Five solutions to external leakage of electric control valves

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　　When an electric control valve leaks during use, how should we deal with it? Here are five solutions to address leakage in electric control valves: The first solution is to use a lens gasket for sealing. For the sealing of the upper and lower covers, as well as between the valve seat and the upper and lower valve bodies, if a flat-seal design is used, the sealing performance is poor under high temperature and pressure, leading to leakage. Using a lens gasket with the electric control valve can yield satisfactory results. One of the five solutions to external leakage in electric control valves is to change the flow direction. The method of placing P2 at the valve stem end can be used; when △P is high and P1 is also high, sealing P1 is clearly more difficult than sealing P2. Therefore, electric control valves can employ the approach of changing the flow direction, by moving P1 to the valve stem end and P2 to the other end – this is particularly effective for valves that operate under high pressures and large pressure differences. For example, in bellows valves, it is usually necessary to focus on sealing P2. One of the five solutions to leakage in electric control valves is to increase the number of packing elements. Typically, a double-layer or multi-layer mixed packing system is used, with the simple increase in the number of sealing gaskets – for example, from 3 to 5 – in order to improve the sealing performance of the valve stem; however, this approach does not provide very effective leakage prevention in electric control valves. The method of adding sealing grease as one of the five solutions to external leakage in electric control valves: This approach is suitable for valve bodies that have not yet been fitted with sealing grease; by adding such grease, it is possible to improve the sealing performance of the valve stem. When performing regular maintenance on electric control valves, applying additional sealing grease is also one of the necessary maintenance procedures. One of the five solutions to external leakage in electric control valves is to replace the graphite packing. The widely used PTFE packing is suitable for operating temperatures in the range of -20 to 200°C; when the operating temperature varies significantly within this range, the sealing performance of the electric control valve deteriorates markedly, and it ages quickly with a short lifespan. It is recommended to use flexible graphite packing here, as it can overcome the difficulties that perfluoropolymer packing cannot handle, and it has a long service life, thereby improving the reliability of the seal. Many factories have completely replaced the PTFE packing with graphite packing, and even newly purchased control valves have their PTFE packing replaced with graphite packing before use. However, graphite fillers also have a drawback: they exhibit a large hysteresis, and in some cases crawling phenomena occur as well. Therefore, manufacturers and users must take this into consideration when designing and installing electric control valve systems. 　　The five solutions mentioned above for leaks in electric control valves are intended to provide some assistance to manufacturers and users of such valves when dealing with leakage issues.