What is causing the regulator of vibration and noise

In production, we sometimes find regulating valve, relief valve and other valve produce serious vibration and noise. Actually generate vibration and noise at the same time, the valve of the valve core and valve seat is serious erosion, such as interior parts produced series grinding crack, deep groove and potholes, or even cause stem fracture, the use of these have seriously affected the valve performance, reduce the service life. Regulator of vibration and noise according to the induced factors, can be roughly divided into mechanical vibration, cavitation and fluid ( Eddy current) Vibration and other reasons. Factors causing vibration and noise of cavitation cavitation vibration generally occur within the regulating valve in liquid media. The fundamental cause of cavitation is contracted flow regulator within the fluid acceleration and static pressure drop of liquid. Before and after the valve opening is smaller, the pressure difference, the greater the flow speed and the greater the likelihood of cavitation, and the matching block the flow and the smaller the pressure drop. Mechanical vibration mechanical vibration according to its form of expression can be divided into two states. A state is a regulator of the overall vibration, namely the regulator in the pipe or fibrillation frequently, the reason is because the pipeline or base violent vibration, vibration caused the regulator. Also related to the frequency, that is, when the frequency of the external and the system is equal or close to the natural frequency of forced vibration energy reached maximum, produce resonance. Another state is the vibration of the regulator valve, the main reason is due to the rapid increase of medium velocity, the regulating valve before and after the differential change sharply, cause the regulator to produce severe oscillation. Vortex vibration fluid within the valve throttle, due to the friction, resistance and disturbance of various factors, this inevitably produces a wide variety of vortex flow, such as fluid impact stem, through gaps and turn at the corner, and the shunt, have vortex flow, vortex flow and cylinder interaction, induced vibration, which from the sound. Once the air vibration frequency of the coupled with the natural frequency of vibration of the mechanical components, or with the pipe transverse and longitudinal column acoustic standing wave column oscillation, dynamic impact, gas dynamic compression or other unstable flow pressure wave coupling, vibration, noise increases. If the fluid flows through the control valve flash can form there are bubbles of gas and liquid two phase mixture, two-phase fluid noise reduction and expansion effect also can form. In addition, the empty into unavailable, release a powerful energy bubble burst, can produce up to 10000 hz noise, air bubble, the more the more serious the noise. How to deal with the vibration and noise for cavitation small open degree of work should be avoided in the first place. The valve opening is too small, the throttling inlet velocity increase, pressure decrease rapidly, fluid flow through the valve is easy to form a flash and air corrosion. Instrument and meter plant 'click here' mentioned in this article the valve small open degree of the damage cause cavitation, we must not neglect. The second distribution of multistage pressure drop should be adopted. To prevent the occurrence of cavitation is the most effective way is to make the valve pressure drop is less than the cavitation occurred at all levels within the minimum differential pressure, the critical pressure is poor. When the control valve to withstand pressure difference is far greater than the critical pressure difference, the structure of multi-stage decompression can be used. In the design of multistage throttle valve, the throttling on the differential pressure to make each level is less than the allowed pressure difference, so that each level are part of the energy consumption, making the next level of the population pressure is relatively low, reduced the level of differential pressure, low pressure recovery, which can reduce the velocity of throttle position, avoid the generation of cavitation and reduce the effect of cavitation. Of course, if the working condition of the system is unfavorable in multi-stage decompression structure, the structure of the throttle sleeve may be adopted. In the end, should be planning reasonable driving technology. Drive of manufacturing process is very important to the usage of regulating valve, for higher working pressure and low pressure difference before and after regulating valve. In view of the mechanical vibration should first choose right parts. If the disc rapid change of high and low, valve positioner and high sensitivity, a slight variation in the regulator output or drift, locator will converted into output signal is very large, the valve oscillations. Regulator of the friction force is too small, the input signal is small changes or drift, immediately passed to the disc, make its vibration. Instead, such as the regulator of the friction is too big, the action in the small signal without the large signal at the phenomenon of movement and produce too much, will make the regulator produces hysteresis oscillation. Encounter this kind of situation, should reduce the regulator to solve the corresponding part of the damping, such as replacement of packing, etc. The second stem connection should be paid attention to. In the process of some process for normal operation of the unit, high temperature and high pressure steam continuously through high pressure gate valve core, cause high pressure gate valve core and valve stem between torque, thus the spinor shear pin, tone and the cause of the bearing vibration, the cylindrical pin are badly affected, until the fracture damage, high pressure gate valve stem falls off, threats to its safe, if repair improper will leave a great safety hidden trouble. Finally, the control valve installation position should be far away from the vibration source, such as inevitable, preventive measures should be taken. For eddy current for eddy current, first should use the appropriate interval, small meanders trims. When the fluid flows through a small aperture with the proper spacing sleeve or other indirect pathway, can obtain the smaller jet flow volume, and thus reduce the eddy current volume, reduce the efficiency of the conversion between mechanical energy and acoustic, and effectively reduce the vibration and noise.