Why high pressure check valve has a short life

High-pressure check valve refers to a valve with a work pressure PN of 10 to 80 Mpa. It is a control component in a fluid delivery system and has functions such as cut-off, regulation, diversion, reverse flow, pressure regulation, diversion, or pressure relief. The shortening of its life span mainly has the following three aspects.

First, erosion:

High-pressure check valve in the throttle, medium high-speed flow, with a strong kinetic energy, it can quickly flush the spool, valve seat surface streamlined fine groove, which is the so-called erosion. Especially in the small opening operation, the small clearance gap, the throttling speed reaches the maximum value, the flushing damage also reaches the maximum correspondingly, the huge flushing will make the life of the regulating valve decrease exponentially, this is why the high pressure valve should avoid the small opening degree The reason for the work.

Second, cavitation:

High-speed check valve in the throttling mouth of the high-speed flow of medium, the speed can be increased rapidly, according to the principle of conservation of energy, pressure energy will drop sharply, when the pressure is lower than the saturated vapor pressure (Pv), the liquid will split out of gas The formation of gas-liquid two-phase flow, which is called flash evaporation; when the medium flows through the throttling orifice, the throttling velocity begins to gradually decrease, the pressure begins to gradually recover, and when the pressure recovers to be greater than the saturated vapor pressure, the bubble collapses back. To the liquid state, at the moment of rupture, a strong pressure shock wave is generated, so that the material on the surface of the valve plug and the valve seat impacts into a cellular hole and causes vibration and noise, which is called cavitation. The pressure difference conditions that cause flashing are: P = FL (P1 - PV), where FL is the pressure recovery factor, P1 is the pressure before the valve, and Pv is the saturated vapor pressure at population temperature.

Third, the primary and secondary relationship between cavitation and erosion:

Erosion is the main contradiction when the high-pressure check valve is operated at a small opening degree; cavitation is the main contradiction when working at a large opening. Therefore, the user should try to avoid the small opening when working; the high-pressure check valve manufactured by the manufacturer must have good anti-cavitation measures, otherwise, the control valve will quickly cause cavitation damage.