The vacuum diaphragm valve uses the valve stem to press the rubber film directly on the valve seat to cut off or connect the vacuum system. The connection forms are looper flange connection, quick release flange connection and welding connection. Welding connection is divided into welding type I connection (welding at both ends) and welding type II connection (welding at one end and inserting at the other end). The suitable working medium is air and non corrosive gas