Working principle of welding pneumatic diaphragm valve:
Welded pneumatic diaphragm valves replace the spool assembly with a corrosion-resistant lined body and a corrosion-resistant diaphragm, using the diaphragm movement to regulate. Diaphragm valve body material made of cast iron, cast steel, or cast stainless steel, and lined with a variety of corrosion resistant or wear-resistant materials, diaphragm material rubber and PTFE. The diaphragm of the lining has strong corrosion resistance, which is suitable for the regulation of strong corrosive media such as strong acid and alkali.
Diaphragm valve has simple structure, small fluid resistance, flow capacity is larger than other types of valves with the same specifications; No leakage, can be used for the adjustment of high viscosity and suspended particles medium. The diaphragm isolates the medium from the stem upper chamber, so there is no packing medium will not leak. However, due to the limitations of diaphragm and lining materials, the pressure resistance and temperature resistance is poor, generally only suitable for 1.6MPa nominal pressure and 150℃ below.
The flow characteristic of diaphragm valve is close to the fast opening characteristic, which is approximately linear before 60% stroke, and the flow rate is little changed after 60%. Pneumatic diaphragm valves can also be equipped with feedback signals, limiter and positioner devices, in order to meet the needs of automatic control, program control or flow regulation. Pneumatic diaphragm valve feedback signal using contactless sensing technology. The product uses thin film propulsion cylinder, instead of piston cylinder, eliminate the piston ring is easy to damage, resulting in leakage and can not push the valve opening and closing disadvantages. When the air source is faulty, it can operate the hand wheel to open and close the valve.
Welding pneumatic diaphragm valve sealing principle:
The sealing principle of the diaphragm valve depends on the downward movement of the operating mechanism to press the diaphragm or diaphragm assembly and the weir lining valve body or straight lining valve body channel close, so as to achieve the seal. The sealing pressure depends on the downward pressure of the closing parts to achieve. Because the valve body can be lined with a variety of soft materials, such as rubber or PTFE; The diaphragm is also made of soft materials, such as rubber or synthetic rubber lined teflon, so with a small sealing force can achieve a complete seal.
Welding pneumatic diaphragm valve for what occasions:
Welded pneumatic diaphragm valve is a special form of truncation valve, the opening and closing part is a diaphragm made of soft material, it will be the valve body cavity and the valve cover cavity separated. Due to the limitations of valve body lining process and diaphragm manufacturing process, larger valve body lining and larger diaphragm manufacturing process are difficult, so the diaphragm valve should not be used for larger diameter, generally used in ≤DN200 pipeline.
Diaphragm valve due to the diaphragm material limitation, diaphragm valve is suitable for low pressure and low temperature occasions. Generally do not exceed 180℃. Because diaphragm valve has good anti-corrosion performance, it is generally used in corrosive media devices and pipelines. Due to the use of diaphragm valve temperature applicable medium is limited by diaphragm body lining material and diaphragm material.