Causes of pressure reducing valve noise

Causes of pressure reducing valve noise

The causes of noise from pressure reducing valves can be divided into three main categories as follows:

Mechanical vibration noise

Pressure reducing valve parts in the fluid flow pneumatic control valve will produce mechanical vibration, mechanical vibration can be divided into two forms:

① low-frequency vibration. Low-frequency vibration. This vibration is caused by the jet and pulsation of the medium, the cause of which lies in the valve outlet of the flow rate is too fast, the piping arrangement is unreasonable and the valve activity parts of the rigidity is insufficient.

② high-frequency vibration. This vibration in the valve's natural frequency and medium flow caused by the excitation frequency is consistent, hydraulic control valves will cause resonance, it is a pressure reducing valve in a certain range of pressure reduction, and once the conditions change slightly, the noise change is very large. This mechanical vibration noise has nothing to do with the medium flow rate, mostly due to the pressure reducing valve itself is not reasonable design. Measures to reduce mechanical vibration noise is to reasonably design the pressure reducing valve liner and stem clearance, machining accuracy, the natural frequency of the valve and the rigidity of the moving parts, the correct choice of materials.

Second, fluid dynamic noise

Fluid dynamics noise is generated by the turbulence and vortex after the fluid passes through the pressure reducing port of the pressure reducing valve, and the process of its generation can be divided into two stages:

① turbulent noise, that is, by the turbulent fluid and pressure reducing valve or pipe surface interaction and noise, its frequency and noise level are relatively low, generally does not constitute a noise problem.

② cavitation noise, that is, pressure reducing valve in the pressure reduction process, when the fluid flow rate reaches a certain value, the fluid (liquid) will begin to vaporize, when the pressure of the bubbles in the liquid reaches a certain value, it will explode. Bubbles in the explosion, to produce a very high pressure and shock wave in the local area, self-regulating valve this shock instantaneous pressure of up to 196 MPa, but away from the center of the explosion, the pressure attenuated sharply. This shock wave is a major factor causing pressure reducing valve cavitation and noise. Measures to reduce mechanical vibration noise is in the design of the pressure reducing valve, the pressure reducing valve must be controlled below the critical value of the pressure reducing valve, and, preferably, below the Δp initial, because the actual pressure reducing valve pressure reduction value to reach the Δp initial value, the liquid will begin to produce cavitation, and the noise will be sharply increased. Self-operated control valve in addition, but also pay attention to the direction of flow of the fluid medium relative to the valve flap.

Third, aerodynamic noise

When steam and other compressible fluids through the pressure reducing parts of the pressure reducing valve, the mechanical energy of the fluid is converted to acoustic energy and produce In summary, fundamentally, the pressure reducing valve noise are related to their own design and manufacturing process.