1. INCREASE THE STIFFNESS METHOD
For oscillation and slight vibration, the stiffness can be increased to eliminate or weaken. For example, it is feasible to use a spring with a large stiffness and a piston actuator.
2. INCREASE THE DAMPING METHOD
Increasing the damping increases friction against vibration. For example, the valve plug of the sleeve valve can be sealed with an “O” ring, and a graphite filler with a large frictional force is used, which has a certain effect on eliminating or attenuating a slight vibration.
3. INCREASE THE GUIDE SIZE, REDUCE THE FIT GAP METHOD
Shaft plug valves generally have small guide sizes, and all valve fit clearances are generally large, 0.4 to 1 mm, which is helpful for generating mechanical vibration. Therefore, when a slight mechanical vibration occurs, the vibration can be weakened by increasing the guide size and reducing the fit clearance.
4. CHANGE THE SHAPE OF THE THROTTLE, ELIMINATE THE RESONANCE METHOD
Because the so-called vibration source of the control valve occurs in the throttle port with high speed and sudden change of pressure, changing the shape of the throttle member can change the frequency of the vibration source, and it is relatively easy to solve when the resonance is not strong. The specific method is to cut the surface of the valve core in the range of vibration opening by 0.5~1.0mm. If a self-operated pressure control valve is installed around a manufacturer’s area, the whistle will affect the rest of the staff due to resonance, we will use the valve core curved car. After falling 0.5mm, the resonance whistling sound disappeared.
5. REPLACE THE THROTTLE TO ELIMINATE THE RESONANCE METHOD
The methods include: 1 changing the flow characteristics, linearly changing the logarithm, linearly changing the logarithm; 2 replacing the spool form. If the shaft plug shape is changed to a “V”-shaped groove valve core, the double seat valve shaft plug type is changed into a sleeve type; the open window sleeve is changed to a small hole sleeve. For example, if a DN25 double seat valve of a nitrogen fertilizer plant, the connection between the valve stem and the valve core often breaks, we think that after the resonance, the linear characteristic valve core is changed to the logarithmic valve core, and the problem is solved. Another example is the use of a DN200 sleeve valve in an aeronautical laboratory. The valve plug is strongly rotated and cannot be used. When the sleeve of the open window is changed to the sleeve of the small hole, the rotation disappears immediately.
6. REPLACE THE REGULATOR TYPE TO ELIMINATE RESONANCE.
Different types of control valves have different natural frequencies, and replacing the control valve type is the most effective way to fundamentally eliminate resonance. A valve resonates very strongly in use—strongly vibrating (destroying the valve in severe cases), rotating strongly (even the stem is broken, twisted), and producing strong noise (up to 100 decibels) The valve, as long as it is replaced by a valve with a large difference in structure, immediately works, and the strong resonance disappears miraculously. For example, a new DN200 sleeve valve is selected for the new expansion project of a Vinylon plant. The above three phenomena exist. The DN300 pipe will jump, the valve plug will rotate, the noise will be more than 100 decibels, and the resonance opening will be 20-70%. Consider the resonance opening. When the degree is large, after switching to a double seat valve, the resonance disappears and the operation is normal.
7. REDUCE CAVITATION VIBRATION METHOD
For cavitation vibrations caused by the cavitation bubble collapse, it is natural to find ways to reduce cavitation. 1 The impact energy generated by the rupture of the bubble does not act on the solid surface, especially on the valve core, but allows the liquid to absorb. The sleeve valve has this feature, so the plug type spool can be changed to a sleeve type. 2 Take all measures to reduce cavitation, such as increasing throttling resistance, increasing the pressure at the contraction port, decompression in series or series.
8. AVOID THE VIBRATION SOURCE WAVE STRIKE METHOD
The external source vibration causes the valve to vibrate, which is obviously avoided when the control valve works normally. If such vibration is generated, corresponding measures should be taken.