How to avoid the flash of pneumatic control valve damage?

Pneumatic control valves in the automatic control of modern factory, pneumatic control valve plays a very important role, the production of the factory depends on the correct allocation and control flow of the medium. These controls both the exchange of energy, pressure reducing, or is a simple container loading, will need some final control elements to complete. In the chemical production process flow of pipeline and equipment, there are a lot of fluid flow pneumatic - valve to ensure the normal operation of equipment plays an important role. They have a variety of structural form, suitable for different occasions. Its main function is used to adjust flow, to ensure the stable operation of the equipment. They have the operation is simple, convenient, easy to control etc, so it has been widely applied. But there are too much energy, valve components vulnerability, if use undeserved, design will affect the production. This paper mainly discusses the pipeline flow regulation is too large, transmission fluid temperature is too high, may produce cavitation and flash phenomenon and its damage to the pneumatic control valve and the method to prevent. 1. In the analysis of the causes of corrosion and flash 1. 1 fluid in the fluid flow process in the pneumatic control valve of pneumatic control valve flow channel the flow of process is very complicated, according to the continuity equation: uAp = constant type of u - — Cross section of average flow velocity, m/s; A— — Port area, the m2; p— The density of fluid medium, kg/m3. For incompressible fluids, p = constant, so the uA = constant, that is, fluid velocity and through is inversely proportional to the cross-sectional area of the cross section. At the same time, according to Bernoulli's equation [again 1] : type of z - — Position level, m; p— — Static pressure is strong, Pa; g— — Acceleration of gravity, kg? m/s2。 Ignore the position of the import and export of pipeline fluid level difference, if through the cross section of the flow rate increases, means that the cross section of the pressure drop, when the temperature of the fluid pressure drop to the saturation pressure of Pv, will see vaporization liquid, cavitation or flash occur at the same time. Due to the cavitation phenomenon and flash phenomenon of equipment has great destructive power. We've only study of centrifugal pump cavitation phenomenon is more, the pneumatic control valve in the line may produce the damage caused by cavitation and flash phenomenon did not cause enough attention, so the prevent liquid in the process of flow cavitation and the mechanism of the flash will appear more important.