Pakarab fertilizers limited multan

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Field Instrumentation

94 Field Instrumentation GEN Rev) 5. TRANSMITTERS

Draining sensing lines

As mentioned previously, the lines must be drained to remove any debris or particulate that may settle to the bottom of the tank and in the line. Also, in closed tank dry leg systems, condensate must be removed regularly to prevent fluid pressure building upon the low-pressure impulse line. Failure to do so will of course give a low tank level reading. Procedural care must be exercised to ensure the DP cell is not over-ranged inadvertently during draining. Such could happen if the block valves are not closed and equalizing

93 Field Instrumentation GEN Rev) valve opened beforehand. False high level indication can be caused by a leaking or drained wet leg. A leaking variable (process) leg can cause false low-level indication.

94 Field Instrumentation GEN Rev)

5. TRANSMITTERS

OBJECTIVES:

Upon Completion of this topic one should be able to understand

1. Function of transmitters
2. Types of transmitters
3. Pneumatic transmitter and its applications
4. Electronic transmitter and its applications
5. How to take transmitter into and out of service

95 Field Instrumentation GEN Rev)

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