Many staff members are very distressed. How can we eliminate this noise? Long Zhu has compiled several methods for you, and you can refer to them.
One, using sound-absorbing material method
This is also a common and most effective way to deal with the sound path. Sound-absorbing materials can be used to cover the noise source and the pipeline behind the valve. It must be pointed out that because noise will travel long distances through fluid flow, where the sound-absorbing material is packaged and where thick-walled pipes are used, the effectiveness of noise elimination will end. This method is suitable for situations where the noise is not very high and the pipeline is not very long, because it is a more expensive method.
Two, series throttling method
When the pressure ratio of the regulating valve is high (P/P1≥0.8), the series throttling method is adopted, which is to disperse the total pressure drop on the regulating valve and the fixed throttling element behind the valve. Such as the use of diffusers, porous restrictor, this is the most effective way to reduce noise. In order to get the best diffuser efficiency, the diffuser (physical shape and size) must be designed according to the installation situation of each piece, so that the noise level produced by the valve is the same as the noise level produced by the diffuser.
Three, the method of eliminating resonance noise
Only when the regulating valve resonates, the energy is superimposed to produce a strong noise of more than 100 decibels. Some are characterized by strong vibration and low noise, and some vibration is weak, but the noise is very large; some vibration and noise are large. This kind of noise produces a single-tone sound, the frequency of which is generally 3000 to 7000 Hz. Obviously, when resonance is eliminated, the noise naturally disappears.
Four, series muffler method
This method is suitable for aerodynamic noise reduction. It can effectively eliminate the noise inside the fluid and suppress the noise level transmitted to the solid boundary layer. This method is most effective and economical for places where the mass flow is high or the pressure drop ratio before and after the valve is high. The use of absorbing tandem silencers can greatly reduce noise. However, from economic considerations, it is generally limited to attenuation to about 25 decibels.
Five, elimination of cavitation noise
Cavitation is the main source of hydrodynamic noise. During cavitation, the bubble breaks and produces high-speed impact, which causes strong turbulence locally and produces cavitation noise. This kind of noise has a wide frequency range and produces a grating sound similar to the sound produced by fluid containing sand and gravel. Eliminating and reducing cavitation is an effective way to eliminate and reduce noise.
Six, choose low noise valve
The low noise valve decelerates gradually according to the tortuous flow path (multi-channel, multi-channel) of the fluid passing through the regulating valve core and regulating valve seat to avoid supersonic velocity at any point in the flow path. There are many forms and structures of low-noise valves (designed for special systems) for use. When the noise is not too big, choose a low-noise sleeve valve, which can reduce the noise by 10-20 decibels. This is the most economical low-noise valve.
Seven, use thick-walled pipeline method
The use of thick-walled tubes is one of the sound path treatment methods. The use of thin walls can increase the noise by 5 decibels, and the use of thick-walled tubes can reduce the noise by 0-20 decibels. 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, 21.5mm, the noise can be reduced to -3.5, -2 (that is, increase), 0, 3, 6, 8, 11, 13, 14.5 decibels. Of course, the thicker the wall, the higher the cost of the rotary lobe pumps.
8. Soundproof box method
Use soundproof boxes, houses and buildings to isolate the noise source inside, so that the noise of the external environment can be reduced to acceptable.