Sanitary Diaphragm Valve is a special form of shut-off valve that appeared in the 1920s. Its opening and closing parts are a diaphragm made of soft material, which separates the inner cavity of the valve body from the inner cavity of the valve cover and the driving components, so it is called a pneumatic diaphragm valve. The outstanding feature of the pneumatic diaphragm valve is that the diaphragm separates the inner cavity of the lower valve body from the inner cavity of the upper valve cover, so that the valve stem, valve disc and other parts above the diaphragm are not corroded by the medium, the packing sealing structure is omitted, and no medium leakage occurs.
1. The diaphragm made of soft seals such as rubber or plastic has good sealing performance. Since the diaphragm is a wearing part, it should be replaced regularly according to the characteristics of the medium.
2. Due to the limitation of the diaphragm material, the diaphragm valve is suitable for low pressure and relatively low temperature occasions.
3. Diaphragm valves can be divided into six types according to their structure: house type, direct current type, stop type, straight-through type, gate type and right-angle type; the connection form is usually flange connection; according to the driving mode, they can be divided into three types: manual, electric and pneumatic, among which pneumatic drive is divided into three types: normally open, normally closed and reciprocating.

4. It is generally not suitable for use in pipelines with temperatures above 60 degrees and for conveying organic solvents and strong oxidizing media, nor is it suitable to use pneumatic diaphragm valves in pipelines with higher pressures.

Pneumatic diaphragm valves are clamping valves, which are mainly used for opening and closing on pipelines.

Pneumatic diaphragm valves have two main advantages: one is that the valve does not require a separate valve stem packing sealing structure, and the diaphragm plays a sealing role on the valve stem while cutting off the medium; the other is that the diaphragm with strong flexibility is reliable in closing, and can even cut off dirty liquids well. Therefore, the operating mechanism and the medium channel are separated, making the pneumatic diaphragm valve not only suitable for the food industry and the medical and health industry, but also for some difficult-to-transport media and dangerous media.
Generally, diaphragm valves are recommended for use in conditions requiring strict sealing performance, mud media, wear, light structure, low pressure cutoff (small pressure difference), small leakage to the atmosphere, and abrasive media. Diaphragm valves can be used in situations of two-position adjustment, throttling, channel shrinkage, low noise, cavitation and vaporization, and small operating torque. Diaphragm valves are not selected under the conditions of high temperature media, high pressure media, high pressure cutoff (large pressure difference), fast opening and closing action, and short structure length, except for metal diaphragm valves.