Why Is A Diaphragm Valve A Special Type Of Shut-off Valve
Mar 13, 2024| Why is a diaphragm valve a special type of shut-off valve
The construction method of diaphragm valve is very different from that of ordinary valves. It is a new type of valve and a special type of shut-off valve. Its opening and closing parts are a diaphragm made of soft material, which separates the valve body cavity from the valve cover cavity and driving components. It is now widely used in various fields. The commonly used diaphragm valves include rubber lined diaphragm valves, fluorine lined diaphragm valves, non fabric diaphragm valves, and plastic diaphragm valves. Diaphragm valves use corrosion-resistant materials for the valve body and corrosion-resistant diaphragms to replace the valve core components, utilizing the movement of the diaphragm for conditioning purposes. The valve body material of the diaphragm valve is made of cast iron, cast steel, or forged stainless steel, and lined with various corrosion-resistant or wear-resistant materials, diaphragm material rubber, and polytetrafluoroethylene. The diaphragm of the fabric has strong corrosion resistance and is suitable for regulating highly corrosive media such as strong acids and alkalis.
The diaphragm valve has a simple structure, low fluid resistance, and greater flow capacity compared to other types of valves of the same standard; No leakage, can be used for conditioning high viscosity and suspended particle media. The barrier separates the medium from the upper chamber of the valve stem, so there will be no leakage of the medium without packing. However, due to barriers and limitations in fabric information, the pressure resistance and temperature resistance are poor, usually only applicable to pressures of 1.6 MPa and below 150 ℃.
The flow characteristics of diaphragm valves are close to the fast opening characteristics, and are approximately linear before 60% of the stroke, with little change in flow after 60%. Pneumatic diaphragm valves can also be equipped with reaction signals, limiters, and locators to meet the needs of self-control
programming, or flow regulation. The reaction signal of the pneumatic diaphragm valve adopts non-contact sensing technology. This product uses a thin film propulsion cylinder instead of a piston cylinder, eliminating the disadvantage of piston rings being easily damaged and forming leaks that prevent the valve from being pushed open and closed. When the air source malfunctions, the handwheel can still be operated to open and close the valve.
Characteristics of diaphragm valves:
(1) Low fluid resistance.
(2) Can be used for media containing hard suspended solids; Because the medium only touches the valve body and diaphragm, there is no need for a packing box, and there is no problem of leakage in the packing box, which may not cause corrosion to the valve stem.
(3) Suitable for corrosive, viscous, and slurry media.
(4) Cannot be used in high pressure situations.
Installation and protection of diaphragm valves:
① Before installing the diaphragm valve, carefully check whether the operating conditions of the pipeline are consistent with the scope of use of this valve rule, and clean the inner chamber to avoid dirt jamming or damage to the sealing components.
② Do not apply oil or grease on the surface of the rubber fabric layer and rubber barrier to prevent rubber swelling and affecting the service life of the diaphragm valve.
③ Handwheels or transmission structures are not allowed for lifting purposes and are prohibited from being bumped.
④ When manually operating the diaphragm valve, do not use auxiliary levers to prevent excessive torque from damaging the driving components or sealing parts.
⑤ Diaphragm valves should be stored in dry and ventilated rooms, and stacking is prohibited. The two channels of inventory diaphragm valves must be sealed, and the opening and closing parts should be in a slightly open state.