapper is not looseon the torque tube shaft and iscentered on the nozzle.

2.4 Replace or tighten flapperassembly as necessary and/orcenter flapper on nozzle.

2.5 Process variable changed. 2.5 Insure the process variable hasnot changed from originalcalibration settings or, displacer notdesign specific gravity of process.

2.5 Change process variable backto original sepcification orrecalibrate. If necessary, providereplacement displacer of correctsize and recalibrate.

3. Controller cannot attain fulloutput range.

3.1 Supply pressure not setcorrectly.

3.1 Make sure supply pressure isset correctly. Make sure regulatorIN supply pressure is within limits.

3.1 Reset the regulator pressure. Ifproblem reoccurs, replace orrebuild the regulator. Insureregulator IN supply pressure iswithin limits at all operating levels.

3.2 Flapper adjustment. 3.2 Insure the flapper is not looseon the torque tube shaft and iscentered on the nozzle.

3.2 Replace or tighten flapperassembly as necessary and/orcenter flapper on nozzle.

3.3 Process variable changed. 3.3 Insure the process variable hasnot changed from originalcalibration settings or, fromdisplacer design specific gravity.

3.3 Change process variable backto original specificaton orrecalibrate. If necessary, providereplacement displacer of correctsize and recalibrate.

3.4 Relay malfunction. 3.4 Check for relay malfunction byusing the testing relay deadbandprocedure.

3.4 Depress plunger to clean outthe fixed restriction. Replace orrepair relay using the procedure inthe Maintenance section.

3.5 Leaking controller loop. 3.5 Use soap and water to checkfor internal and external leaks.

3.5 Replace or repair leaking partsas necessary.

4. Controller remains at full or zerooutput pressure.

4.1 Supply or output pressuregauge malfunction

4.1 Insure the pressure gauges areregistering correctly.

4.1 Replace pressure gauges. Usecorrective action given in section 3of this table.

4.2 Flapper adjustment. 4.2 Insure the flapper is not looseon the torque tube shaft. Insure theflapper is centered on the nozzle.

4.2 Replace or tighten flapperassembly as necesary and/orcenter flapper on nozzle.

Perform step 1 only if adding a heat insulator to aunit that does not have one. Key numbers in thisstep are shown in figure 14.

1. To install the heat insulator, secure the shaft exten-sion (key 37) to the torque tube assembly rotary shaftwith the shaft coupling (key 36). Tighten both setscrews (key 38), with the coupling centered as shown

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Figure 14. Heat Insulator Shown Installed on 249 Series

20A7423-C/DOC

in the figure. Then mount the insulator assembly (key35) on the controller case with four washers (key 53)and button-head cap screws (key 40). Tighten thescrews.

CAUTION

In the following step, avoid bending thetorque tube rotary shaft of the torquetube assembly. Bending or side loadingof this shaft could cause erroneousreadings. Additionally, make sure theball bearing assembly (key 12, figure 16)is removed from the case (key 1, figure16) to provide clearance when installingthe case on the sensor.

2. Remove the bearing assembly (key 12) from thecase (key 1).

3. Carefully slide the controller case straight in, guid-ing the bearing assembly (key 12), operating arm baseor pointer assembly (key 68 or 51, figure 16) over therotary shaft and easing an attached heat insulator overthe shaft coupling (key 36, figure 14) if necessary. Se-cure the case or insulator to the torque tube arm withthe four cap screws (key 39, figure 14).

Figure 15. Nozzle, Flapper, and Tubing Arrangementsfor Various Actions and Mountings

AV2323-AAV2322-AB0995-2/IL

Note

If a heat insulator is used, do not insu-late its exterior.

4. On a unit without a heat insulator, tape the jointbetween the case and torque tube arm to minimize theentrance of atmospheric moisture around the torquetube rotary shaft.

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20

5. Install and tighten the bearing assembly (key 12) inthe case (key1). Secure the operating arm base or point-er assembly to the rotary shaft by tightening the hex nut(key 40, figure 16). Connect the supply and output pres-sure tubing and perform the calibration procedure.

Changing Proportional, Reset, orDifferential Relief Valve1. Remove the proportional band valve assembly (key36, figure 16) by unscrewing it from the relay base(key 23, figure 16). Install the desired replacementassembly, or a 1/8-inch (3.2 mm) NPT pipe plug intothe proportional band tapping if testing relay deadband.

2. To change the reset restriction valve assembly (key91), remove the two mounting screws (key 182) locatedon the back side of case. Install the replacement valveassembly, and reconnect the tubing connections.

3. Remove the differential relief valve assembly (key186, figure 16) by removing the two mounting screws(figure 11) that anchor the valve to the manifold (key184, figure 16). Install the valve with the arrow pointingto the same letter(s) as before removal, unless it isdesired to change the relief action.

Testing Relay Dead Band1. Replace the proportional band adjustment assem-bly with a 1/8-inch (3.2 mm) NPT pipe plug accordingto the Changing Proportional, Reset, or DifferentialRelief Valve section.

2. Turn on the supply pressure and set it to 20 or 35psig (1.4 or 2.4 bar).

3. By changing the process variable and adjusting theraise level control, set the output pressure to 15 or 30psig (1.0 or 2.0 bar). While monitoring the output pres-sure, slowly change the process until an output pres-sure change can just be detected, and record the val-ue of the process variable at the detection point.

4. Change the process variable in the opposite direc-tion until another output pressure change can be de-tected, and again record the value of the process vari-able. If the difference between the two recordedvalues (the dead band) is more than 0.2 percent of themaximum displacer length, the relay will have to bereplaced or repaired according to the Changing Relayand the Disassembling Relay sections.

5. Turn off the supply pressure, remove the pipe plug,and install the proportional band adjustment assembly.

Changing RelayThe relay may be removed for cleaning or repair, andmust be taken off to remove the lower bellows.

1. On a controller with indicator assembly, loosen thetwo lower screws (key 96, figure 17) of the relay caseand slide out the indicator base plate (key 53, figure 16).

2. Disconnect the tubing (key 11, figure 16) from therelay.

3. Remove both mounting screws, the relay, and therelay gasket (keys 43, 34, and 22, figure 16).

4. Install a new gasket, the replacement relay if nec-essary, and both mounting screws. Reconnect the tub-ing. On a controller with indicator assembly, slide thebase plate under the two lower screws of the relaycase, align the plate so that the pointer will read prop-erly, and tighten the screws.

Replacing BellowsKey numbers are shown in figure 16.

1. To gain access to the lower bellows, remove therelay according to the Changing Relay section.

2. Remove the upper and lower bellows frame screws(key 96) that hold both bellows assemblies to the bel-lows frame. Unscrew each bellows from the spacer(key 98), being careful not to lose the O-ring (key 57,not shown) from the spacer end of the bellows.

3. Inspect each bellows and O-ring and replace if nec-essary, using an unpainted bellows for a 3 to 15 psig(0.2 to 1.0 bar) range and a red bellows for a 6 to 30psig (0.4 to 2.0 bar) range. Be sure to install the O-ringat the spacer end of the bellows.

4. Install each bellows by screwing it down over thestud (key 97, not shown) protruding from each end ofthe spacer. Secure with a bellows frame screw, andinstall the relay according to the Changing Relay sec-tion if it was removed.

5. Perform the calibration procedure and any othernecessary part of the calibration sequence.

Reversing Action

Note

The following procedure will be neces-sary to restore previous action if themounting method has been changed.Key numbers are shown in figure 16.

1. Remove two screws (keys 63 and 64), two sealrings (key 55), and the nozzle block (key 101). Checkseal ring condition and replace rings as necessary.

2. Install the nozzle block, seal rings, and screws onthe opposite side of the beam as shown in figure 15.Disconnect the proportional band tubing (key 76) andone of the two pieces of reset tubing (key 75) from thebellows frame (key 94) and reconnect them in theproper orientation as shown in figure 15.

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21

Note

Beam overtravel can jam the flapperagainst the nozzle if the following stepis not performed.

3. Remove the flapper screw (key 93), lockwasher(key 84), and flapper (key 60). Invert the flapper sothat the flapper hook is on the opposite side of thebeam from the nozzle (key 58), and secure with thelockwasher and screw.

4. Perform the calibration procedure and any othernecessary part of the calibration sequence.

Disassembling RelayDisassembly can be accomplished in the followingsteps. Key numbers are shown in figure 17.

1. Remove the relay according to the Changing Relaysection.

2. Remove the orifice assembly (key 88) and checkfor orifice plugging or damage. Replace the O-ring(key 90) before installing the orifice assembly.

3. Remove the casing screws (key 96) and washers(key 98), casing assembly (key 85), and top dia-phragm (key 91). On a high-temperature relay alsoremove the top gasket (key 100) that covers the topdiaphragm.

4. Remove the spacer ring (key 84), diaphragm as-sembly (key 86), and relay spring (key 92) from therelay body (key 83). On a high-temperature relay alsoremove the bottom gasket (key 99) from underneaththe diaphragm assembly.

5. Remove the screws (key 97), spring plate (key 95),spring plate gasket (key 94), spring (key 93), andvalve plug (key 87).

6. Inspect the diaphragms and gaskets and replace ifnecessary. Also replace the spring and valve plug ifthey show signs of corrosion. The lower diaphragmcomes as part of an assembly and must be installedas such. Clean all parts thoroughly before assembling.

7. Put the valve plug and its spring in the relay body.Replace the spring plate gasket and spring plate andsecure with four screws.

8. Place the relay spring in the relay body and, on ahigh-temperature relay, install a bottom gasket. Installthe diaphragm assembly, spacer ring, and top dia-phragm on the body so that all flow passage holes arelined up. On a high-temperature relay also install agasket over the top diaphragm.

9. Put the casing assembly on the top diaphragm sothat the lugs on the casing and spacer ring line up andare also lined up with the body lug.

10. Install the casing screws and tighten them slowlyto ensure a good seal.

11. Install the assembled orifice assembly, and installthe relay according to the Changing Relay section.

Parts OrderingWhenever corresponding with the Fisher Controlssales office or sales representative about this equip-ment, always mention the controller type number andthe serial number found on the unit nameplate (figure11). When ordering replacement parts, also state thecomplete 11-character part number of each requiredpart as found in the following parts list.

Parts KitsKey Description Part Number

Controller Parts KitContains keys 12, 15, 21, 24, 38, 55, 57, 58, 60, 62, 63, 64, 77, 79, 84, 86, 87, 93, 101, and 187

Standard Temperature R2502 X0L52High Temperature R2502 X0H52

Relay Parts KitContains keys 22, 85, 86, 87, 88, 90, 91, 92, 93 and 94,(99 and 100 high temp only)Standard Temperature RRELAY X0L12High Temperature RRELAY X0H12

Relay Replacement KitContains keys 22, 43, and the relay assembly

Standard Temperature RRELAY X0L22High Temperature RRELAY X0H22

Heat Insulator Parts KitContains keys 35, 36, 37, 38, 39, 40, and 53 R2500XH 0012

Parts ListHeat Insulator (figure 14)35 Heat Insulator Assembly, stainless steel 22A0033 X01236 Shaft Coupling, stainless steel 1A5779 3503237 Shaft Extension, K-Monel 1B6815 4002238 Set Screw, stainless steel (2 req’d) 1E6234 X002239 Cap Screw, steel, pl (4 req’d) 1A3816 2405240 Cap Screw, steel, pl (4 req’d) 1V2395 2898253 Washer, carbon steel, pl (4 req’d) 1B8659 28982

Controller Common Parts (figure 16)1 Pilot Case Back, zinc

Types 2502 and 2502C 1J4157 44012Type 2502F 23A2073 X012

2 Pilot Case Cover, aluminum 50B9454 X0123 Door Handle, steel, pl 1C8972 250824 Door Handle Shaft (not shown),

stainless steel 1C8984 140125 Machine Screw, stainless steel 1C8958 X00226 Washer Spring, stainless steel 1C8970 360327 Door Hook, steel, pl 1C8971 250828 Elastic Stop Nut, steel, pl 1C8959 X00129 Drive Pin, (2 req’d) 1C8991 X0022

11 Relay TubingCopper 17A9100 X012Stainless steel (2502 and 2502C only) 17A9100 X022

12* Ball Bearing Ass’y, brass, pl 1C8983 000A2

*Recommended spare part.

2502 Series

22

Figure 16. 2502 Series Controller Constructions

30A8942-H/DOC

43A2366-H/DOC

30A8943-H/DOC

2502 Series

23

Key Description Part Number

13 Retaining Ring, steel, pl (zinc casecover only) (2 req’d) 1A4658 28992

14* Gauge Glass, glass, (2 req’d) 0T0192 0604215* Gauge Glass Gasket, neoprene, (2 req’d) 0T0191 0408218 Instruction Label, aluminum 29A2834 X01219* Pressure Gauge (2 req’d)

Brass, triple scale0-30 psig/0-0.2MPa/0-2.0 bar 11B8577 X0120-60 psig/0-0.4MPa/0-4.0 bar 11B8577 X022

Stainless steel, triple scale0-30 psig/0-0.2MPa/0-2.0 bar 11B8583 X0120-60 psig/0-0.4MPa/0-4.0 bar 11B8583 X022

21* Cover Gasket, nitrile 1C9198 0643222* Relay Gasket

Standard, neoprene 1C8974 03012High-temperature, rubber 1N8738 04142

23 Relay Base, aluminum 47A0950 X01224* Relay Base Gasket (not shown)

Standard, neoprene 1C8973 03012High-temperature, rubber 1N8739 04142

29 Drive-lok Pin, stainless steel 1C8989 X001231 Shaft Clamp Screw, stainless steel 1B4514 3517234 Pilot Relay (parts shown under separate heading)

Standard 22B0463 X012High-temperature 22B0462 X012

35 Level Adjustment Ass’y 10A8939 X0A236 Proportional Valve Ass’y 10A9122 X04238* Filter Gasket (not shown)

Standard, neoprene 1C8986 03012High-temperature, rubber 1N8740 04142

39 Cap Screw (not shown), steel, pl (2 req’d) 1C3988 X002240 Hex Nut, stainless steel 1L2863 3899241 Screw, steel, pl (4 req’d for Type

2502C and FC, 2 req’d for all others) 1C9419 X001242 Machine Screw, stainless steel, (8 req’d) 1V7435 X002243 Machine Screw, stainless steel (2 req’d) 1A3776 X001244 Machine Screw, steel, pl (4 req’d) 1A5733 X001245 Machine Screw, stainless steel (2 req’d) 1H2675 X001247 Spring (not shown), stainless steel 1J4234 3702249 Machine Screw, stainless steel (13 req’d) 1B7839 X001250 Screen, stainless steel 0L0783 4306251 Pointer Ass’y (Type 2502C and FC only),

stainless steel/brass, pl 1R2425 X001253 Base Plate, aluminum

(Type 2502C and FC only) 1E8731 1199254 Front Plate, aluminum

(Type 2502C and FC only) 1E8732 1199255* O-Ring, (3 req’d)

Standard, nitrile 1D6875 06992High-temperature, fluoroelastomer 1N4304 06382

57* O-Ring (not shown)Standard, nitrile 1E2226 06992High-temperature, fluoroelastomer 1N8387 06382

58* Nozzle, stainless steel 1U6391 3513259 Beam, steel, pl 1K8738 2507260 Flapper, Invar(1) 36 1J4162 4113261 Flapper Base, stainless steel 1J4163 3503262* Connecting Link, Monel 1L3796 4101263 Sealing Screw, stainless steel 14A5721 X01264 Screw, stainless steel 24A5720 X01265* Bellows Ass’y, brass (2 req’d)

3 to 15 psig (0.2 to 1.0 bar) 14A5726 X0126 to 30 psig (0.4 to 2.0 bar) 14A5726 X032

66 Level Set Arm, steel, pl 1J4164 2507267 Operating Arm, steel, pl 1J4165 2507268 Operating Arm Base, brass, pl

Types 2502 and 2502F only) 1J4166 14022

Key Description Part Number

69 Level Set Pivot Pin, stainless steel 1J4167 3516270 Pivot Base, steel, pl 19A9689 X01271 Spring Washer, stainless steel 1H8851 X001272 Washer, stainless steel

Types 2502 and 2502FC, (2 req’d) 1E8730 X0012Type 2502C (4 req’d) 1E8730 X0012

74 Washer, stainless steel, (6 req’d) 6100057 0X1275 Reset Tubing Ass’y (2 req’d),

copper 1J4169 000A2stainless steel (2502 and 2502C only) 19A1887 X012

76 Proportional Band Tubing Ass’ycopper 1J4170 000A2stainless steel (2502 and 2502C only) 1J4170 X0012

77* Bellows Frame Gasket (not shown)Standard, neoprene 1H2654 03012High-temperature, rubber 1N8735 04142

78 Spacer (not shown), brass 1J6198 1512279* Bellows Gasket (2 req’d)

Standard, neoprene 1D3970 03012High-temperature, rubber 1N8736 04142

80 Machine Screw, stainless steel, (4 req’d) 1H2678 X001281 Machine Screw (not shown)

stainless steel, (2 req’d) 1P4373 X001282 Machine Screw, stainless steel, (4 req’d) 1B2752 X002283 Lock Washer, stainless steel (2 req’d) 6100081 0X1284 Lock Washer, stainless steel 1C3162 X001285 Cap Screw, stainless steel, not shown (4 req’d) 1A3816 K001286 Machine Screw, stainless steel (2 req’d) 1A8664 X00A287* Link Bearing (not shown)

stainless steel (2 req’d) 1L3795 4620288 Machine Screw (not shown),

stainless steel, (4 req’d) 1J4159 X001289 Machine Screw, stainless steel, (2 req’d) 1H8162 X001291 RESET Restriction Valve Ass’y

Types 2502 and 2502CStandard 19A4357 X012High-temperature 19A4357 X022

Type 2502F and 2502FCStandard 19A4359 X012High-temperature 19A4359 X032

93 Machine Screw, stainless steel 1B8776 X001294 Bellows Frame, aluminum 2H2653 0801295 Bellows Frame Base (not shown), steel, pl 1J4160 2514296 Bellows Screw, brass, pl (2 req’d) 1D3976 1402297 Bellows Stud (not shown), brass 1H2658 1401298 Spacer, zinc 1H2659 4401299 Cross Spring, stainless steel (2 req’d) 1H2660 37032

100 Calibration Adjuster, zinc 2H2662 44012101 Reversing Block, zinc 26A0975 X012180 Pipe Nipple (not shown) Type 2502F

and 2502FC only), steel 1C5599 26232181 Relief Tubing Ass’y (Type 2502F and

2502FC only), copper 13A2077 X012182 Machine Screw, stainless steel, (2 req’d)

Types 2502 and 2502C (not shown) 1B7839 X0012Type 2502F and 2502FC 1C8969 X0012

183* O-Ring (2 req’d), Type 2502F and 2502FC onlyStandard, nitrile 1D6875 06992High temperature, fluoroelastomer 1N4304 06382

184 Manifold, aluminum, (Type 2502F and2502FC only) 23A2072 X012

185 Manifold Nipple, aluminum (Type 2502F only) 13A2074 X012186 Differential Relief Valve Ass’y (Type 2502F and 2502FC only)

Standard 21A6447 X0A2High temperature 21A6447 X012

187 Sleeve, plastic 16A0976 X012

*Recommended spare part.1. Invar is a mark owned by Carpenter Technology Corp.

2502 Series

24

Figure 17. Relay Constructions

22B0463-A/DOC

22B0462-A/DOC �������������� ���� ���

Key Description Part Number

188* 0-Ring (Type 2502F and 2502FC only),Standard 1C8538 06992High temperature 1C8538 X0052

215 Nameplate, metal 12B6337 X0A2

Relay (figure 17) 83 Relay Body, aluminum/brass 48A3776 X01284 Spacer Ring, aluminum 38A3778 X01285 Casing Ass’y, aluminum/steel 12B0460 X01286* Diaphragm Ass’y

Standard, nitrile/nylon 18A2451 X012High-temperature, polyacrylate/nylon 18A2451 X092

87* Valve Plug, brass 0Y0617 1401288* Orifice and Core Ass’y, brass 12B0468 X01290* O-Ring, nitrile, (2 req’d)

Standard 1D6875 06992High temperature 1N4304 06382

Key Description Part Number

91* Top DiaphragmStandard, nitrile 1L5556 02042High-temperature, polyacrylate 1K6999 X0012

92 Relay spring, steel, pl 1C8961 2701293 Valve Spring, stainless steel 0X0836 3702294* Spring Plate Gasket

Standard, neoprene 1H2696 03012High-temperature, rubber 1K7000 04142

95 Spring Plate, steel, pl 1H2697 2507296 Machine Screw, stainless steel, (6 req’d) 1A3294 X002297 Machine Screw, stainless steel (4 req’d) 1A8664 X00A298 Washer (standard only), stainless steel (6 req’d) 1P8261 X001299* Bottom Gasket (high-temperature only), rubber 1K7001 04142

100* Top Gasket (high-temperature only), rubber 1K7002 04142

*Recommended spare part.

For information, contact Fisher Controls:Marshalltown, Iowa 50158 USACernay 68700 France Sao Paulo 05424 BrazilSingapore 128461

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Printed in U.S.A.

�Fisher Controls International, Inc. 1977, 1994; All Rights Reserved

Level-Trol, Fisher, Fisher-Rosemount, and Managing The Process Better are marks owned by Fisher Controls International, Inc. or Fisher-Rosemount Systems, Inc.All other marks are the property of their respective owners.