Temperature instrument fault analysis
Symptom: The temperature indication is abnormal, high or low, or the change is slow or even unchanged.
Taking the thermal resistance as an example, first of all, we must understand the process situation, ask the process personnel to test the condition of the medium, whether it is normal medium or other medium such as test water, whether it is normal working condition. If it is not a newly installed thermal resistance, the possibility of reverse polarity of the line can be ruled out. After eliminating the above reasons, judge and check according to the idea of the figure.
Temperature meter fault analysis diagram (Y means yes; N means no)
Pressure instrument fault analysis
Symptom: A pump outlet indication is abnormal, high or low, or the indication is zero or does not change.
Take the electric pressure transmitter as an example (3051C). First of all, we should know whether the measured medium is gas or liquid, understand the process driving situation and simple process flow, and judge and handle the instrument fault according to the understanding of the process conditions and the instrument failure phenomenon. The fault diagnosis and processing can be checked according to the idea of the figure.
Pressure meter fault analysis diagram (Y means yes; N means no)
Flow instruments fault analysis
Symptom: The flow indication is abnormal, high or low, or the indication is zero, indicating fluctuation.
Take the differential pressure flow transmitter as an example (orifice flowmeter). When the instrument maintenance personnel handle the fault, they should know the situation to the process operator and understand the process conditions, such as the condition of the measured medium, the pump condition and the process flow. Through detailed understanding of the process driving situation, the fault handling can be judged and checked according to the idea shown in the figure.
Flow meter fault resolution diagram (Y means yes; N means no)
Level instrument fault analysis
Symptom: The liquid level indication will not change, high or low, or no indication.
The double flange liquid level transmitter is used as the detection instrument. First of all, we must understand the process conditions, process media, whether the object is the original stable tower, or the tank (tank), reactor. The liquid level is measured by the double-flange liquid level transmitter, and the liquid level meter is often displayed at the same time. The process operator uses the local display level gauge as a reference to judge that the measured value of the differential pressure level transmitter is too high. Or low, because the display level gauge is more intuitive. The instrument maintenance personnel should judge and check according to the process conditions and instrument failure phenomena. The idea of determining the fault of the liquid level (level) can be referred to the figure.
Liquid level meter fault analysis diagram (Y means yes; N means no)