Discussion and requests for help regarding gauge flushing

This aspect can be considered in two parts: for instruments in the SIS system, continuous flushing with a low flow rate can be used, while for ordinary instruments in the DCS, intermittent flushing is an appropriate method. Generally, level gauges use metal floats or double-flange differential pressure level gauges. In the case of flange-type differential pressure level gauges, continuous flushing with washing water can damage the lifespan of the diaphragm in the diaphragm box. Since the instruments in the SIS system are part of the ESD shutdown system, any distortion during operation of the system can easily lead to incorrect interlock responses; however, in many cases it is a 3-to-2 signal issue, so it should not be a serious problem. If the instruments in the SIS system are to be flushed intermittently, the bypass should be interconnected during flushing; after the flushing is complete, it is necessary to verify that the on-site feedback signals are within the normal range before reactivating the interlock. In the early stages of system startup, some plants made mistakes in this regard; no bypass was used during the processing process, which led to the system shutting down.

For level gauges equipped with interlocks, it is necessary to first activate the interlock before flushing, in order to prevent accidents; high-pressure deionized water can be used for flushing. . . . . . . .

Thank you for your answer; it’s very helpful