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56 回閲覧Set Pressure vs. Cold Differential Test Pressure — A Field Guide
set pressureCDTPback pressurebench test
The short answer
Cold differential test pressure (CDTP) compensates the bench set point for the temperature and back-pressure the valve will see in service.
Rules of thumb
- For conventional valves, add the superimposed back pressure to the desired set pressure.
- Correct for temperature when service exceeds 120 C, using the manufacturer chart.
- Balanced-bellows valves already negate most back-pressure effects — check the datasheet first.
Common mistakes
Applying CDTP to pilot-operated valves without checking the pilot dome rating, and forgetting that CDTP changes when the process conditions change.