What is the working principle of the diaphragm valve

Diaphragm valve is a special form of shut-off valve, which appeared in the 1920s. Its opening and closing part is a diaphragm made of soft material, which separates the inner cavity of the lower valve body from the inner cavity of the upper valve cover and the driving parts, so it is called a diaphragm valve. The diaphragm valve is actually just a "clamping" valve. An elastic and disturbing diaphragm is connected to the compression piece with a stud. The compression piece is operated by the valve stem to move up and down. When the compression piece rises, the diaphragm The diaphragm is lifted high, which creates a passage. When the compression member drops, the diaphragm presses on the valve body weir (if it is a weir valve) or presses on the bottom of the contour (if it is a straight-through type). The diaphragm valve is suitable for switching and throttling. For use. The structural design of the diaphragm valve itself is particularly suitable for ultra-pure media or heavily polluted, very viscous liquids, gases, corrosive or inert media. When combined with control equipment, diaphragm valves can better replace other traditional control systems, especially suitable for solid and easily polluted inert media. Products are mainly used in industrial water treatment in biopharmaceutical, food, and power, chemical, electroplating, and other industries. They are also used in the production of semiconductor wafers. Diaphragm valves are especially suitable for transporting corrosive and viscous fluids. , Such as mud, food, medicine, fabric adhesive, etc., because the operating mechanism of the diaphragm valve in the pipeline is not exposed to the conveying fluid, it is not polluting, and does not require packing, nor is the valve stem packing part It may leak.

The characteristics of the diaphragm valve are as follows:
1. The most prominent feature of the 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 clack and other parts located above the diaphragm are not corroded by the medium, and the packing seal structure is omitted. Produce medium leakage.
2. Diaphragm made of soft seal such as rubber or plastic has better sealing performance. Since the diaphragm is a vulnerable part, it should be replaced regularly according to the characteristics of the medium.
3. Limited by the diaphragm material, the diaphragm valve is suitable for low pressure and relatively low temperature occasions.
4. Diaphragm valves can be divided into six types according to the structure: house type, DC type, cut-off type, straight-through type, gate type and right-angle type; the connection form is usually flange connection; according to the driving mode, it can be divided into manual, electric and pneumatic There are three types, of which pneumatic drives are divided into three types: normally open, normally closed and reciprocating.