The main reason for the reduced pressure pneumatic valve noise ( 2)

the fluid mechanical energy is converted to sound energy. Three, aerodynamic noise when steam decompression of the compressible fluid through the reduced pressure within the pneumatic valve parts.
the reduced pressure pneumatic valve causes of noise can be divided into the following three categories:
. Reduced pressure pneumatic valve mechanical vibration noise;
。 Fluid dynamic noise;
。 Aerodynamic noise.
mechanical vibration and can be divided into two forms: one, the mechanical vibration of the noise reduced pressure pneumatic valve components in fluid flow happens when the mechanical vibration.
piping layout is unreasonable and lack of rigidity of pneumatic valve activity parts. (1) low frequency vibration. The vibration is caused by the medium of the jet and pulsation of the reasons is that the pneumatic valve outlet velocity is too fast.
will cause resonance, (2) the high frequency vibration. The natural frequency of vibration on the pneumatic valve and medium flow caused by the excitation frequency is consistent. Reduced pressure pneumatic valve decompression only within a certain range and once a slight change of conditions, the noise is very big. This kind of mechanical vibration noise has nothing to do with the medium flow rate, is due to the reduced pressure pneumatic valve itself more design is not reasonable. Reduce the mechanical vibration noise is reasonably designed vacuum pneumatic valve bushing and pneumatic clearance, the machining precision of the stem, and activity of the natural frequencies of the pneumatic valve parts of rigidity, correctly choosing materials.
2, fluid dynamics of fluid dynamic noise is noise of fluid through the decompression decompression of the pneumatic valve mouth after the turbulence and eddy current generated by the process of production can be divided into two stages:
by the turbulent flow and pressure relief appearance interaction in the pneumatic valve or piping and noise, turbulence noise. The frequency and noise level are low, generally does not constitute the noise problem.
the reduced pressure pneumatic valve in the process of decompression, when the fluid velocity reaches a certain value, the fluid ( Liquid begins to boil, when in bubble of liquid pressure reaches a certain value, the would explode. Air bubbles in the explosion, the localized high pressure and shock wave, the impact of instantaneous pressure of MPa but far away from the explosion center, a pressure decay rapidly. The blast was the cause of the reduced pressure pneumatic valve cavitation and noise is a major factor. Reduce the mechanical vibration noise is reduced pressure pneumatic valve design, must control the decompression decompression of the pneumatic valve value below the critical value, moreover, it is best to Δ p under the initial, (2) the cavitation noise. Because the actual pressure value reduced pressure pneumatic valve Δ p initial value, the liquid begins to cavitation occurs, and the noise will be increased sharply. Also, pay attention to the relative to the fluid flowing direction of pneumatic disc.