Instruction Manual
D101351X012
646 Transducer
January 2015
14
Maintenance
The normal mode of operation for the 646 transducer requires that the pneumatic output pressure be piped to the
final control element. If this is not done the resulting pneumatic output will vent to the atmosphere.
Due to normal wear or damage from external sources such as debris in the supply medium, periodic maintenance or
repair of the transducer may be necessary. Maintenance of the transducer consists of troubleshooting, removal for
inspection, and replacement of component parts.
WARNING
To avoid personal injury or property damage from the sudden release of pressure:
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Always wear protective clothing, gloves, and eyewear when performing any maintenance operations.
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Do not remove the actuator from the valve while the valve is still pressurized.
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Disconnect any operating lines providing air pressure, electric power, or a control signal to the actuator. Be sure the
actuator cannot suddenly open or close the valve.
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Use bypass valves or completely shut off the process to isolate the valve from process pressure. Relieve process pressure
on both sides of the valve.
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Use lock‐out procedures to be sure that the above measures stay in effect while you work on the equipment.
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Do not open when an explosive dust atmosphere is present.
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Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.
WARNING
For explosion proof applications, disconnect power before removing the housing cap. Personal injury or property damage
may result if power is not disconnected.
WARNING
The presence of Emerson Process Management personnel and approval agency personnel may be required if you service
(other than normal, routine maintenance, such as calibration) or replace components on a 646 transducer that carries a
third‐party approval. When you replace components, use only components specified by the factory. Substitution with
other components may void the third‐party approval and result in personal injury or property damage. Also, always use
proper component replacement techniques, as presented in this manual. Improper techniques can cause poor quality
repairs and impair the safety features of the device.
The converter module should never be disassembled because the magnetism in the coils will decrease permanently. If
troubleshooting or alignment attempts indicate a faulty converter module, replace the module or return the transducer to
your Emerson Process Management sales office for repair.
Troubleshooting
The following procedures require taking the control valve/actuator assembly out of service. Provide some temporary
means of process control before taking the control valve out of service.