Regulating valves play an important role in the automat […]
Regulating valves play an important role in the automatic control of modern factories, and the production of these factories depends on the correct distribution and control of the flowing medium. These controls, whether it is energy exchange, decompression or simple container feeding, require some final control components to complete. The regulating valve belongs to the control valve series. The main function is to adjust the pressure, flow, temperature and other parameters of the medium, which is the final control component in the process loop.
How to solve the problem of electric control valve leakage
1) Method to increase sealing grease
For electric control valves that do not use sealing grease, please consider adding sealing grease to improve the sealing performance of the valve stem.
2) Add filling method
In order to improve the sealing performance of the packing to the valve stem, a method of adding packing can be used. Usually, it is in the form of two-layer, multi-layer mixed filler, which will only increase the quantity. For example, if you increase 3 pieces to 5 pieces, the effect is not obvious.
3) Replace graphite packing method
PTFE filler is used in a large amount because its working temperature is in the range of -20 to 200°C. When the temperature changes between the upper and lower limits, the sealing performance is significantly reduced, the aging is fast, and the life is short. Flexible graphite filler overcomes these shortcomings and has a long service life. Therefore, some factories have changed PTFE packing to graphite packing, and even newly purchased regulating valves have replaced PTFE packing with graphite packing. However, the use of graphite fillers has a large backlash, and some of them also have creep phenomena at the beginning, which must be considered.
4) Change the flow direction, set P2 in the stem end method
When ΔP is larger and P1 is larger, the seal P1 is obviously more difficult than the seal P2. Therefore, the method of changing the flow direction can be adopted, and the P1 is changed to the P2 end at the end of the valve stem, which is higher in pressure and pressure difference. Large valves are more effective. For bellows valves, seal P2 should normally be considered.
5) Use lens pad sealing method
In order to seal the upper and lower covers, the valve seat is sealed with the upper and lower valve bodies. If it is a flat seal, the sealing performance is poor under high temperature and high pressure, resulting in leakage, so a lens pad seal can be used instead, and satisfactory results can be obtained.
6) Replace the gasket
So far, most sealing gaskets still use asbestos plates. At high temperatures, the sealing performance is poor and the service life is short, leading to leakage. In this case, you can use spiral wound gaskets, "O" rings, etc., which are now used in many factories.