College】 【weak cold pressure controller failure analysis】..

<br> pressure controller instrumentation system fault analysis steps: <BR> <BR> First, the basic field instrument system failure analysis steps are generally divided into field instruments measured parameters of temperature, pressure, flow, level four parameters. .In accordance with the measurement of different parameters, to analyze the different on-site instrument failure lies. .1. .First, the analysis of field instrument malfunction ago, to more thorough understanding of the relevant instrument system production process, production technology and conditions of the situation, understand the instrument system design, design intent, instrument system structure, features, performance and parameter requirements. .2. .Check the field instrument in the analysis of system failure before the operation to the on-site workers and materials to find out about the parameters of the load changes, view the record of instrument failure curve, a comprehensive analysis to determine the reason for instrument failure. .3. .If the meter records curve is a dead line (the line that says there is no change in dead line), or record volatility curve for the original, and now suddenly become a straight line; fault is likely in the instrument system. .Because most of the current recording instruments DCS computer systems, sensitivity is very high, parameter changes can be very sensitive response to it. .At this point a change can be artificially process parameters and see the change curve. .If we do not change, the basic instrument is the system to determine a problem; if the normal variation, the basic instrumentation systems to determine no major problems. .4. .Changes in process parameters, we found that mutations in, or jump to record curve maximum or minimum, then the failure is also often the instrument system. .5. .Failure has occurred before the instrument records the performance of the normal curve, volatility curve becomes erratic after the record or make the system difficult to control, and even manual operation can not control, then failure may be caused by the operating system process. .6. .When the meter showed that DCS is not normal, you can to inspect the instrument is indicating the same intuitive, if they are very different, it is likely that instrumentation system failure. .In short, the analysis of field instrument malfunction, we should pay special attention to the tested and control valves control the characteristics of the object changes, which may be caused by field instrumentation system failure. .So, we live instrumentation systems and processes from the operating system into account two aspects, careful analysis, check why. .<BR> <BR> Second, the four measured parameters instrument control system fault analysis Step 1. .Instrument System pressure controller pressure controller failure analysis step analysis instrument system failure, the first thing to note two points: the system to use more electric instrument measuring instrument, direction, control; the system is often lag the larger the measurement instrument. .(1) pressure controller, an indicator of instrumentation systems to the maximum or minimum sudden change, usually instrumentation system failure. .Instrumentation systems for measuring pressure controller lag large sudden change does not occur. .Failure at this time mostly Thermocouple, RTD, compensation wire break or malfunction caused by the transmitter amplifier. .(2) pressure control instrumentation systems indicates rapid oscillations occur, mostly caused by improper adjustment of PID control parameters. .(3) pressure control instrumentation systems indicates a slow sharp fluctuations, probably caused by the change due to process operations, such as when there is no change in process operation, it is likely that the failure instrument control system itself. .(4) pressure controller of the system itself fault analysis steps: check whether the change of control valve input signal, the input signal does not change, valve action, the first diaphragm valve leak membrane; check valve positioner input signal changes, the input .signal does not change, the output signal change, a fault locator; check the locator input signals have changed, and then check whether the change in controller output, if the regulator does not change the input, output changes, now is the regulator's own fault. .2. .Pressure controller instrumentation system failure analysis step (1) pressure control system instrument indicator appears on the rapid oscillatory move, first check whether the process operation changes, which are mostly technical operation and the regulator is not good cause PID parameter tuning. .(2) pressure control system instrumented found dead in line, process or operational changes the pressure does not change direction, the general failure in the pressure measurement system, first check the pressure measuring catheter system is introduced there is the phenomenon of blocking, no blocking, check the pressure .transmitter output system without change, there is a change, fault the measurement instructions in the controller system. .3. .Flow control instrument system failure analysis step (1) flow control instrumentation systems to achieve the best indication hours, first check the on-site instrumentation, and if normal, then the fault in the display instrument. .When the on-site instrumentation instructions are minimal, check valve opening, if the valve opening is zero, often between the regulator valve to malfunction. .When the on-site instrumentation indicates minimal normal valve opening, the failure is probably because the system pressure is not enough, the system pipe plug, the pump is not on the amount of medium crystal, and other causes improper operation. .If the instrument's failure reasons: orifice differential pressure flow meter tube may be blocked positive lead; differential pressure transmitter leakage pressure chamber; mechanical gear flowmeter is stuck or blocked filters and so on. .(2) flow control instrumentation systems indicates value is reached, the instrumentation most often will direct. .At this point you can manually adjust the valve to open a large remote control or off small, if the traffic can come down for the process operation is generally caused. .If the flow values do not fall down, it is the instrument causes the system to check the flow control valve instrument system is action; check the meter measuring system is properly cited pressure; check the meter signal transmission system is normal. .(3) flow control instrumentation systems indicate more frequent fluctuations in the value can be changed to manual control, if volatility decreases, it is the instrument or instruments reasons PID control parameters is inappropriate, if the fluctuations are still frequent, is the operational aspects of technology .causes. .4. .Level control instrumentation system fault analysis procedure <BR> <BR> (1) level control instrumentation systems to the maximum indicated value changes or the most hours, you can check to see if the normal instrumentation, such as indicating normal, to the level control .manual remote control level, see level changes. .Such as the level can be stabilized at a certain range, then the fault in the liquid level control system; such as stability could not level, is generally caused by the failure process system, from the technological aspects of the cause. .(2) indicates differential pressure liquid level control instruments and on-site direct reading instruction is not on the indicating instrument, first check the site meter direct reading instruction is normal, if the instructions properly, check the negative pressure differential pressure liquid level instrument guide .pressure tube sealing liquid leaks; if leakage, re-potting medium, adjusting zero; no leakage, it may be a negative migration instrument wrong, re-adjust the amount of the instrument indicating normal migration. .(3) level control instrumentation systems fluctuations in the frequent change of indication, the first to analyze the capacity of the size of the object level control, to analyze the causes, large capacity and is generally caused by instrument failure. .Small capacity of the first analysis of whether there are changes in process operating conditions, if any change is likely to be caused by fluctuations in the frequent process. .If no change may be caused by instrument failure. .These are just four parameters individually controlled site-site failure analysis instrument, the actual site there are some complex control circuits, such as cascade control, sub-process control, process control, interlock control and so on. .Analysis of these failures is even more complex, should be approached..