This is a pressure gauge which has been designed to measure minute differential pressure of 2 kPa(200 mmH2O) or smaller. For the contact, a microswitch rich in application and with high reliability has been applied. Using This Differential Pressure Switch If the pressure larger than differential pressure is applied to the one pressure connecting port, the mechanism of the differential pressure switch will be damaged. So, careful attention is required. Especially at the time of starting and finishing, this type of phenomena can occur. Therefore, a bypass cock or a bypass valve is recommended.