Instruction Manual Fisher™ 646 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 Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Pneumatic Connections . . . . . . . . . . . . . . . . . . . . . . 5 Supply Pressure Requirements . . . . . . . . . . . . . 6 Diagnostic Connections . . . . . . . . . . . . . . . . . . . 7 Vent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . . 7 Operating Information . . . . . . . . . . . . . . . . . . . . . . . . . 9 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Equipment Required . . . . . . . . . . . . . . . . . . . . . . 9 Calibration Procedure . . . . . . . . . . . . . . . . . . . . . 9 Principle of Operation . . . . . . . . . . . . . . . . . . . . . . . . 10 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Converter Module Replacement . . . . . . . . . . . . . . 12 Relay Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Parts Ordering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Parts Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 1. Fisher 646 Electro‐Pneumatic Transducer Mounted on a Sliding‐Stem Actuator 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 Table 1. Specifications Input Signal Operating Ambient Temperature Limits(1) 4-20 mA DC, constant current with 30 VDC maximum compliance voltage Equivalent Circuit CSA—Intrinsically Safe, Explosion proof, Type n, Dust‐Ignition proof, DIV 2 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). FM—Intrinsically Safe, Explosion proof, Type n, Non‐incendive, Dust‐Ignition proof ATEX—Intrinsically Safe, Flameproof, Type...

Instruction Manual Table 1. Specifications (Continued) Declaration of SEP Mounting Position Any position is acceptable for standard pipestand, panel, or actuator mounting. For weatherproof housing, mount the transducer so the vent can drain. Fisher Controls International LLC declares this product to be in compliance with Article 4 paragraph 3 of the PED Directive 2014/68/EU. It was designed and manufactured in accordance with Sound Engineering Practice (SEP) and cannot bear the CE marking related to PED compliance. Approximate Weight (Transducer Only) 1.6 kg (3.5 pounds) However, the product...

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....

Hazardous Area Classifications and Special Instructions for “Safe Use” and Installation in Hazardous Locations Refer to the following instruction manual supplements for approval information. D CSA Hazardous Area Approvals Fisher 646 Electro-Pneumatic Transducer (D104199X012) D FM Hazardous Area Approvals Fisher 646 Electro-Pneumatic Transducer (D104200X012) D ATEX Hazardous Area Approvals Fisher 646 Electro-Pneumatic Transducer (D104201X012) D IECEx Hazardous Area Approvals Fisher 646 Electro-Pneumatic Transducer (D104202X012) All documents are available from your Emerson Process Management sales...

Instruction Manual Figure 3. Dimensions and Connections 152.4 (6.00) OPTIONAL GAUGE 1/4‐18 NPT OPTIONAL OUTPUT OR GAUGE CONN 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...

Instruction Manual 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 STEM PROVIDED WHEN GAUGE IS SPECIFIED BODY PROTECTOR BODY BODY PROTECTOR PIPE BUSHING PIPE BUSHING FRONT OUTPUT SIDE OUTPUT PIPE NIPPLE Note If the 646 transducer...