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:

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.

High-frequency vibration is caused by the excitation frequency consistent with the natural frequency of the valve and the medium flow, leading to resonance in hydraulic control valves. This noise is mainly due to the pressure reducing valve's inadequate design. To reduce mechanical vibration noise, it is essential to design the pressure reducing valve liner and stem clearance, improve machining accuracy, adjust the natural frequency of the valve and the rigidity of moving parts, and select materials correctly.

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.

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.

Cavitation noise refers to the phenomenon where, during the pressure reduction process of a pressure reducing valve, when the fluid flow rate reaches a certain value, the liquid will start to vaporize. When the pressure of the bubbles in the liquid reaches a certain level, they will burst, generating a high-pressure shock wave in the local area. This shock wave, with an instantaneous pressure of up to 196 MPa at the self-regulating valve, is a significant factor leading to pressure reducing valve cavitation and noise. To reduce mechanical vibration noise, it is essential to design the pressure reducing valve in a way that keeps the pressure below the critical value and preferably below the initial pressure drop (Δp initial). If the pressure reduction value of the pressure reducing valve reaches the Δp initial value, cavitation will occur, leading to a sharp increase in noise. Additionally, when using a self-operated control valve, attention must be paid to the direction of fluid flow relative to the valve disc.

Third, aerodynamic noise

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