Diaphragm valve sealing principle is to rely on the downward movement of the operating mechanism pressure diaphragm or diaphragm combination and weir lining valve body or straight through lining valve body channel phase close. So that it is sealed. The sealing specific pressure depends on the downward pressure of the closing part to achieve. Because the valve body can line with a variety of soft materials, such as rubber or PTFE, etc.. The diaphragm is also made of soft materials, such as rubber or synthetic rubber lined polytetrafluoroethylene. So it can seal with less sealing force.

Diaphragm valve has only the body, diaphragm and cover assembly of three main components. Diaphragm the lower body chamber and upper cover chamber separated. So that located above the diaphragm stem, stem nut, valve disc, pneumatic control mechanism, electric control mechanism and other parts do not contact with the medium, and will not produce medium leakage, save the packing box sealing structure.

Diaphragm valve structure form and the general valve is very different, is a new type of valve, is a special form of truncated valve.Its opening and closing parts is a piece of soft material made of the diaphragm, the body cavity and the valve cover cavity and drive components separated, is widely used in various fields. Commonly used diaphragm valves are rubber lined diaphragm valve, fluorine lined diaphragm valve, unlined diaphragm valve, plastic diaphragm valve. Diaphragm valve is use as the opening and closing parts of the diaphragm closed flow passage, cut off the fluid. And the body chamber and the cover chamber is separated from the globe valve.

Diaphragm commonly used rubber, plastic and other elastic, corrosion resistant, non-permeable materials. The valve body is made of plastic, glass fiber reinforced plastic, ceramic or metal lining material. Simple structure, good sealing and anticorrosion performance, low fluid resistance. Used for low pressure, low temperature, corrosive and medium containing suspended material. According to the structure, there are roof ridge type, cut-off type, gate type and so on. According to the driving mode is divide into manual, pneumatic, electric.