High Noise of Control Valves

a. Noise generated by mechanism vibration. Elimination methods: Maintain tight radial clearance between valve plug and sleeve; adopt sleeves with hard surfaces to prevent clearance enlargement; equip valve plugs of sleeve valves with heavy-duty guides by extending and enlarging guiding surfaces to disperse impact load and suppress vibration.

b. Noise caused by natural frequency vibration. Elimination methods: Use integrated valve core components to break structural symmetry; replace valve core types, such as changing cylindrical thin-wall window cores to plunger cores; increase valve core diameter or adjust medium flow direction; employ single-seat valves with heavy-duty valve core guidance.

c. Noise induced by unstable throttling. Unstable vibration mainly arises from alternating unbalanced medium force acting on the valve core. Solutions: Select actuators with wide spring ranges; install pulse dampers or vibration absorbers on actuator push rods; choose valves with low unbalanced force and high stability including cage single-seat valves, angle valves and balanced cage valves under process requirements; adopt flow-opening type for control valves with seat diameter larger than stem diameter; equip electro-pneumatic converters to avoid overshoot in fast response systems, and select equal-percentage flow characteristics.

d. Noise triggered by medium flow. Cavitation suppression is an effective measure. Specific measures: Apply valve internals with multiple high-speed flow ports to operate at high frequency and accelerate noise attenuation via valve body inner walls; adopt sharp-edged internals to alter flow pattern and reduce flow velocity and vortex scale; use expansive materials for internals for vibration damping; apply sound insulation and absorption materials.

e. Noise from other factors. Severe noise occurs when pressure ratio reaches. Series throttling is applicable to distribute total pressure drop between the control valve and downstream fixed throttling components such as diffusers and porous restrictor plates. The shape and size of diffusers shall be designed according to actual installation conditions for optimal performance.