In use to avoid making the instrument one-way force, especially when driving and parking to pay attention to. When driving, you should first close the high and low pressure valves, then open the equalization valve, and then slowly open the high (or low) pressure valve, so that the measured medium enters the positive (negative) pressure chamber of the transmitter. If the liquid is measured, the gas in the positive (negative) pressure chamber should be discharged from the upper exhaust screw hole; if the gas is measured, the accumulated liquid in the positive (negative) pressure chamber should be discharged from the liquid discharge screw hole below. After draining the gas (liquid), close the equalizing valve and then open the valve on the other side. When stopping the unit, care should be taken to close the high (or low) pressure valve first, then open the equalizing valve, and then close the valve on the other side. Sometimes when measuring air flow, there is water in the positive and negative pressure chambers or pipes, the meter should be stopped and the stored water released. Sometimes there is a pipe blockage, so that the transmitter one-way force, the output pressure is zero or more than the full scale, then you can reverse the direction of play into the 1.0 ~ 5.0MPa pressure and keep a few minutes. When the pressure is eliminated, if it can return to zero, the diaphragm box is not bad. Otherwise, check if the spring is bent or the cartridge is ruptured and leaking oil. In this case, the diaphragm box should be replaced.