Temperature

①: Temperature suddenly increases This fault is often caused by an open circuit in the thermistor (thermocouple), loose wiring terminals, broken (compensating) wires, or temperature failure. At this time, it is necessary to understand the location and wiring layout of the temperature, and use the resistance (millivolt) gear of the multimeter to measure several sets of data at different locations to quickly find the cause.

　　 ②: Temperature suddenly decreases This fault is often caused by a short circuit in the thermocouple or thermistor, a short circuit in the wire, or temperature failure. Start from the wiring port, wire bends, and other weak points that are prone to failure, and check them one by one. If the on-site temperature rises but the central control indication remains unchanged, it is often caused by a liquid (water) with a lower boiling point at the measuring element.

　　 ③: The temperature fluctuates greatly or oscillates rapidly At this time, the process operation should be checked mainly (the regulating system involved in the regulation should be checked).

Pressure

①: Pressure suddenly decreases, increases, or the indication curve does not change At this time, the pressure transmitter's pressure introduction system should be checked, including whether the root valve is blocked, whether the pressure introduction pipe is unobstructed, whether there are abnormal media in the pressure introduction pipe, whether the drain wire is blocked, and whether the drain valve is leaking, etc. Freezing of the medium in winter is also a common phenomenon. The possibility of a fault in the transmitter itself is very small.

②: Large pressure fluctuations In this case, it is first necessary to cooperate with the process personnel. It is generally caused by improper operation. The parameters involved in the regulation should mainly check the regulation system.

Flow

①: The flow indication is minimal This is generally caused by the following reasons: damage to the detection element (the zero point is too low); display problems; short circuit or open circuit; positive pressure chamber blockage or leakage; low system pressure; parameters involved in regulation should also check the regulator, regulating valve, and solenoid valve.

②: The flow indication is maximal The main reason is that the negative pressure chamber pressure introduction system is blocked or leaking. The transmitter is unlikely to need calibration.

③: Large flow fluctuations If the flow parameters are not involved in regulation, it is generally due to process reasons; if they are involved in regulation, the PID parameters of the regulator can be checked; for parameters with isolation tanks, check whether there are bubbles in the pressure introduction pipe and whether the liquid in the positive and negative pressure introduction pipes is at the same height.

Level

①: Level suddenly increases Mainly check whether the negative pressure chamber pressure introduction system of the transmitter is blocked, leaking, accumulating gas, or lacking liquid, etc. The specific method of filling liquid is: stop the meter according to the stop meter sequence; close the positive and negative pressure root valves; open the positive and negative pressure drain valves to relieve pressure; open the double-chamber equilibrium container filling liquid wire plug; open the positive and negative pressure chamber drain wire plugs; at this time, the level indication is maximal. Close the drain valve; close the positive and negative pressure chamber drain wire plugs; slowly fill the double-chamber equilibrium container with the same medium; at this time, slightly open the drain wire plug to vent; until it is full, at this time, open the positive pressure chamber wire plug, and the transmitter indication should return to zero. Then, put the transmitter into use according to the start-up sequence.

　　 ②: Level suddenly decreases Mainly check whether the positive pressure chamber pressure introduction system is blocked, leaking, accumulating gas, lacking liquid, or whether the balance valve is completely closed, etc. The specific method to check whether the pressure introduction system is unobstructed is to stop the transmitter, open the drain valve, and check the drainage situation (except for media that cannot leak externally).

　　 ③: The central control room indication does not match the on-site level First, determine whether the on-site level meter is malfunctioning. At this time, the level can be artificially increased or decreased, and the problem cause can be specifically analyzed based on the on-site and central control indications (the on-site level meter root valve is closed, blocked, or leaking easily causes inaccurate on-site indication). The level can be restored to normal by checking the zero point, range, and filling liquid. If it is still abnormal, the process personnel can be notified to supervise the on-site dismantling and calibration of the transmitter.

　　 ④: Frequent level fluctuations First, cooperate with the process personnel to check the feeding and discharging situation. After confirming that the process condition is normal, the stability can be achieved by adjusting the PID parameters. The specific method is: put the regulating valve into manual state, first adjust the set value to be consistent with the measured value, so that the level fluctuation becomes stable, then slowly adjust the regulating valve opening, so that the level slowly rises or falls to meet the process requirements, then adjust the set value to be consistent with the measured value, and after the parameters are stable, put the regulating valve into automatic state.