Cavitation and noise are two of the most common hazards of regulating valves in controlling high differential pressure fluids. Regulating valve noise is the main source of pollution in the petrochemical industry. In addition to the use of low-noise structure in the selection of the control valve, the valve operating conditions change is to eliminate or reduce cavitation and noise, the fundamental method. Regulating valve in the work, should pay attention to its noise situation, analysis of the noise generation mechanism can better monitor the working status of the valve and effectively handle the problems that occur. (1) Mechanical vibration - When the spool moves horizontally in the sleeve, the clearance between the spool and the sleeve can be minimized or the sleeve with hard surface can be used. (2) Natural Frequency Vibrations - such as spools or other components all have an inherent vibrational frequency for which the characteristics of the spool can be changed by special casting or forging treatment, and other types can be changed if necessary The spool. (3) Spool instability - such as noise caused by pressure fluctuations of the fluid due to oscillating displacement of the spool, is usually caused by damping factors such as the actuator of the regulating circuit, for which the damping can be readjusted Coefficient or in the spool displacement direction plus damping facilities. (4) Mechanical fluidity of media - The media also emits noises when it flows in pipes or regulating valves. This is not explained in detail here (cavitation can also cause noise).