type 646 electro-pneumatic

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Type 646 Electro-Pneumatic TransducersType 646 electro-pneumatic transducers, shown infigure 1, use a patented converter module thatconverts a 4 to 20 milliampere input signal to aproportional 0.2 to 1.0 bar (3 to 15 psig) pneumaticoutput signal. The converter module uses smallparts of minimum mass, which are balancedsymmetrically around a pivot point at the center ofthe mass. This balanced arrangement results in ahigh performance instrument that reduces sensitivityto vibration.

An integral pneumatic relay provides the highcapacity necessary to drive pneumatic control

valve/actuator assemblies without additionalboosters or positioners. The transducer alsoprovides stable, accurate operation when its outputis transmitted to small volume chambers, such as apneumatic positioner or other pneumatic instrument.Reduced sensitivity to vibration combined with highcapacity and first order lag characteristics make theType 646 transducer ideal for direct mounting oncontrol valve/actuator combinations.

Connectors and piping can be installed with eachType 646 transducer for diagnostic testing.

TYPE 646 ELECTRO-PNEUMATIC TRANSDUCER WITH

TYPE 657 ACTUATOR AND DESIGN E VALVETYPE 646 ELECTRO-PNEUMATIC

TRANSDUCER

W4908-1

W6783-1 / IL

Figure 1. Type 646 Electro-Pneumatic Transducers

Product Bulletin62.1:646April 2007 646 Transducers

646 TransducersProduct Bulletin

62.1:646April 2007

2

SpecificationsInput Signal(1)

4 to 20 mA DC, constant current with 30 VDCmaximum compliance voltage

Equivalent Circuit

The 646 equivalent circuit is a series circuitconsisting of a constant voltage drop (battery) ofapproximately 2.1 VDC and a total resistance of143 ohms. Input is shunted by three 6.8 V zenerdiodes (see figure 2).

Output Signal(1)

0.2 to 1.0 bar (3 to 15 psig) direct acting only

Supply Pressure(1,4)

Recommended: 1.4 bar (20 psig)Minimum: 1.4 bar (20 psig)Maximum: 3.4 bar (50 psig)

Maximum Steady-State Air Consumption(1,2)

Air consumption is proportional to outputpressure. Maximum consumption at 1.0 bar (15psig) output is 0.20 normal m3/hr (7.8 scfh).

Maximum Output Air Capacity(2)

8.0 normal m3/hr (300 scfh) at 1.4 bar (20 psig)supply pressure

Performance(3)

Reference Accuracy: 0.5% of full scale outputspan; includes combined effects of hysteresis,linearity, and deadbandIndependent Linearity(1): 0.5% of full scaleoutput spanHysteresis(1): 0.4% of full scale output spanFrequency Response(1): Gain is attenuated 3 dBat 10 Hz with transducer output signal piped to atypical instrument inputTemperature Effect: 4% of full scale outputspan per 100F (55C) changeSupply Pressure Effect: 0.2% of full scale outputspan per psi supply pressure changeVibration Effect: Less than 1% of full scaleoutput span when tested to SAMA PMC 31.1,Condition 3

Electromagnetic Interference (EMI)(1): Testedper IEC 61326-1 (Edition 1.1). Conforms to theEuropean EMC Directive. Meets emission limitsfor class A equipment (industrial locations) andclass B equipment (domestic locations). Meetsimmunity requirements for industrial locations(Table A.1 in the IEC specification document).Immunity performance is shown in table 1.

Operating Ambient Temperature Limits(4)

40 to 71C (40 to +160F)

Housing

NEMA 3; IEC 529 IP54 weatherproof. Mountinstrument with vent on side or bottom ifweatherproofing is a concern.

Electrical Classification

Intrinsic Safety, Explosion proof,Dust-Ignition proof, DIV 2,

Intrinsic Safety, Explosion proof,Non-incendive, Dust-Ignition proof,

Intrinsic Safety, Flameproof, and Type n

Refer to tables 2, 3, and 4 for additionalinformation.

Construction Materials

Housing, Cap, and Relay Body: Die castaluminum with less than 1% copper

Adjustments

Zero and Span: Trim potentiometers (20 turn) forzero and span adjustments are located under thehousing cap

Connections

Supply and Output Pressure: 1/4 NPT internalconnectionVent: 1/4 NPT internalElectrical: Standard 1/2 NPT or, OptionalM20 or PG13 conduit adapter (see figure 4)Wire Size: 18 to 22 AWG

Mounting Position

Any position is acceptable for standard pipestand,panel, or actuator mounting. For weatherproofhousing, mount the transducer to allow the vent todrain.

Continued

APPROVED

ATEX

646 TransducersProduct Bulletin62.1:646April 2007

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Specifications (continued)Approximate Weight (Transducer Only)

1.6 kg (3.5 pounds)

Options

Output pressure gauge

1. Defined in ISA Standard S51.1.2. Normal m3/hour--Normal cubic meters per hour (0C and 1.01325 bar, absolute). Scfh--Standard cubic feet per hour (60F and 14.7 psig).3. Performance values are obtained using a transducer with a 4 to 20 mA dc input signal and a 0.2 to 1.0 bar (3 to 15 psig) output signal at an ambient temperature of 24C (75F).4. The pressure and temperature limits in this document and any applicable standard or code limitation should not be exceeded.

Table 1. Immunity PerformancePORT PHENOMENON BASIC STANDARD PERFORMANCE CRITERIA(1)

Enclosure

Electrostatic discharge (ESD) IEC 61000-4-2 A

EM field IEC 61000-4-3 A

Rated power frequency magnetic field IEC 61000-4-8 A

I/O signal/control

Burst IEC 61000-4-4 A

Surge IEC 61000-4-5 B

Conducted RF IEC 61000-4-6 A1. A = No degradation during testing. B = Temporary degradation during testing, but is self-recovering.Specification Limit = +/ 1% of span.

Table 2. Hazardous Area Classifications for CanadaCSACERTIFICATION

BODYCERTIFICATION OBTAINED ENTITY RATING TEMPERATURE CODE ENCLOSURE RATING

CSA

(Intrinsic Safety)Class/DivisionClass I, II Division 1 GP A, B, C, D, E, F, G per drawing21B5606

T4A (Tamb 71C) CSA ENC 3

(Explosion Proof)Class I, Division I, Groups A, B, C, D

T5 (Tamb 71C) CSA ENC 3

Class I, Division 2, GP A, B, C, DClass II, Division 1, Groups E, F, GClass II, Division 2, GP E, F, G

T5 (Tamb 71C) CSA ENC 3

Table 3. Hazardous Area Classifications for United StatedFMCERTIFICATION

BODYCERTIFICATION OBTAINED ENTITY RATING TEMPERATURE CODE ENCLOSURE RATING

FM

(Intrinsic Safety)Class I, II, III Division 1 GP A, B, C, D, E, F, G perdrawing 21B5607

Vmax = 40 VDCImax = 200 mACi = 0 nFLi = 0 mH

T5 (Tamb 60C) NEMA 3

(Explosion Proof)Class I, Division I, Groups A, B, C, D


Class I, Division 2, GP A, B, C, DClass II, Division 1, Groups E, F, GClass II, Division 2, GP F, G


Table 4. Hazardous Area ClassificationsATEXCERTIFICATE CERTIFICATION OBTAINED ENTITY RATING TEMPERATURE CODE ENCLOSURE RATING

ATEX

II 1 GGasEEx ia IIC T4/T5 Intrinsic Safety

Ui = 30 VDCIi = 150 mAPi = 1.0 WCi = 0 nFLi = 0 mH

T4 (Tamb 71C)

T5 (Tamb 40C)IP54

II 2 GGasEEx d IIB T6 Flameproof

T6 (Tamb 71C) IP54

II 3 GGasEEx nL IIC T6 Type n

T6 (Tamb 71C) IP54


62.1:646April 2007

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A6013/IL

6.8V 6.8V 6.8V 0.7V

0.7V

0.7V

60 Ohms

60 Ohms

23 Ohms

4 - 20 mA+

Figure 2. Equivalent Circuit

Features Small SizeThe small size and light-weight

design of the transducer facilitate mounting andprovide improved space utilization.

Vibration ResistanceThe transducer, usedin a standard valve/actuator mounted application,exhibits an output shift of less than 1 percent of spanwhen tested to SAMA Standard PMC 31.1,Condition 3.

High Output CapabilityThe output volumeof the transducer is adequate to drive valve/actuatorcombinations without requiring a positioner orvolume booster.

LOADING

EXHAUSTING

TIME (%)

0 10 20 30 40 50 60 70 80 90 1000

10

20

30

40

50

60

70

80

90

100

OU

TP

UT

(% O

F T

YP

E 6

46 O

UT

PU

T S

PAN

)

A6815 / IL

Figure 3. Output-Time Relationships for Type 646 Transducer

Low Air ConsumptionThe transducer haslow air consumption which cuts operating costs.

Easy MaintenanceModular design of theconverter allows easy replacement in the field forreduced maintenance costs.

Superior PerformanceThe accuracy,linearity, and frequency response coupled withminimal hysteresis far exceed the requirements ofmost control systems.

Mounting Position InsensitivityThe Type646 will operate in any orientation.

646 TransducersProduct Bulletin62.1:646April 2007

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35(1.38)

6.4(.25)

127.0(5.00)

72.8(2.86)

102.1(4.02)

152.4(6.00)

152.4(6.00)

79.2(3.12)

47.8(1.88)

41.1(1.62)

127.0(5.00)

9.5(.38)

9.7(.38)

mm(INCH)

CENTERLINEOF ACTUATOR

EXHAUST

1/4-18 NPT OPTIONAL OUTPUTOR GAUGE CONN

1/4-18 NPTOUTPUT CONN

1/2-14 NPTOR OPTIONALM20 CONDUIT CONN

OPTIONALGAUGE

TYPE 67CFR1/4-18 NPTSUPPLY CONN

CAP REMOVALCLEARANCE

57(2.25)

106.4(4.19)

62.0(2.44)

38B3958-AA6816-1 / IL

Figure 4. Dimensions

Valve Stroking TimeFigure 3 shows relative times for loading andexhausting an actuator. Stroking time depends uponthe size of the actuator, travel, relay characteristicsand the magnitude and rate of change of the inputsignal. If stroking time is critical, contact yourEmerson Process Management sales office.

InstallationRefer to figure 4 for location of standard mountingholes in the housing. Standard mounting hardware isprovided for mounting on the actuator, a pipestand,or a panel. Field wiring connections are made to theterminal block accessible under the housing cap.Dimensions are shown in figure 4.

Ordering Information

To determine what ordering information is required,refer to the specification table. Carefully review thedescription of each specification. Specify the desiredchoice whenever there is a selection available. Also,specify options that are applicable to the application.

Note

Neither Emerson, Emerson ProcessManagement, nor any of their affiliatedentities assumes responsibility for theselection, use, and maintenance of anyproduct. Responsibility for theselection, use, and maintenance of anyproduct remains with the purchaserand end-user.


62.1:646April 2007

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Emerson Process Management Marshalltown, Iowa 50158 USACernay 68700 France Sao Paulo 05424 BrazilSingapore 128461

Fisher Controls International LLC 1988, 2007; All Rights Reserved Printed in USA

www.Fisher.com

The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they arenot to be construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability.We reserve the right to modify or improve the designs or specifications of such products at any time without notice.

Neither Emerson, Emerson Process Management, nor any of their affiliated entities assumes responsibility for the selection, use and maintenance of any product. Responsibility for the selection, use and maintenance of any product remains with the purchaser and end-user.

Fisher is a mark owned by Fisher Controls International LLC, a member of the Emerson Process Management business division of Emerson Electric Co. Emerson Process Management, Emerson, and the Emerson logo are trademarks and service marks of Emerson Electric Co. All other marks are the property of their respective owners. This product may be covered under one or more of the following patents: 4,836,011 and4,595,029 or under pending patents.

type 646 electro-pneumatic

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