In the process of operation, especially in the start-up and shutdown of the air separation unit, one-way force should be avoided on the instrument. During the start-up of the equipment, close the high pressure and low pressure valves firstly, then open the balance valve, and then slowly open the high pressure (or low pressure) valve, so that the measured medium can enter the positive (negative) pressure chamber of the transmitter. If the liquid is to be measured, the gas in the positive (negative) pressure chamber should be discharged from the upper vent. If the gas is measured, drain the liquid accumulated in the positive (negative) pressure chamber from the lower drain screw hole. After discharging the gas (liquid), close the balance valve, and then open the valve on the other side.
When the equipment is shut down, the high pressure (or low pressure) valve should be closed first, then the balance valve should be opened, and then the valve should be closed on the other side. Sometimes when measuring the air flow, there is water in the positive and negative pressure chamber or pipe, so the instrument should be stopped and the water should be drained. Sometimes, the pipeline will be blocked, making the transmitter subject to unidirectional stress, and the output pressure is zero or more than the full scale. At this time, the pressure of 1.0MPa to 5.0Mpa can be injected in the opposite direction and maintained for a few minutes. After eliminating the pressure, if it can return to zero, it means that the diaphragm is not broken. Otherwise, check whether the spring is bent or the diaphragm is broken and whether there is oil leakage. At this point, the diaphragm needs to be replaced.
