Structure of Diaphragm Valve
Diaphragm valves are different from general valve of conventional structure and working principle. It is the self structure, does not require an external energy supplying, it works through the process of fluid (compressed air)to job. Compressed air throttle holes into the diaphragm valve chamber.
Under static conditions, compressed air inlet pressure and diaphragm valves indoor air pressure is equal. Diaphragm valve is closed under the action of spring force. Once empty charged, the air of air chamber vents through the vent port, then pressure drops, the diaphragm valve is opened automatically, compressed air enters the filter for cleaning. After power loosing of solenoid valve, air chamber has to re-establish balancing, them diaphragm valve closed.
Features of Diaphragm Valves – it is one of the earliest control valve, it has the following features:
(1) Soft rubber diaphragm valves can cut off the media with no leakage.
(2) Rubber diaphragm valves have better corrosion-resistant, it also be used as a corrosion-resistant material, and even continued to this day.
(3) Design is simple and with “self-cleaning” function, can be used for muddy media.
(4) It can open features. But as a corrosion resistant regulation valve, it is unavailable. We have to use the front half function of quick opening feature, so its effective stroke is short, it is poor to regulation.
(5) Like a fatigue test specimen, forced it to fold up and down, easily damaged. Because the diaphragm is an unreliable parts, it make the valve a short service life, this is a fatal weakness.
(6) When closing, the media forcing the diaphragm upwards Crest, and unbalanced force is large, the valve requires a larger thrust actuator. Therefore, must use extremely large and heavy actuator to guarantee the function. The valve becomes very heavy, maybe the twice times of ball valves ?
(7) Especially need to be emphasized that corrosion resistant material is more and more, especially in the late 80s, the lining technology of fluorine plastic was solved, and fluororubber lined ball valve developed. Because the fluorine plastic rubber is with better corrosion resistance and heat resistance, and the strength of ball valve’s ball is much better than the diaphragm of diaphragm valve for ten times as much as one hundred times, so we suggest that do not choose diaphragm valve for the shut-off and regulation of corrosive medium. It is better to use corrosion resistant lined ball valve, butterfly valve , and full PTFE single-seat valves.
*The article was collected and revised by WELLGREEN PROCESS SOLUTIONS – Your reliable solution of sanitary valve and fittings .