Frequent failures of field instruments

Field instrument measurement parameters are generally divided into four parameters: temperature, pressure, flow, and liquid level. Now according to the different measurement parameters, to analyze the failure of different field instruments. 1. First of all, before analyzing field instrument failures, it is necessary to have a thorough understanding of the production process, production process and conditions of the relevant instrument system, and understand the design plan and design intent of the instrument system. The measurement parameters of the instrument field instrument are generally divided into temperature, pressure, and flow. , Four parameters of liquid level.　　　　 Now according to the different measurement parameters, to analyze the failure of different field instruments. 1. First of all, before analyzing on-site instrument failures, it is necessary to thoroughly understand the production process, production process and conditions of the relevant instrument system, understand the design plan, design intent of the instrument system, and the structure, characteristics, performance and parameter requirements of the instrument system. 2. Before analyzing and checking the failure of the on-site instrument system, it is necessary to understand the production load and the parameter changes of the raw materials from the on-site operators, check the record curve of the faulty instrument, and conduct a comprehensive analysis to determine the cause of the instrument failure.　　　　3. If the record curve of the instrument is a dead line (the line with no change is called dead line), or the record curve was originally fluctuating, it suddenly becomes a straight line; the fault is probably in the instrument system. Because most of the current recording instruments are DCS computer systems, the sensitivity is very high, and the changes of parameters can be very sensitively reflected. At this time, you can artificially change the process parameters to see the curve changes. If there is no change, it is basically concluded that there is a problem with the instrument system; if there is a normal change, it is basically concluded that there is no major problem with the instrument system.　　　　4. When the process parameters are changed, it is found that the recording curve has a sudden change or jumps to the maximum or minimum. At this time, the fault is often in the instrument system.　　　　 5. Before the failure occurred, the record curve of the instrument has been behaving normally. After the fluctuation, the record curve becomes irregular or makes the system difficult to control, even manual operation cannot be controlled. At this time, the failure may be caused by the process operating system.　　　　 6. When the DCS display instrument is found to be abnormal, you can go to the site to check the indication value of the same intuitive instrument. If they are very different, it is likely that the instrument system is malfunctioning.　　　　 In short, when analyzing the causes of field instrument failures, pay special attention to changes in the characteristics of the measured control object and control valve, which may be the cause of the field instrument system failure. Therefore, we must comprehensively consider and analyze carefully from the two aspects of the field instrument system and the process operating system to check the reasons.