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The Field Performance Inspection of Control Valves
Control valves possess many performance criteria, and the follows should be paid more attention to for testing and adjustment:
1）Input the signal into the air chamber with smooth increase or decrease the signal between 20-100kPa, and measure the travel value corresponding to each point, to measure the difference between the actual and conceptual values of “signal – travel” at each point. The largest value is the basic difference. Test points should be five at 0%, 25%, 50%, 75%, and 100%, and the basic difference of the measuring instrument should be limited to 1/4 of the basic difference of the valve to be tested.
2) Return difference: the experimental method is the same. The return difference is that the maximum difference tested from a same signal.
3) Initial-terminal difference: the experimental method is the same. The basic difference at an initial point of the signal is the initial difference; the basic difference at the terminal point is the terminal difference.
4) Leakage test: the test medium is usually ambient temperature water. When the differential pressure is less than 350kPa, the experimental pressure is 350kPa; when the differential pressure is greater than 350kPa, it should be carried out with the allowable differential pressure. The experiment medium flows into a valve body in a predetermined direction, and the port can be directly connected with atmosphere or low-pressure testing equipment whose outlet is connected with atmosphere. It’s right time to test the leakage rate when the valve and
connecting tubes are full of medium. And the main valve should be tested in high pressure.The valve with a locator should be site tested before installation and operation.
Related recommendation:
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