Negative pressure safety valve FA72H-10c is a supporting part on the Roots fan, which is generally applicable to the AR-S series of Roots blowers. Its main function is to prevent the blower from failing by opening the safety valve when the blower's compliance exceeds the set pressure of the safety valve. Negative pressure safety valve FA72H-10c shall be installed on the horizontal pipeline and vertically through the tee during installation, i.e. its axis shall be ensured to be perpendicular to the ground. Negative pressure safety valve FA72H-10c in the process of use, such as found that the safety valve sensitivity is reduced, should immediately carry out the valve seat and spool cleaning. The method is to unscrew the bonnet, remove the spring and clean it with clean kerosene or gasoline. In order to ensure the service life and sensitivity of the safety valve, the user should regularly clean the parts of the safety valve according to the usage condition.