Emerson Fisher 646 User manual

www.Fisher.com
Fisherr646 Electro‐Pneumatic Transducer
Contents
Introduction 1.................................
Scope of Manual 1.............................
Description 3.................................
Specifications 4...............................
Educational Services 4.........................
Installation 4..................................
Hazardous Area Classifications and
Special Instructions for “Safe Use” and
Installation in Hazardous Locations 5...........
CSA 5....................................
FM 6.....................................
ATEX 6...................................
IECEx 7...................................
Mounting 8..................................
Pneumatic Connections 9......................
Supply Pressure Requirements 9.............
Diagnostic Connections 10..................
Vent 10..................................
Electrical Connections 10.......................
Operating Information 12........................
Calibration 12................................
Equipment Required 12.....................
Calibration Procedure 12....................
Principle of Operation 13........................
Maintenance 14................................
Troubleshooting 14............................
Converter Module Replacement 15..............
Relay Maintenance 16..........................
Figure 1. Fisher 646 Electro‐Pneumatic Transducer
Mounted on a Sliding‐Stem Actuator
W6783‐1/IL
Parts Ordering 18...............................
Parts Kits 18...................................
Parts List 18...................................
Loop Schematics 22.............................
Introduction
Scope of Manual
This instruction manual provides installation, operation, maintenance, and parts ordering information for the Fisher
646 transducer. Refer to separate manuals for instructions covering equipment used with the transducer.
Do not install, operate or maintain a 646 electro‐pneumatic transducer without being fully trained and qualified in
valve, actuator and accessory installation, operation and maintenance. To avoid personal injury or property damage it
is important to carefully read, understand, and follow all of the contents of this manual, including all safety cautions
and warnings. If you have any questions about these instructions, contact your Emerson Process Management sales
office before proceeding.
Instruction Manual
D101351X012
646 Transducer
January 2015

Instruction Manual
D101351X012
646 Transducer
January 2015
2
Table 1. Specifications
Input Signal
4-20 mA DC, constant current with 30 VDC maximum
compliance voltage
Equivalent Circuit
The 646 equivalent circuit is a series circuit consisting
of a constant voltage drop (battery) of approximately
2.1 VDC and a total resistance of 143 ohms. Input is
shunted by three 6.8 V zener diodes (see figure 6).
Output Signal
0.2 to 1.0 bar (3 to 15 psig) direct acting only
Supply Pressure(1)
Recommended: 1.4 bar (20 psig)
Minimum: 1.4 bar (20 psig)
Maximum: 3.4 bar (50 psig)
Average Steady‐State Air Consumption(2)(3)
0.08 m3/hr (3 scfh) at 1.4 bar (20 psi) supply pressure
Maximum Output Air Capacity(2)
8.0 m3/hr (300 scfh) at 1.4 bar (20 psig) supply
pressure
Performance(4)
Reference Accuracy: ±0.5% of full scale output span;
includes combined effects of hysteresis, linearity, and
deadband
Independent Linearity: ±0.5% of full scale output span
Hysteresis: 0.4% of full scale output span
Frequency Response: Gain is attenuated 3 dB at 10 Hz
with transducer output signal piped to a typical
instrument input
Temperature Effect: ±4% of full scale output span per
55_C (100_F) change
Supply Pressure Effect: 0.2% of full scale output span
per psi supply pressure change
Vibration Effect: Less than 1% of full scale output span
when tested to SAMA PMC 31.1, Condition 3
Electromagnetic Compatibility
Meets EN 61326‐1 (First Edition)
Immunity—Industrial locations per Table 2 of
the EN 61326‐1 standard. Performance is
shown in table 2 below.
Emissions—Class A
ISM equipment rating: Group 1, Class A
Operating Ambient Temperature Limits(1)
-40 to 71_C (-40 to +160_F)
Electrical Classification
CSA—Intrinsically Safe, Explosion proof, Type n,
Dust‐Ignition proof, DIV 2
FM—Intrinsically Safe, Explosion proof, Type n,
Non‐incendive, Dust‐Ignition proof
ATEX—Intrinsically Safe, Flameproof, Type n
IECEx—Intrinsically Safe, Flameproof, Type n
Refer to Hazardous Area Classifications and Special
Instructions for the “Safe Use” and Installation in
Hazardous Locations starting on page 5 for
additional information.
Housing
CSA—Type 3 Encl.
FM—NEMA 3, IP54
ATEX—IP64
IECEx—IP54
Mount instrument with vent on side or bottom if
weatherproofing is a concern.
Other Classifications/Certifications
INMETRO— National Institute of Metrology, Quality
and Technology (Brazil)
KGS— Korea Gas Safety Corporation (South Korea)
Contact your Emerson Process Management sales
office for classification/certification specific
information
Connections
Supply and Output Pressure: 1/4 NPT internal
connection
Vent: 1/4 NPT internal
Electrical: 1/2‐14 NPT conduit connection
Wire Size: 18 to 22 AWG
Adjustments
Zero and Span: Trim potentiometers (20 turn) for
zero and span adjustments are located under the
housing cap (see figure 7)
-continued-

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Table 1. Specifications (Continued)
Mounting Position
Any position is acceptable for standard pipestand,
panel, or actuator mounting. For weatherproof
housing, mount the transducer so the vent can drain.
Approximate Weight (Transducer Only)
1.6 kg (3.5 pounds)
Actuator Stroking Time
See figure 2
Declaration of SEP
Fisher Controls International LLC declares this
product to be in compliance with Article 3 paragraph
3 of the Pressure Equipment Directive (PED) 97 / 23 /
EC. It was designed and manufactured in accordance
with Sound Engineering Practice (SEP) and cannot
bear the CE marking related to PED compliance.
However, the product may bear the CE marking to
indicate compliance with other applicable European
Community Directives.
NOTE: Specialized instrument terms are defined in ANSI/ISA Standard 51.1 ‐ Process Instrument Terminology.
1. The pressure and temperature limits in this document and any applicable standard or code limitation should not be exceeded.
2. Normal m3/hr—Normal cubic meters per hour (0_C and 1.01325 bar, absolute). Scfh—Standard cubic feet per hour (60_F and 14.7 psia).
3. Average flow rate determined at 12 mA and 0.6 bar (9 psig) output.
4. Performance values are obtained using a transducer with a 4 to 20 mA DC input signal and a 0.2 to 1.0 ba (r3 to 15 psig) output signal at an ambient temperature of 24_C (75_F).
Table 2. EMC Summary Results—Immunity
Port Phenomenon Basic Standard Test Level Performance
Criteria(1)
Enclosure
Electrostatic discharge (ESD) IEC 61000‐4‐2 4 kV contact
8 kV air A
Radiated EM field IEC 61000‐4‐3
80 to 1000 MHz @ 10V/m with 1 kHz AM at 80%
1400 to 2000 MHz @ 3V/m with 1 kHz AM at 80%
2000 to 2700 MHz @ 1V/m with 1 kHz AM at 80%
A
I/O signal/control
Burst (fast transients) IEC 61000‐4‐4 1 kV A
Surge IEC 61000‐4‐5 1 kV (line to ground only, each) B
Conducted RF IEC 61000‐4‐6 150 kHz to 80 MHz at 3 Vrms A
1. A = No degradation during testing. B = Temporary degradation during testing, but is self‐recovering.
Specification Limit = +/‐ 1% of span.
Figure 2. Output‐Time Relationships for Fisher 646 Transducer
LOADING
EXHAUSTING
TIME (%)
0 102030405060708090100
0
10
20
30
40
50
60
70
80
90
100
OUTPUT
(% OF 646 OUTPUT SPAN)
A6815 / IL
Description
The transducer, shown in figure 1, receives a 4-20 milliampere DC input signal and transmits a proportional 0.2 to 1.0
bar (3 to 15 psig) pneumatic output pressure to a final control element. A typical application is in electronic control
loops where the final control element is a control valve assembly that is pneumatically operated. The input signal and
output pressure range of the transducer is indicated on the nameplate attached to the housing.

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CAUTION
Dropping or rough handling of the transducer can cause damage to the converter module resulting in a shifted output or a
minimum output.
WARNING
This product does not meet third party approvals (CSA, FM, ATEX, or IECEx) for use with natural gas as the supply medium.
Use of natural gas as the supply medium can damage the instrument and result in personal injury or property damage from
fire or explosion.
Should you need an instrument for use with natural gas, Fisher 846 and i2P‐100 electro‐pneumatic transducers both meet
third party approvals for use with natural gas as the supply medium. Contact your Emerson Process Management sales
office for information on these products.
Specifications
Specifications for the 646 transducer are listed in table 1.
Educational Services
For information on available courses for the 646 electro‐pneumatic transducer, as well as a variety of other products,
contact:
Emerson Process Management
Educational Services, Registration
Phone: +1-641‐754‐3771 or +1-800‐338‐8158
e‐mail: [email protected]
http://www.emersonprocess.com/education
Installation
WARNING
Always wear protective clothing, gloves, and eyewear when performing any installation operations to avoid personal
injury.
Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.
If installing into an existing application, also refer to the WARNING at the beginning of the Maintenance section in this
instruction manual.

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Hazardous Area Classifications and Special Instructions for “Safe Use” and
Installation in Hazardous Locations
Certain nameplates may carry more than one approval, and each approval may have unique installation/wiring
requirements and/or conditions of “safe use”. These special instructions for “safe use” are in addition to, and may
override, the standard installation procedures. Special instructions are listed by approval.
Note
This information supplements the nameplate markings affixed to the product.
Always refer to the nameplate itself to identify the appropriate certification. Contact your Emerson Process Management sales
office for approval/certification information not listed here.
WARNING
Failure to follow these conditions of “safe use” could result in personal injury or property damage from fire or explosion
and area re‐classification.
CSA
Intrinsically Safe, Explosion proof, Type n Dust‐Ignition proof, DIV 2
No special conditions for safe use.
Refer to table 3 for additional information.
Table 3. Hazardous Area Classifications—CSA (Canada)
Certification Body Certification Obtained Entity Rating Temperature Code
CSA
Intrinsically Safe
Ex ia IIC T4/T5 per drawing GE28591 (see figure 12)
Ex ia Intrinsically Safe
Class I, II, Division 1 GP A,B,C,D,E,F,G T4/T5
per drawing GE28591 (see figure 12)
Vmax = 30 VDC
Imax = 150 mA
Pi = 1.0 W
Ci = 0 nF
Li = 0 mH
T4 (Tamb ≤71°C)
T5 (Tamb ≤40°C)
Explosion-proof
Ex d IIC T6
Class I, Division I, GP A,B,C,D T6
- - - T6 (Tamb ≤71°C)
Type n
Ex nL IIC T6 - - - T6 (Tamb ≤71°C)
Class I, Division 2, GP A,B,C,D T6
Class II, Division 1, Groups E,F,G T6
Class II, Division 2, GP F,G T6
- - - T6 (Tamb ≤71°C)

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FM
Intrinsically Safe, Explosion proof, Type n Non‐incendive, Dust‐Ignition proof
No special conditions for safe use.
Refer to table 4 for additional information.
Table 4. Hazardous Area Classifications—FM (United States)
Certification Body Certification Obtained Entity Rating Temperature Code
FM
Intrinsically Safe
Class 1 Zone 0 AEx ia IIC T4/T5
per drawing GE28590 (see figure 13)
Class I, II, III Division 1 GP A,B,C,D,E,F,G
T4/T5 per drawing GE28590 (see figure 13)
Vmax = 30 VDC
Imax = 150 mA
Pi = 1.0 W
Ci = 0 nF
Li = 0 mH
T4 (Tamb ≤71°C)
T5 (Tamb ≤40°C)
Explosion-proof
Class 1 Zone 1 AEx d IIC T6
Class I, Division I, GP A,B,C,D T6
- - - T6 (Tamb ≤71°C)
Type n
CL 1 Zone 2 AEx nL IIC T6 - - - T6 (Tamb ≤71°C)
Class I, Division 2, GP A,B,C,D T6
Class II, Division 1, Groups E,F,G T6
Class II, Division 2, GP F,G T6
- - - T6 (Tamb ≤71°C)
ATEX
Standards Used for Certification
EN 60079-0: 2012 EN 60079-31: 2009
EN 60079-1: 2007 EN 61241-0: 2006
EN 60079-11: 2012 EN 61241-1: 2004
EN 60079-15: 2010 EN 61241-11: 2006
Special Conditions for Safe Use
Intrinsically Safe
This equipment is intrinsically safe and can be used in potentially explosive atmospheres.
The electrical parameters of certified equipment which can be connected to the device must not exceed the following
values: U0≤30 VDC ; I0≤150 mA ; P0≤1 W
Ambient temperature: T5, at Tamb = 40_C ; T4, at Tamb = 71_C
Flameproof
The flame path is other than required by EN 60079‐1. Contact the manufacturer for information on the dimensions of
the flameproof joints.
Electrical connections are typically made using either cable or conduit.
D If using a cable connection, the cable entry device shall be certified in type of explosion protection flameproof
enclosure “d”, suitable for the conditions of use and correctly installed.
For ambient temperatures over 70_C, cables and cable glands suitable for at least 90_C shall be used.

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D If using a rigid conduit connection, an Ex d certified sealing device such as a conduit seal with setting compound
shall be provided immediately to the entrance of the enclosure.
For ambient temperatures over 70_C, the wiring and setting compound in the conduit seal shall be suitable for at least
90_C.
Type n
No special conditions for safe use.
Refer to table 5 for additional information.
Table 5. Hazardous Area Classifications—ATEX
Certificate Certification Obtained Entity Rating Temperature Code
ATEX
II 1 G & D
Intrinsically Safe
Gas
Ex ia IIC T4/T5 Ga
Ui = 30 VDC
Ii = 150 mA
Pi = 1.0 W
Ci = 0 nF
Li = 0 mH
T4 (Tamb ≤71°C)
T5 (Tamb ≤40°C)
Dust
Ex ia IIIC Da T155 °C (Tamb ≤71°C) / T124°C (Tamb ≤40°C) - - -
II 2 G & D
Flameproof
Gas
Ex d IIC T6 Gb - - -
T6 (Tamb ≤71°C)
Dust
Ex tb IIIC T74 °C Db (Tamb ≤71°C) - - -
II 3 G & D
Type n
Gas
Ex nA IIC T6 Gc - - -
T6 (Tamb ≤71°C)
Dust
Ex tc IIIC T74 °C Dc (Tamb ≤71°C) - - -
IECEx
Conditions of Certification
Intrinsically Safe
WARNING
Substitution of components may impair intrinsic safety.
-40_C ≤Ta ≤+71_C ; T5 (Ta ≤+40_C) ; T4 (Ta ≤+71_C)
Entity Parameters: Ui=30 V , li = 150 mA , Pi = 1.0 W , Ci = 0 nF , Li = 0 mH
Flameproof
WARNING
Disconnect power before opening.
-40_C ≤Ta ≤+71_C ; T6 (Ta ≤+71_C)

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Type n
WARNING
Disconnect power before opening.
-40_C ≤Ta ≤+71_C ; T6 (Ta ≤+71_C)
Refer to table 6 for additional information.
Table 6. Hazardous Area Classifications—IECEx
Certificate Certification Obtained Entity Rating Temperature Code
IECEx
Intrinsically Safe
Gas
Ex ia IIC T4/T5 Ga
Ui = 30 VDC
Ii = 150 mA
Pi = 1.0 W
Ci = 0 nF
Li = 0 mH
T4 (Tamb ≤71°C)
T5 (Tamb ≤40°C)
Flameproof
Gas
Ex d IIC T6 Gb
- - - T6 (Tamb ≤71°C)
Type n
Gas
Ex nA IIC T6 Gc
- - - T6 (Tamb ≤71°C)
Mounting
When a transducer is ordered as part of a control valve assembly, the factory mounts the transducer on the actuator
and connects the necessary tubing, then adjusts the transducer as specified on the order.
Transducers also can be ordered separately for mounting on a control valve assembly already in service, or for
mounting on a 2 inch diameter pipestand, a flat surface, or a bulkhead. The transducer may be ordered either with or
without mounting parts. Mounting parts include a mounting plate and bolts and, if ordered for pipestand mounting, a
pipe clamp. Tubing is not included if the transducer is not factory mounted. Use 10 mm (3/8‐inch) diameter tubing for
all input and output connections. The length of tubing between the transducer output and the final control element
should be as short as possible. Transducer overall dimensions are shown in figure 3. If weatherproofing is required,
mount the transducer so that the vent can drain. Do not allow moisture or condensate to collect in the vent.

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Figure 3. Dimensions and Connections
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)
127.0
(5.00)
9.5
(.38)
9.7
(0.38)
mm
(INCH)
CENTERLINE
OF ACTUATOR
EXHAUST
1/4‐18 NPT
OPTIONAL OUTPUT
OR GAUGE CONN
1/4‐18 NPT
OUTPUT CONN
1/2‐14 NPT
CONDUIT CONN
OPTIONAL
GAUGE
67CFR
1/4‐18 NPT
SUPPLY
CONN
CAP
REMOVAL
CLEARANCE
57
(2.25)
106.4
(4.19)
62.0
(2.44)
38B3958‐A
A6816‐1 / IL
41.1
(1.62)
Pneumatic Connections
As shown in figure 3, all pressure connections on the transducer are 1/4 NPT internal connections. Use 10 mm
(3/8‐inch) tubing for all pressure connections. Refer to the vent subsection below for remote vent connections.
Supply Pressure Requirements
WARNING
Severe personal injury or property damage may occur if the instrument air supply is not clean, dry and oil‐free. While use
and regular maintenance of a filter that removes particles larger than 40 micrometers in diameter will suffice in most
applications, check with an Emerson Process Management field office and industry instrument air quality standards for use
with corrosive air or if you are unsure about the proper amount or method of air filtration or filter maintenance.
Supply pressure must be clean, dry air. Use a Fisher 67CFR filter regulator with standard 5 micrometer filter, or
equivalent, to filter and regulate supply air. The filter regulator can be mounted on a bracket with the transducer as
shown in figure 11 or mounted on the actuator mounting boss. An output pressure gauge may be installed on the
regulator to indicate the supply pressure to the transducer. Also, as an aid for calibration, a second gauge may be
installed on the transducer to indicate transducer output pressure.

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Connect the nearest suitable supply source to the 1/4 NPT IN connection on the filter regulator (if furnished) or to the
1/4 NPT SUPPLY connection on the transducer case (if the filter regulator is not attached).
Diagnostic Connections
To support diagnostic testing of valve/actuator/positioner packages, special connectors and hardware are available.
Typical connector installations are shown in figure 4. The hardware used includes a 1/4 NPT pipe nipple and pipe tee
with a 1/8 NPT pipe bushing for the connector. The connector consists of a 1/8 NPT body and body protector.
Figure 4. Diagnostics Hookup for the Fisher 646 Transducer
BODY
BODY PROTECTOR
PIPE BUSHING
BODY PROTECTOR
BODY
PIPE BUSHING
PIPE TEE
PIPE NIPPLE
GAUGE
STEM
PROVIDED WHEN
GAUGE IS SPECIFIED
SIDE OUTPUTFRONT OUTPUT
12B8040‐A
B2395‐1/IL
Note
If the 646 transducer is used in a valve assembly with a positioner, no hook‐up for diagnostic testing is required for the 646. The
hook‐up for diagnostic testing should be installed at the positioner.
Install the connectors and hardware between the 646 transducer and the actuator.
1. Before assembling the pipe nipple, pipe tee, pipe bushings, actuator piping, and connector body, apply sealant to
all threads.
2. Turn the pipe tee to position the connector body and body protector for easy access when doing diagnostic testing.
Vent
If a remote vent is required, the vent line must be as short as possible with a minimum number of bends and elbows.
To connect a remote vent, remove the plastic vent (key 41, figure 10). The vent connection is 1/4 NPT internal. Use
3/8‐inch tubing to provide a remote vent.
Electrical Connections
WARNING
For explosion‐proof applications, disconnect power before removing the housing cap.