Import compressed air pressure pneumatic valve of several major reasons for the noise

import compressed air 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.
a, mechanical vibration noise reduced pressure pneumatic valve components in fluid flow will produce mechanical vibration, mechanical vibration and can be divided into two forms:
(1) low frequency vibration. The vibration is caused by a medium of jet and the pulse, the reason is that the pneumatic valve outlet velocity is too fast, piping layout is unreasonable and pneumatic valve parts of insufficient rigidity, etc.
(2) the high frequency vibration. The natural frequency of vibration on the pneumatic valve and medium flow caused by the excitation frequency is consistent, will cause resonance, it is compressed air pressure pneumatic valve decompression only within a certain range, and if 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, reasonable design of vacuum pneumatic valve bushing and pneumatic valve stem, machining accuracy, pneumatic valve clearance and activity of the natural frequencies of the rigidity of the parts, correctly selecting material, etc.
2, fluid dynamics of fluid dynamic noise is noise of fluid through the decompression decompression of the pneumatic valve mouth after the turbulence and vortex, produced by the produce process can be divided into two stages:
1) turbulence noise, namely by the turbulent fluid and surface interaction in the reduced pressure pneumatic valve or piping and noise, compress air vacuum pneumatic valve the frequency and noise level are low, generally does not constitute the noise problem.
(2) the cavitation noise, the reduced pressure pneumatic valve in the process of decompression, when the fluid velocity reaches a certain value, the fluid begins to boil, when in bubble of liquid pressure reaches a certain value, would explode. Air bubbles in the explosion, the local 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.
measures for decreasing the mechanical vibration noise is reduced pressure in the design of pneumatic valve, must control the decompression decompression of the pneumatic valve value below the critical value, moreover, had better be under Δ initial p, because the actual pressure value reduced pressure pneumatic valve reaches Δ p initial value, liquid began to produce cavitation, and noise will increase sharply. In addition, the compressed air pressure pneumatic valve also notice relative to the fluid flowing direction of pneumatic disc.
3, aerodynamic noise when steam compressible fluid through reduced pressure reduced pressure parts, pneumatic valve fluid noise of mechanical energy is converted to sound energy is called the aerodynamic noise. This noise is a majority in vacuum pneumatic valve noise and deal with the trouble of noise. The causes of this kind of noise can be divided into two cases, one is generated due to fluid turbulent flow, the second is caused by fluid reaches a critical velocity of shock wave. Aerodynamic noise is not completely eliminated, when because of the reduced pressure pneumatic valve in the reduced pressure caused by fluid turbulence is inevitable. To sum up, basically, reduced pressure pneumatic valve noise is related to its own design and manufacturing process.