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The electric regulating valve is a special valve that adjusts the flow of the medium. The valve automatically controls the opening of the valve according to the measured parameters (such as temperature, pressure, flow, etc.), with the purpose of keeping the measured parameters constant.It is precisely because of the precise adjustment function of the electric control valve that the internal leakage of the valve becomes the weakness of such products.
The following introduces several treatment methods for internal leakage of the regulating valve.
1. The zero position setting of the actuator is inaccurate, and the fully closed position of the valve is not reached.
Adjustment method:
1) Close the valve manually (it must be confirmed that it has been completely closed);
2) Manually close the valve again with a little force;
3) Screw it back (in the direction of valve opening) for half a turn;
4) Then adjust the limit.
2. The valve is a push-down closing type. The thrust of the actuator is not large enough. When there is no pressure, it is easy to reach the fully closed position. When there is a downward thrust, it cannot overcome the upward thrust of the liquid, so the closing is not in place.
Solution: Replace the actuator with high thrust, or change it to a balanced spool to reduce the unbalanced force of the medium.
3. Internal leakage caused by the manufacturing quality of the electric regulating valve. The valve manufacturer does not strictly control the valve material, processing technology, assembly technology, etc. in the production process, resulting in unqualified sealing surface grinding, and no products with defects such as pitting and trachoma. Completely eliminated, resulting in internal leakage of the electric regulating valve.
Solution: Rework the sealing surface.
4. The control part of the electric control valve affects the internal leakage of the valve. The traditional control method of the electric control valve is through mechanical control methods such as valve limit switches and over-torque switches. Since these control components are affected by ambient temperature, pressure and humidity, Cause valve positioning inaccuracy, spring fatigue, uneven thermal expansion coefficient and other objective factors, resulting in internal leakage of the electric control valve.
Solution: Readjust the limit.
5. The internal leakage caused by the debugging problem of the electric control valve is affected by the processing and assembly process, and the electric control valve generally has the phenomenon that the electric control valve cannot be opened electrically after it is manually closed. If the stroke of the electric control valve is adjusted to be smaller through the action position of the upper and lower limit switches, the electric control valve will not be closed tightly or the valve will not be opened. The torque switch protects the action; if the action value of the over-torque switch is adjusted to a larger value, there will be accidents such as hitting the deceleration transmission mechanism or hitting the valve, or even burning the motor. In order to solve this problem, usually, when debugging the electric control valve, manually shake the electric control valve to the end, and then shake it in the opening direction to set the lower limit switch position of the electric door, and then open the electric control valve to the fully open position to set the upper limit. The switch position, so that the electric regulating valve will not have the phenomenon that the electric valve cannot be opened electrically after it is manually closed, so that the electric door can be opened and closed freely, but it will cause the electric door to leak. Even if the adjustment of the electric control valve is ideal, because the action position of the limit switch is relatively fixed, the medium controlled by the valve will continue to scour and wear the valve during operation, which will also cause internal leakage caused by the valve is not closed tightly.
Solution: Readjust the limit.
6. The cavitation corrosion of the valve caused by the wrong type selection causes the internal leakage of the electric control valve. The cavitation is related to the pressure difference. When the actual pressure difference △P of the valve is greater than the critical pressure difference △Pc that produces cavitation, cavitation occurs. In the process of cavitation, when the bubble bursts, it releases huge energy, which has a huge destructive effect on throttling components such as valve seat and valve core. Generally, the valve operates for three months or even less time under cavitation conditions, that is, the valve Suffered from severe cavitation corrosion, the leakage of the valve seat can reach more than 30% of the rated flow. Reasonable selection of electric regulating valve is very important.
Solution: Carry out process improvement and choose multi-stage pressure-reducing or sleeve regulating valve.
7. The internal leakage caused by the scouring of the medium and the aging of the electric regulating valve, after the electric regulating valve is adjusted and running for a certain period of time, due to the cavitation of the valve and the scouring of the medium, the wear of the valve core and the valve seat, and the aging of the internal components, etc. , there will be a phenomenon that the stroke of the electric control valve is too large and the electric control valve is not tightly closed, resulting in a larger leakage of the electric control valve. As time goes by, the leakage of the electric control valve will become more and more serious.
Solution: readjust the actuator, and perform regular maintenance and calibration.
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