Noise has serious harm to people, generally should not exceed 80 decibels. Valve noise can sometimes be more than 100 decibels, making it difficult to get close to it. General control valve noise from the vibration of the valve core, due to high-speed airflow surface produced by the aerodynamic noise, but also due to flash, cavitation, flow caused by the hydrodynamic noise. Among them, fluid flow noise and flash evaporation noise are not very big, and other noises can be considered as follows according to the noise source:
1、Vibration noise prevention and reduction.
Most of this kind of noise is caused by resonance, vibration often accompanied by the noise, but there is a small. The noise can be reduced by increasing the stiffness to increase the damping, reducing the fit of the throttle, guiding clearance, and reducing the transverse vibration. The fundamental way to prevent noise is not to take a passive method to weaken or sound-proof, but to consider the elimination of resonance, change the valve's natural frequency.
2、Cavitation noise prevention.
To prevent vibration noise, resonance elimination should be considered. Similarly, air noise should be considered from the aspects of preventing flash and cavitation or reducing flash and cavitation.
3、Prevention of aerodynamic noise.
When the speed of compressible fluid through the regulating valve is greater than or equal to the speed of sound, it will produce strong noise and vibration, not only produce noise, but also damage the parts, the extent of the noise damage and noise energy, and the noise energy and speed of three square proportional. Therefore, the higher the speed, the louder the noise will be.
Currently, there are generally the following methods to avoid aerodynamic noise:
①Eliminate the noise source, that is, fundamentally limit the throttle valve speed, make it below the speed of sound;
②Choose a low noise control valve, it makes the fluid throttling tortuous flow, mutual interference and collision, to increase resistance, energy consumption, prevent (or reduce) the flow path at any point in the production of supersonic, thereby reducing noise. When the noise is not too much, can be an ordinary sleeve valve;
③Porous current limiter,improve pressure and reduce throttling speed
④Sound insulation material. It can be reduced to about 80 decibels.
⑤Adopt muffler, when the noise is slightly higher, install a muffler behind the valve to absorb the noise and reduce the transmission.