High pressure pneumatic valve analysis of the causes of short service life

high pressure pneumatic valve is called pressure PN ~ Mpa at work pneumatic valve, is a fluid conveying system in the control unit, a cut-off, regulation, guide, to prevent the reverse flow, voltage regulator, the leakage of the shunt or overflow, and other functions. The life cut short is mainly has the following three aspects.
　　
　　( Erosion

in the throttle opening, medium to high speed flow, with a strong momentum, it can quickly will pneumatic valve, pneumatic valve seat surface, through streamlined grooves, this is called erosion. Work especially in the small open degree, throttling, small gap throttling reach maximum speed, reach maximum scour damage correspondingly, huge scouring will bring down the regulating pneumatic valve life exponentially, this is why high pressure pneumatic valve to avoid the cause of the small open degree work.
　　
　　( Cavitation

the high-speed flow of throttling mouth medium, its speed can increase sharply, according to the principle of conservation of energy, pressure will drop sharply, when pressure is lower than the saturated vapor pressure ( After Pv, liquid will split out gas, formation of gas-liquid two phase flow, this is the so-called flash; When the medium flows through the throttle opening, throttling rate began to drop, the pressure gradually began to recover, when pressure recovery is greater than the saturation vapor pressure, back to liquid bubble burst, just at the instant of the rupture, strong pressure shock wave, make the function of the pneumatic valve, pneumatic valve seat material impact on the surface of the honeycomb holes, and cause vibration and noise, this is called cavitation. The differential pressure caused by flash condition is: delta P = FL ( P - PV, FL as the pressure recovery coefficient, P for pneumatic valve before pressure, PV saturated vapor pressure of population temperatures.
　　
　　( Cavitation and erosion progression

small open degree, erosion is the main contradiction; The big opening, cavitation is the main contradiction. So, when users try to avoid a small open degree of work; Manufacturer of manufacturing high pressure pneumatic valve must have good anti cavitation measures, otherwise, regulating pneumatic valve cavitation damage soon.