Diaphragm valves are usually globe valves that use elastic diaphragms as opening and closing parts to close the flow channel, cut off the fluid, and separate the inner cavity of the valve body from the inner cavity of the bonnet. Diaphragms are often made of elastic, corrosion-resistant, and non-permeable materials such as rubber and plastic. The valve body is mostly made of plastic, metal or metal lining. The structure is simple, the sealing and anti-corrosion performance are good, and the fluid resistance is small. It can be used for low-pressure, low-temperature, corrosive and suspended matter media. According to the structural form, it is divided into ridge type (weir type), straight-through type, etc. According to the driving mode, it is divided into manual and pneumatic. It is usually mainly used for cut-off, but it can also be adjusted by installing a positioner.