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Briefly describe the concept and characteristics of diaphragm valves

First, the diaphragm valve concept:
Diaphragm valves are structurally different from conventional valves in that they rely on a soft rubber or plastic film to control fluid movement. Commonly used diaphragm valves are divided into cast iron diaphragm valves, cast steel diaphragm valves, stainless steel diaphragm valves, and plastic diaphragm valves.
The diaphragm valve is provided with a flexible diaphragm or a combined diaphragm in the valve body and the valve cover, and the closing member is a compression device connected to the diaphragm. The valve seat can be a dome or a wall that is straight through the runner. The advantage of the diaphragm valve is that its operating mechanism is separated from the media path, which not only ensures the purity of the working medium, but also prevents the possibility of the medium in the pipeline from damaging the working parts of the operating mechanism. In addition, there is no need for any form of separate seal at the stem unless it is used as a safety feature in controlling hazardous media. In the diaphragm valve, since the working medium is only in contact with the diaphragm and the valve body, both of which can be used in a variety of different materials, the valve can ideally control a variety of working media, especially for chemically corrosive or suspended particles. medium. The operating temperature of the diaphragm valve is typically limited by the materials used in the diaphragm and body lining, and it operates over a temperature range of approximately -50 to 175 °C. The diaphragm valve has a simple structure and consists of only three main components: the valve body, the diaphragm and the bonnet assembly. The valve is easy to disassemble and repair quickly, and the diaphragm can be replaced in the field and in a short time.
Second, the diaphragm valve features:
<1> The fluid resistance is small.
<2> can be used for media containing hard suspensions; since the medium is only in contact with the valve body and the diaphragm, there is no need for a stuffing box, there is no leakage of the stuffing box, and there is no possibility of corrosion on the stem portion.
<3> Suitable for corrosive, viscous, and slurry media.
<4> cannot be used in places with high pressure.

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