Solution to high noise of globe control valve

Solution to high noise of globe control valve

1 Method of eliminating resonance noise of globe control valve

Only when the globe control valve resonates, there is energy superposition to produce more than 100 dB of strong noise. Some show strong vibration and little noise, while others have weak vibration and very large noise; Some have large vibration and noise. This noise produces a monotonous sound, and its frequency is generally 3000 ~ 7000hz. Obviously, if the resonance is eliminated, the noise will naturally disappear.

2 Method of eliminating cavitation noise of globe control valve

Cavitation is the main source of hydrodynamic noise. During cavitation, bubble rupture produces high-speed impact, resulting in strong local turbulence and cavitation noise. This noise has a wide frequency range and produces rattle sound, which is similar to the sound emitted by sand and stone in liquid. Eliminating and reducing cavitation is an effective way to eliminate and reduce noise.

3 Use thick wall pipeline method of globe control valve

The use of thick wall pipe is one of the sound path treatment methods. The use of thin wall can increase the noise by 5dB, and the use of thick wall tube can reduce the noise by 0 ~ 20dB. The thicker the wall of the same pipe diameter, the larger the pipe diameter of the same wall thickness, the better the noise reduction effect. For example, when the wall thickness of DN200 pipe is 6.25, 6.75, 8, 10, 12.5, 15, 18, 20 and 21.5mm respectively, the noise can be reduced by - 3.5, - 2 (i.e. increase), 0, 3, 6, 8, 11, 13 and 14.5db respectively. Of course, the thicker the wall, the higher the cost.

4 Sound absorbing material method of globe control valve

This is also a common and most effective sound path processing method. The noise source and the pipeline behind the valve can be wrapped with sound-absorbing materials. It must be pointed out that since the noise will propagate over a long distance through fluid flow, the effectiveness of noise elimination will end where the sound-absorbing material package and the thick wall tube are used. This method is applicable to the situation where the noise is not very high and the pipeline is not very long, because it is a more expensive method.

5 Series silencer method of globe control valve

This method is applicable to the silencing of aerodynamic noise. It can effectively eliminate the noise inside the fluid and suppress the noise level transmitted to the solid boundary layer. This method is the most effective and economical for places where the pressure drop ratio before and after the mass flow high-pressure valve is high. The use of suction series silencer can greatly reduce the noise. However, economically, it is generally limited to attenuation to about 25dB.

6 Speaker isolation method of globe control valve

Use speakers, houses and buildings to isolate the noise source inside, so as to reduce the noise of the external environment to an acceptable range.

7 Series throttling method of globe control valve

When the pressure ratio of theglobe control valve is high (△ P / P1 ≥ 0.8), the series throttling method is adopted, that is, the total pressure drop is dispersed in theglobe control valve and the fixed throttling element behind the valve. For example, diffusers and multi hole flow restrictors are the most effective methods to reduce noise. In order to obtain the best diffuser efficiency, the diffuser (solid shape and size) must be designed according to the installation of the first part, so that the noise level generated by the valve is the same as that generated by the diffuser.

8. Low noise valve shall be selected of globe control valve

The low noise valve decelerates gradually according to the tortuous flow (multi-channel and multi groove) of the fluid through the valve core and valve seat, so as to avoid supersonic at any point in the flow path. There are various forms and structures of low-noise valves (some designed for special systems) for use. When the noise is not very large, the low-noise sleeve valve can reduce the noise by 10 ~ 20dB, which is the most economical low-noise valve.