Identify High and Low Ports on Pneumatic DP Transmitter

Identify the “high” and “low” ports on this pneumatic differential pressure transmitter, and explain your reasoning:

Pneumatic DP Transmitter

Also, explain how this transmitter will respond to an increasing pressure at each of its two ports, including the operation of the bellows feedback mechanism.

Answer:

Port “A” is the “high” pressure port on this transmitter, and port “B” is the “low” pressure port.

Remember: an increasing pressure applied to the “high” port causes an increasing signal out of the transmitter.

Conversely, an increasing pressure applied to the “low” port causes a decreasing signal out of the transmitter.

Note: These are very old models and obsolete now.

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