Pressure measuring instrument fault inspection

　　Pressure instruments installed locally are mostly bourdon tube pressure gauges, capsule micro pressure gauges, etc. These types of pressure gauges have obvious faults. By observing how large they are, problems can be identified and can be replaced or repaired as appropriate. Blockage and leakage of pressure pipes or sampling valves are common faults. The fault manifestations of the pressure transmitter include: no output, deviation of zero point, high or low output, output fluctuation, and other phenomena. The output of the resistance type remote pressure gauge is a resistance signal, and the fault manifestations are: open circuit, open circuit, poor contact, causing the display instrument to have no indication, low indication, fluctuating indication, and other faults.            

        Pressure parameters have the characteristics of small time constants and rapid changes, which can help us determine whether it is a process cause or an instrument failure. Common faults and possible causes of pressure instruments are as follows. 

       1.The sudden drop of the pressure display value to zero, or a large indication, is a malfunction of the instrument. It is impossible for the process pressure to suddenly drop to zero or suddenly increase. "The pressure fluctuates significantly but changes slowly. It is important to first identify process reasons, such as changes in load, feeding, reflux, temperature, and process conditions, or improper process operation, which can cause changes in process pressure.".  

        2. The pressure control system has a large fluctuation in the pressure curve and is in a fast oscillating state. First, observe whether the pressure parameters really fluctuate, switch the system to manual operation, and observe the changes in the pressure curve to determine the fault. For new systems, it is necessary to check the parameter setting of the regulator and whether there is oscillation in the regulating valve.

       3. During daily maintenance, it is necessary to understand the process and be aware of the fluctuations in process pressure, so as to distinguish between instrument anomalies and process fluctuations. When judging faults, you can refer to other process parameters to make a more accurate judgment of pressure fluctuations.