Electric control valve is an important execution unit meter in industrial automation process control. With the increasing degree of automation in the industrial field, more and more applications are being made in various industrial production fields. However, in the course of use, we often encounter the failure of the electric control valve leakage, then, how to deal with it?
1, increase the sealing oil method
For valves that do not use sealed grease, consider adding sealant grease to improve stem seal performance.
2, increase the filling method
In order to improve the sealing performance of the packing on the stem, a method of increasing the filling may be used. Usually double-layered or multi-layered mixed fillers are used. Simply increasing the number, such as increasing 3 to 5, is not effective.
3, replace the graphite packing method
The PTFE filler used in large quantities, because of its operating temperature in the range of -20 ~ 200 °C, when the temperature in the upper and lower limits, a large change, its sealing will be significantly reduced, aging fast, short life. Flexible graphite fillers overcome these shortcomings and have a long service life. As a result, some plants have changed their PTFE fillers to graphite fillers, and even the newly purchased control valves have been replaced with graphite fillers. However, the difference in the use of graphite fillers is large, and some creeping phenomenon occurs at the beginning, which must be taken into consideration.
4, change the flow, set P2 in the stem end method
When ΔP is large and P1 is large, the seal P1 is obviously more difficult than the seal P2. Therefore, the method of changing the flow direction may be adopted. The P1 is changed from the stem end to the P2 end of the stem, and the pressure is high and the pressure difference is high. Larger valves are more effective. For example, bellows valves should normally be considered sealed P2.
5, using lens gasket sealing method
For the upper and lower cover seals, the valve seat and the upper and lower valve body seal. If the plane seal, under high temperature and high pressure, poor sealing, causing leakage, you can use the lens pad seal, can get satisfactory results.
6, replace the gasket
To date, most gaskets still use asbestos plates, which have poor sealing performance and short life at high temperatures, causing leakage. In this case, wound gaskets, "O" rings, etc., can be used instead, and many plants have already adopted them.