Instrument of temperature, pressure, flow, liquid level failure analysis and measurement

by:J&T     2020-07-01
Meter is typically used in pressure vessel, gas and liquid pipelines, temperature and flow rate measurement, many use situations, using environment is different, the use of instrument equipment if instrument malfunction is very troublesome, is has certain influence to production and equipment use, so what are common instrument faults, in the face of the instrument temperature, pressure, flow, liquid level of fault analysis; A, pressure instrumentation system common fault and analysis of 1, suddenly become smaller, bigger or instruction curve: there is no change at this time should check the transducer pressure system, check whether the root valve jams, lead the pressure pipe was clear, whether there are abnormal medium inside pressure tube, whether the drain plug and drain valve leakage, etc. Frozen winter media is also a common phenomenon. The transmitter itself fault possibility is very small. 2, large pressure fluctuation: this situation must first combine with technology personnel, is usually caused by improper operation. Check the main control system involved in regulating the parameters. Second, liquid level instrumentation system common fault and analysis of 1, liquid level suddenly become bigger: mainly check the transducer pressure chamber pressure system is blocked, leakage, gas collection, such as lack of fluid. Priming the specific method is: according to the stop watch to stop watch order; Closed pressure root valve; Open the pressure drain valve pressure relief; Open the double chamber balance container priming plug; Open the pressure chamber drain plug; The level indicator is the largest. Close the drain valve; Close is negative pressure chamber drain plug. Using the same medium to slow down the double chamber balance container, slightly open at this time the drain plug exhaust; Until filled, open the positive pressure chamber plug, transmitter indication should be back to zero. Then according to the table order putting-in-service proactively transmitter. Level 2, suddenly become smaller: the main check whether positive pressure chamber pressure system led wall, leakage, gas collection, lack of liquid, the balance valve is shut up, etc. Check led the pressure system was clear the specific method is to stop transducer, open the drain valve, check the blowdown circumstance ( Can't leaked except medium) 。 3, control rooms instructions is inconsistent with the liquid level: first determines whether the liquid level meter, at this time can be artificially increase or reduce the liquid level, according to the situation and general control instructions specific to analyse the reason of problem ( Field level gauge roots outside the valve closed, jam, easy cause leakage field indicates no) 。 Can check the zero point, range, liquid filling and liquid level to return to normal. If you still not normal, can inform technology personnel on-site monitoring back down the transmitter on the set-up. 4, frequent fluctuations of liquid level: first combined with inspection incoming material and technological personnel, the discharging situation, determine the process conditions after normal, can be stable by adjusting PID parameters. Specific method is: the regulator pitching motion state, to adjust the set value is consistent with the measured value, make the liquid level fluctuation calm down, then slowly adjust the valve opening, slow level rising or falling, meet the process requirements, and then adjust the set value is consistent with the measured value, after waiting for parameter stability regulator automatically. Three common fault analysis, temperature instrument system 1, the temperature suddenly increases, the fault is thermal resistance (more Thermocouple) Break loose, terminal, Compensation) Wire broken, such as temperature failure causes, you need to know the location of the temperature and wiring layout, use multimeter resistance ( Millivolts) File in a different position measured several groups of data can quickly find out the reason. 2, the temperature suddenly decrease: the fault for the thermocouple or heat resistance failure caused by short circuit, wire short circuit and temperature. From the wiring, wire bend easily the vulnerabilities of out of order, one by one. The scene temperature, and general control instructions is changeless, much as the measuring element place has a low boiling point liquid ( Water) Caused by. 3, temperature volatility or fast shock: at this time should be the main check the process operating conditions ( Involved in regulating the examination control system) 。 Four, flow meter system common fault and analysis of 1, minimum value flow indicator: generally caused by the following reasons: detecting element damage ( The zero point is too low. ; Show that there is a problem; Short circuit or open circuit; Positive pressure chamber wall or leakage; The system pressure is low; Participate in regulating parameters also check regulator, regulating valve and solenoid valve. 2, flow indicator: the main reason is that the negative pressure chamber pressure system blocked or leakage. Transmitter may not need adjustments. 3, flow volatility: flow parameter is not involved in the regulation, for technology reason commonly; Involved in the regulation, can check controller PID parameters; With the parameters of the isolation tank, to check whether there is bubble led the pressure tube, pressure is as high as the fluid pressure tube.
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