The function of the three-valve group is to conduct or cut off the positive and negative pressure chambers of the differential pressure transmitter and the pressure guiding pipe, or to cut off or conduct the positive and negative pressure chambers. The five-valve group integrates high and low pressure drain valves on the basis of the three-valve group, and there is no difference in use with the three-valve group. Although the high and low pressure blowdown valve is added to the five-valve group, it is generally not used for blowdown. It is usually used to discharge the gas and liquid in the membrane box of the transmitter. After using it to empty the zero point, the blowdown still needs to be done after the transmitter. Because the five-valve group is installed before the transmitter, it can only discharge the pressure guiding pipe, and when the diaphragm box has dirt, it cannot be discharged from the five-valve group. But after using the five-valve group, it is convenient to check and calibrate the transmitter online.
