Diaphragm valve is one of the earliest control valve, it has the following features: (1) soft rubber diaphragm valve can cut off the media leak-proof. (2) Rubber has a certain degree of corrosion resistance. Before the 1960's, there was no better corrosion-resistant material, and it was often used as a corrosion-resistant material to promote and even extend to today. (3) simple flow path, a "self-cleaning" effect, can be used for dirty media. (4) open character, but when used as a corrosion-resistant control valve, had to use the first part of the quick opening characteristics, the effective short stroke, poor regulation quality. (5) As a fatigue test piece, forcing it to collapse up and down, easily damaged, because the diaphragm is an unreliable part, resulting in shorter valve life, which is a fatal flaw. Because of this, the author emphasizes in recent years: Should eliminate the diaphragm valve, with the ball valve, full-featured ultra-light valve replaced. (6) When closed, the media force to the diaphragm up, unbalanced force larger, requiring a larger actuator thrust, you must choose particularly large and stupid heavy actuator, the valve weight becomes Very bulky, twice the size of a ball valve, 3-4 times the size of a full-featured ultralight valve. (7) In particular, the need to emphasize that: more and more corrosion-resistant materials, especially in the late l80 fluorine plastic process to be solved, the fluorine-lined ball valve available. As fluorine plastic than rubber corrosion-resistant, temperature, and the ball valve core is far more than the diaphragm valve diaphragm ten times stronger, it is recommended in the corrosive medium cut off and adjust the situation, try not to use diaphragm valve, the choice of corrosion-resistant lining Fluorine ball valve, butterfly valve and all PTFE single-seat valve. May wish to cite an example: In the water treatment system, the valve used in desalination water plant, 10 years ago, both abroad and domestic installations, are selected fluorine plastic diaphragm valve, and its long service life is about a year, Short 3 to 6 months, therefore, constantly changing the diaphragm. After the selection of our recommended special water treatment valve, the problem is well resolved, life expectancy up to 7 to 8 years, generally can be used for 3 to 5 years.
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