Description
F8011006A SMU1-1 Germany HIMA
F8011006A SMU1-1 Germany HIMA
Module Clips Drive controller servo motor
Contact: Mr. Lai
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Soundproof box method
Use speakers, houses, and buildings to isolate noise sources inside, reducing the noise in the external environment to an acceptable range for people.
7. Series throttling method F8011006A SMU1-1 Germany HIMA
In situations where the pressure ratio of the regulating valve is high (△ P/P1 ≥ 0.8), the series throttling method is used to disperse the total pressure drop between the regulating valve and the fixed throttling element behind the valve. Using diffusers and multi hole flow limiting plates is the most effective way to reduce noise. In order to achieve the best diffuser efficiency, it is necessary to design the diffuser (physical shape and size) based on the installation of each component, so that the noise level generated by the valve is the same as that generated by the diffuser.
8. Choose a low noise valve
The noise valve gradually decelerates according to the zigzag flow path (multi orifice, multi groove) of the fluid passing through the valve core and valve seat to avoid supersonic flow at any point in the flow path. There are various forms and structures of low noise valves (designed for specialized systems) available for use. When the noise is not very loud, choosing a low noise sleeve valve can reduce the noise by 10-20 decibels, which is the most economical low noise valve.
6、 5 Methods to Solve Poor Stability of Regulating Valves
1. Method of changing the direction of unbalanced force action F8011006A SMU1-1 Germany HIMA
In stability analysis, it is known that when the unbalanced force acts in the same direction as the valve closing, that is, when there is a tendency to close the valve, the valve stability is poor. When the valve operates under the above-mentioned unbalanced force conditions, the method of changing its direction of action is usually to change the flow closed type to the flow open type, which can easily solve the stability problem of the valve.
2. Method of avoiding unstable zone operation of the regulating valve itself
Some valves have poor stability when operating at certain opening angles due to their own structural limitations.
① Double seat valve with an opening of less than 10%, causing instability due to open flow at the upper ball and closed flow at the lower ball;
② The stability is poor near the area where the slope of the unbalanced force changes alternately. Like butterfly valves, the alternating point is around 70 degrees; The double seat valve has an opening of 80-90%. When encountering such valves, working in unstable areas inevitably results in poor stability, and avoiding working in unstable areas is sufficient.
3. Replace the valve with good stability
A valve with good stability has a small change in unbalanced force and good guidance. Among commonly used ball valves, sleeve valves have this major feature. When the stability of single or double seat valves is poor, replacing them with sleeve valves will definitely improve their stability.
4. Increase spring stiffness method
The ability of the actuator to resist the impact of load changes on the stroke depends on the spring stiffness. The greater the stiffness, the smaller the impact on the stroke, and the better the valve stability. Increasing spring stiffness is a common and simple method to improve valve stability, such as changing the spring range of 20-100KPa to a high stiffness spring of 60-180KPa. This method is mainly used for valves with locators, otherwise, the valves used need to be equipped with locators.
5. Reduce response speed method
When the system requires that the response or adjustment speed of the regulating valve should not be too fast, the response and adjustment speed of the valve are also fast. For example, if the flow needs to be fine tuned, but the flow adjustment change of the regulating valve is significant, or if the system itself is already a fast response system and the regulating valve is equipped with a locator to accelerate the valve”s action, this is unfavorable. This will result in overshoot, vibration, etc. To address this, the response speed should be reduced. The methods include:
① Change the flow characteristic of the regulating valve: change the linear characteristic to the logarithmic characteristic;
② The ones with locators can be changed to converters or relays.
7、 6 other problem-solving methods
1. Symmetrical tightening of bolts using thin gasket sealing method
In the structure of the “O” ring sealed regulating valve, when using thick gaskets with significant deformation (such as wound discs), if the compression is asymmetric and the force is asymmetric, it is easy to damage, tilt, and deform the seal, seriously affecting the sealing performance. Therefore, in the maintenance and assembly of such valves, it is necessary to symmetrically tighten the compression bolts (note that they cannot be tightened at once) . If a thick sealing gasket can be changed to a thin sealing gasket, it would be better to reduce the inclination and ensure sealing.
2. A method to increase the width of the sealing surface, prevent the jumping of the flat valve core when closed, and reduce its leakage
The flat valve core (such as the plug of a two-position valve or a sleeve valve) has no guiding or guiding surface inside the valve seat. When the valve is in operation, the valve core is subjected to lateral force, moving from the inlet side to the outlet side. The larger the clearance between the valve core and the valve core, the more severe this unilateral phenomenon is. In addition, deformation, non concentricity, or small chamfers on the sealing surface of the valve core (usually guided by a 30 ° chamfer) make it close to closure, The chamfered end face of the sealing surface of the valve core is placed on the sealing surface of the valve seat, causing the valve core to jump or even fail to close properly when closed, greatly increasing the leakage of the valve. The simplest and most effective solution is to increase the size of the valve core sealing surface, so that the minimum diameter of the valve core end face is 1-5mm smaller than the valve seat diameter, which has sufficient guiding effect to ensure that the valve core is guided into the valve seat and maintains good sealing surface contact.
3. Change the flow direction, solve the problem of promoting closure, and eliminate surge method
A two position valve is usually used as a flow closed type to improve the cutting effect. For liquid media, due to the unbalanced force of the flow closure type, the valve core is compressed and has a closing promoting effect, also known as suction effect, which accelerates the speed of the valve core action, produces a slight water hammer, and causes system surge. The solution to the above phenomenon is to simply change the flow direction to flow open, and the surge can be eliminated. Similar issues that affect the normal operation of the valve due to promoting closure can also be addressed by adopting this approach.
4. Overcoming fluid damage method
The most typical valve is a double seat valve, where fluid enters from the middle, the valve core is perpendicular to the inlet, and the fluid flows out in two bundles around the valve core. The fluid impacts the valve core, causing it to lean towards the outlet side, causing friction and damaging the guide surface of the valve core and liner, resulting in abnormal operation. High flow rates may also cause the valve core to bend, erode, and even break in severe cases. Solution:
① Improve the hardness of the guide material;
② Increase the size between the upper and lower balls of the valve core to make it appear thick;
③ Use other valves instead. If a sleeve valve is used, the fluid flows in from around the sleeve, greatly reducing the lateral thrust on the valve plug.
5. Method of overcoming the rotational force generated by the fluid to rotate the valve core
For the valve core of the “V” shaped port, due to the asymmetry of medium inflow, the tangential force acting on the valve core of the “V” shaped port is inconsistent, generating a rotational force that causes it to rotate. Especially for valves with DN ≥ 100, it is more intense. This may cause the valve to disconnect from the actuator push rod connection, and the spring free actuator may cause the diaphragm to twist. The solutions are:
① Rotate the valve core counterclockwise by an angle to balance the tangential force acting on the valve core;
② Further lock the connection between the valve stem and the push rod, and if necessary, add an anti rotation clamp plate;
③ Replace the valve core with a plunger shaped valve core with a V-shaped opening;
④ Adopting or changing to a sleeve structure;
⑤ If resonance causes rotation, eliminating resonance can solve the problem.
6. Adjust the friction force of the butterfly valve plate to overcome the opening and jumping method
Adopting “O” Butterfly valves with soft seals such as O-rings, sealing rings, and linings can achieve ideal shut-off effect when the valve is closed. Due to the deformation of the soft seal, the valve plate is closed in place and envelops the valve plate, which can achieve a very ideal shut-off effect. However, when the valve is to be opened, the force of the actuator to open the valve plate continuously increases. When the friction force between the soft seal and the valve plate is equal, the valve plate starts. Once started, this friction force decreases sharply. To achieve force balance, the valve plate is fierce When the unbalanced torque of the medium acting on the corresponding opening is balanced with the opening torque of the actuator, the valve stops at this opening. This violent and sudden jump opening can be as high as 30-50%, which will cause a series of problems. At the same time, due to significant changes in the soft sealing element during closure, it is easy to cause permanent deformation or be crushed or pulled by the valve plate, which affects the service life. The solution is to adjust the friction force of the soft seal on the valve plate during startup, which not only ensures the required cutoff, but also enables the valve to start normally. The specific methods include:
① Adjust the interference amount;
② By limiting or adjusting the pre tightening force and output force of the actuator, the difficulty of opening caused by excessive closing of the valve plate can be reduced.
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