1. Increase stiffness

For oscillations and slight vibrations, the stiffness can be increased to eliminate or weaken it. For example, using a spring with a large stiffness or using a piston actuator is feasible.

2. Increase damping

Increasing damping means increasing friction against vibration. For example, the valve plug of a sleeve valve can be sealed with an “O” ring, or graphite filler with large friction, which can play a certain role in eliminating or weakening slight vibrations.

3. Increase the guide size and reduce the fit gap

The guide size of shaft plug valves is generally small, and the matching clearance of all valves is generally large, ranging from 0.4 to 1 mm, which is helpful in generating mechanical vibration. Therefore, when slight mechanical vibration occurs, the vibration can be weakened by increasing the guide size and reducing the fitting gap.

4. Change the shape of the throttle to eliminate resonance

Because the so-called vibration source of the regulating valve occurs at the throttle port where high-speed flow and pressure change rapidly, changing the shape of the throttle member can change the frequency of the vibration source, which is easier to solve when the resonance is not strong.

The specific method is to turn the curved surface of the valve core by 0.5~1.0mm within the vibration opening range. For example, a self-operated pressure regulating valve is installed near the family area of a factory. The whistling sound caused by resonance affects the rest of employees. After the valve core surface is turned away by 0.5mm, the resonance whistling sound disappears.

5. Replace the throttling part to eliminate resonance

The methods are:

Change the flow characteristics, logarithmic to linear, linear to logarithmic;

Replace the valve core form. For example, change the shaft plug type to a “V”-shaped groove valve core, and change the shaft plug type of a double-seat valve to a sleeve type;

Change the window sleeve to a sleeve with small holes, etc.

For example, a DN25 double-seat valve in a nitrogen fertilizer plant often vibrated and broke at the connection between the valve stem and the valve core. After we confirmed that it was resonance, we changed the linear characteristic valve core to a logarithmic valve core, and the problem was solved. Another example is a DN200 sleeve valve used in a laboratory of an aviation college. The valve plug rotated strongly and could not be put into use. After changing the sleeve with a window to a sleeve with a small hole, the rotation immediately disappeared.

6. Change the type of regulating valve to eliminate resonance

The natural frequencies of regulating valves with different structural forms are naturally different. Changing the type of regulating valve is the most effective way to fundamentally eliminate resonance.

The resonance of a valve is very severe during use – it vibrates strongly (in severe cases, the valve can be destroyed), rotates strongly (even the valve stem is vibrated or twisted), and produces strong noise (up to more than 100 decibels). Just replace the valve with a valve with a larger structural difference, and the effect will be immediate, and the strong resonance will miraculously disappear.

For example, a DN200 sleeve valve is selected for the new expansion project of a vinylon factory. The above three phenomena exist. The DN300 pipe jumps, the valve plug rotates, the noise is more than 100 decibels, and the resonance opening is 20 to 70%. Consider the resonance opening. The degree is large. After using a double-seat valve, the resonance disappeared and the operation was normal.

7. Method to reduce cavitation vibration

For the cavitation vibration caused by the collapse of cavitation bubbles, it is natural to find ways to reduce cavitation.

The impact energy generated by bubble bursting is not acted on the solid surface, especially the valve core, but is absorbed by the liquid. Sleeve valves have this feature, so the shaft plug type valve core can be changed to a sleeve type.

Take all measures to reduce cavitation, such as increasing throttling resistance, increasing constriction orifice pressure, staged or series pressure reduction, etc.

8. Avoid vibration source wave attack method

Wave shock from external vibration sources causes valve vibration, which is obviously something that should be avoided during normal operation of the regulating valve. If such vibration occurs, corresponding measures should be taken.