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dial provides a thermal system adjustment feature assur-ing maximum accuracy in sensing liquid temperaturechanges.

The ATG is bidirectional and provides temperature com-pensated reverse registration in those applications wherebidirectional flow and registration is desired. In addition tocorrecting for temperature changes, the unit also pro-vides the means for adjustment of registration.

Principle of Operation

Specifications

Issue/Rev. 0.1 (2/99) Bulletin SS01037

ATG UniversalTemperature Compensator

A characteristic of all liquids is that a change in volumeoccurs with a change in temperature. This thermal coeffi-

cient of expansion varies with each liquid. The meas-urement of most liquids is based on net volume, definedas volume at a referenced base temperature (60F) forthe petroleum industry in the U.S.A. for example. Whenmetering liquids, the temperature is usually other than thebase temperature and can also vary during the meas-urement. The difference between gross metered volumeand net volume will depend on the coefficient of expan-sion of the liquid and the difference between averagemetered liquid temperature and base temperature.

Meters equipped with the ATG Automatic TemperatureCompensator provide net registration. The net registra-tion is based on continuous integration of gross metered

volume and temperature regardless of flow rate and tem-perature changes. It is also based on the coefficient ofexpansion of the particular metered liquid.

The ATG is designed and manufactured not only as aprecision instrument, but also to withstand the ambientconditions of sand, dust, humidity, and temperature ex-tremes normally encountered. The unit can be checkedin the laboratory with precision thermometers assuringthis type of accuracy in actual field use.

Features

The ATG Temperature Compensator provides a continu-

ous, non-cyclic output as it does not utilize clutches, cams,or ratchets. This continuous output is necessary whereprover volumes are relatively small as encountered withmechanical displacement provers and when providing asignal output for certain instruments to avoid hunting.

The thermal system temperature bulb is not installed in athermal well, but is mounted in the meter housing or adap-tor so that it is exposed directly to the metered fluid,providing fastest possible response to temperaturechanges. Even though directly exposed to the liquid, bulbresponse is not affected by operating pressure changes.Bellows movement is .002" per degree Fahrenheit bulbtemperature change providing a high degree of resolutionin converting temperature change to linear motion.

Two types of ATGs are available. These are termed Stan-dard and LPG. The standard unit is used for gravityranges of 0-110 API and 1.075-.580 specific gravity orcoefficient of expansion ranges of .0003-.0011/F and.005-.0020/C. The LPG unit is used for specific gravityranges of .600-.500 or coefficient of expansion ranges of.0010-.0025/F and .0018-.0045/C.

The gravity dial provides selection of liquid coefficients ofexpansion over a wide range. The large circumference ofthe dial provides a high degree of resolution in selectingthe desired basis of correction. External positioning of this

ATG Universal Temperature Compensator

Figure 1

(Primary Gear

System Not

Illustrated)

Secondary Gear

System and

Roller and

Disk Integrator

Registration AdjustrmentGravity Selector System

Thermal

System

The Most Trusted Name In Measurement

Smith MeterTM Temperature Compensator

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Page 2 SS01037 Issue/Rev. 0.1 (2/99)

Bulb

ro uc e ows

Ambient Bellows

Capillary Tubes

Principle of Operation

The ATG consists of four basic subsystems. These are: athermal system, a gravity selector (coefficient of expan-sion selector), a primary gear system, and a secondarygear system which includes an infinitely variable rollerand disc integrator.

Thermal System

The thermal system consists of the bulb and bellowsassembly and the ambient bellows assembly. The bulb isimmersed in the metered liquid wherein temperaturechanges cause a change in volume of the bulb fillingliquid. This volume change is transmitted through the cap-illary tube to the product bellows providing linear move-ment of the bellows in response to bulb temperaturechange. Both the product bellows and ambient bellowsincrease in length with an increase in ambient tempera-ture. Design is such that an increase in ambient bellowslength causes a decrease in length of the complete ambi-ent bellows assembly. The ambient bellows assemblythen compensates for changes in length of the product

bellows, and other components in the unit, due to ambi-ent temperature changes.

Gravity Selector

The gravity selector system provides for selection of tem-perature compensation based on the coefficient of ex-pansion of the particular metered liquid. It consists of alinkages assembly with a movable pivot point to propor-tionately increase or decrease the effective thermal sys-tem movement based on a given selection. Effective ther-mal system movement is strictly dependent on tempera-ture change and is independent of the metered liquidscoefficient of expansion. Position of the pivot point is indi-cated on a graduated dial in terms of API Gravity and APIGroup, specific gravity, or coefficient of expansion. How-ever, for more accurate compensation, the ATG shouldbe recalibrated following a change of the gravity selectorsetting.

Gear System

The gear system of the ATG consists of primary, second-ary, and planetary gear subsystems. The output of theprimary gear train is 13% greater than the input in thestandard ATG and 31% greater in the LPG-ATG. Correc-tion is accomplished by subtracting. The secondary geartrain subtracts revolutions from the ATG output shaftthrough the planetary gear system. The rate of this sub-traction (percent change) is determined by the ratio posi-tion of the roller on the disc.

The roller and disc integrator is a variable speed trans-mission device which automatically combines the effectsof thermal linear motion (produced by the thermal andgravity selector systems) and gross meter revolutions. Itis part of the secondary gear train and determines theamount of subtraction from the primary gear train.

Figure 2 Thermal System

Figure 3 Gravity Selector

Position of the roller on the disc is controlled by producttemperature through the thermal and gravity selector sys-tems. Disc rate is fixed in direct proportion to gross me-tered volume. A reduction in product temperature movesthe roller toward the center of the disc resulting in fewerroller revolutions. Fewer revolutions of the roller result in

a reduction of the amount of subtraction from the primarygear train, producing higher net registration. Increasingliquid temperatures, of course, have an opposite effectsince the roller is moved toward the outer edge of thedisc, increasing roller revolutions per disc revolution. Sub-traction through the planetary system is greater resultingin lower net registration.

The roller and disc integrator serves as a control element,thus, the primary gear train carries the majority of theaccessory torque load.

Movable

Pivot

Point

C of E

Dial

Dial and

Pivot

Adjustment

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Issue/Rev. 0.1 (2/99) SS01037 Page 3

TemperatureSensing Bulb

Product Bellows

GravitySelector

InputFromMeter

MoveablePivot Point

Disc

Roller

SecondaryGearTrain

Gear System

Output to Register

PlanetarySystem

PrimaryGearTrain

AmbientTemperature

Bellows

ThermalSystem

Figure 4 Gear System

Temperature Range

In addition to covering a wide range of coefficients ofexpansion, the ATG also covers a wide temperature range.Temperature range limits are determined by two factors:the thermal system and the amount of mechanical cor-rection in the device. The thermal system range is 100F,150F, or 200F depending on maximum operating tem-perature (see Characteristics). The total mechanical cor-rection range is 15% for the standard ATG and 30% forthe LPG-ATG. Figure 5 illustrates the temperature range

for both standard and LPG units. Curves A and A1

definethe mechanical correction limits of the standard ATG. Band B1define the mechanical correction limits of the LPG-ATG. C and C1define the thermal system limits. A - A1

and B - B1may be shifted up or down by providing specialgearing in the meter or dual head adaptor. C - C1may beshifted up or down by providing special filling for the ther-mal system.

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Page 4 SS01037 Issue/Rev. 0.1 (2/99)

Examples

Product Coefficient of Operating SpecialNo. Thermal Expansion Temperature Range Special Gearing Bulb Filling

1 0.00042/F 150F to 265F Yes Yes

2 0.00060/F 50F to 170F No Yes

3 0.00170/F -30F to 70F Yes Yes

Note: These charts are based on correction to reference (base) temperatures of 60F or 15C. To determine mechanical correction for other basetemperatures, shift the temperature scale so that the desired base temperature coincides with the present 60F or 15C.

.0003

A

C

Example 1

Example 2

C1

Standard ATG

.0005 .0007

.0005 .0010 .0015 .0020

.0009 .0011 / F

/ C

/F

/C

Coefficientof

Expansion

Temperature-DegreesFahre

nheit

-100

-50 -50

0

50

0

100

50

150

200100

250

150300

.0008

B

C

C1

LPG ATG

.0012 .0016

.0015 .0020 .0025 .0030

.0020 .0024

B1

Temperature-DegreesCenti

grade

Example 3

.0035 .0040 .0045

Figure 5

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Issue/Rev. 0.1 (2/99) SS01037 Page 5

Standard ATG LPG-ATG

Correction Range 0-110 API gravity, 1.075-.580 .600-.500 specific gravity at 60/60Fspecific gravity at 60/60F or 15/15C, or 15/15C, .0010-.0025/F or .0018-.0045/C.0003-.0011/F or .005-.0020/C coefficient of expansion coefficient of expansion

Temperature Range See Figure 5

Thermal Systems Standard: 0F to 150F (-15C to 65C) rangeSpecials: -50F to 100F, 50F to 200F, 125F to 225F, 175F to 275F, 175F to 375F, 225F to 425F,275F to 475F, 325F to 525F

Ambient TemperatureRange -30F to 130F (-35C to 55C)

Linearity 1F/100F (.5C/50C) (See Figure 10)

Hysterisis Less than .25F (.15C)

Time Constant 50 seconds (to effect 2/3 response to step T)

Registration One revolution of adjustment screw One revolution of adjustment screw equals 1.2%,Adjustment equals 0.6%, CW decreases registration CW decreases registration

When an ATG is ordered as part of a meter assembly, itis only necessary to specify minimum, maximum, andnormal operating temperatures and the basis of correc-tion (specific gravity at 60F or 15C, API Gravity at 60For API Group for petroleum liquids, and coefficient of ex-

pansion for non-petroleum liquids). Meters ordered withLPG meter trim and ATG will automatically be suppliedwith LPG-ATG. If the unit is to be adapted to a meter inthe field, specify the model and serial numbers of themeter in addition to operating conditions.

Assembly 518866-001 (ATG with ventilated extensionshould be used for temperatures above 200F [95C]).

If the ATG is to be mounted above a set-stop counter oron a stepper-motor driven by a turbine meter, specifySeries 519141 and whether 26, 42, or 52 inch capillarylength is desired.

There are several variations in the ATG which affect in-terchangeability. When ordering replacement or standbyunits, use the following chart to determine correct assem-bly number.

Standard ATG LPG-ATG

Input Coupling Capillary Length 96% Input1 100% Input2 96% Input1 100% Input2

(A) 42 inches 516727-001 519141-001 516727-021 519141-02152 inches 516727-003 519141-003 516727-023 519141-02326 inches 516727-005 519141-005 516727-025 519141-025

(B) 42 inches 516727-002 516727-02252 inches 516727-004 516727-02426 inches 516727-006 516727-026

(A) S and T meter models, E3-S1 through H8-S1, dual-head adaptor with ATG, ventilated extension with ATG, ATG mounted on set-stop counteror large numeral counter.

(B) W, D, and M meter models, B-170 through 875, C2-S1 (C2-S1 through S7), S7 through H8-S3, S5, S6, and S7, J10-S1, S3, S5, S6, and S7through M16-S1, S3, and S5.

1 96% input for all ATGs supplied as part of meter assembly, dual-head adaptor with ATG, and ventilated extension with ATG.

2 100% input for all ATGs mounted on set-stop counter, large numeral counter, or turbine meter stepper motor.

Installation

ATG units are normally supplied as part of a meter as-sembly or dual-head adaptor (where both gross and netregistration are desired). Within the limits of the capillarytube length, they may be installed remotely or as a part ofthe meter accessory stack on ventilated extensions forhot oil applications or between set-stop counter andcounter-printer if presetting on a gross basis and registra-tion or ticket printing on a net basis is desired. (Series519141 ATG units necessary for this application.)

If the ATG is located remote from the meter proper or ifused with a turbine meter stepper-motor, an accessorytemperature well (Figure 7) is available for welding intothe piping system. When the remote temperature well kitis used, it is desirable to locate the ATG and well suchthat the minimum length capillary tube can be utilized.Standard capillary lengths are 26, 42, and 52 inches.

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Page 6 SS01037 Issue/Rev. 0.1 (2/99)

Meters supplied with ATG are higher than those withstandard calibrators. Distances shown are from centerline of flange to top of meter (X). For other dimensions,refer to appropriate meter bulletin.

X-Dimension (Inches)

Model Dimension

S-13 11.2"

K-13 15.0"

S-28 10.7"

W-28 14.6"

D-28 15.1"

M-28 15.1"

Figure 6 Figure 7 Thermal Well

Model S1 S3 S5 S6 S7

C2 15.7" 18.6" 18.6" 17.5" 17.5"

E3 15.4" 16.8" 16.8" 18.9" 20.3"

F4 16.4" 17.9" 17.9" 18.4" 20.3"

G6 17.0" 18.8" 18.8" 20.4" 21.2"

H8 19.6" 21.4" 21.4" 23.3" 24.5"

J10 24.1" 24.7" 24.7" 24.2" 26.9"

K12 31.0" 30.9" 30.9"

M16 37.6" 37.6" 37.6"

X-Dimension (Inches)

X

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Issue/Rev. 0.1 (2/99) SS01037 Page 7

Figure 9

Ventilated

Extension

With ATG

Single Head

Adapter With

ATG

Offset Dual Head

Adapter With ATG

5.7"(145)

Specify

ExtensionLength

When

Ordering

(8" Min. -

10' Max.)

4" Min.

3.6"(91)

8.0"(203)

3.6"(91)

18.0"(457)

Figure 8

Rotatable

3.3"(84)

3.6"(91)

3.8"(97)

2.5"(63)

2.5"(63)

5.8"(147)

10.6"(269)

(168)6.6"

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Figure 10

120F

100F

80F

60F

40F

20F

.880 .900 .920 .940 .960 .980 1.000 1.020 1.040 1.060 1.080

Volume Reduction Factor

BulbTemperature

Linearity - Standard ATGTable 6C

C of E = 0.000526/F

Linearity - LPG ATGAPI Table 24

Specific Gravity - 0.508 (Propane)

Table 24

LPG ATG

Standard ATG

Table 6C

Linearity - Standard ATGTable 6C

C of E = 0.000526/F

Linearity - LPG ATGAPI Table 24

Specific Gravity - 0.508 (Propane)

Revisions included in SS01037 Issue/Rev. 0.1 (2/99):Page 5: Changed Standard Capilary Lenghts to 26, 42 and 52 inches.

Printed in U.S.A. 6/92 FMC Technologies Measurement Solutions, Inc. All rights reserved. SS01037 Issue/Rev. 0.1 (2/99)

Visit our website at www.fmctechnologies.com

The specifications contained herein are subject to change without notice and any user of said specifications should verify from the manufacturer that thespecifications are currently in effect. Otherwise, the manufacturer assumes no responsibility for the use of specifications which may have been changed and areno longer in effect.

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