Regulating valve gate leakage fault handling methods
Electric control valve with its advantages of high control precision, easy installation and debugging in a variety of industrial control system has been more and more widely used. But, in use process, there are also some problems with the field instruments, is valve gate leakage problem. Here we will explore the common causes of leakage of electric regulating valve and solution, hoping to on-site maintenance personnel to the factory have a little help. 1, the executing agency zero set is not accurate, not reached the seated position of the valve gate. Adjust way: 1) Closing the valve manually ( Must be confirmed completely shut down) ; 2) Reoccupy force close the valve manually, but use a strength twist fixed shall prevail; 3) Turn back again, Open the valve direction) Half a circle; 4) And then adjust the limit. 2, the valve door is pushed down closed type, thrust of the actuator is not big enough, in the absence of pressure debugging is easy to achieve, fitted with thrust, cannot overcome liquid upward thrust, so does not reach the designated position. Solution: replace the big thrust actuator, or the type to balance valve core to reduce the unbalanced force of medium. 3, electric regulating valve manufacturing quality caused by the leak valve door manufacturer is in manufacturing process of the valve door material, processing technology and assembly process control is lax, the sealing surface grinding is unqualified, the pitting, products are not completely eliminate defects such as trachoma, caused in the electric control valve gate leakage. Solution: reprocessed seal face. Part 4, electric regulating valve control effects of leakage of valve door electric regulating valve of the traditional control mode is through threshold position switch, a torque switch valve control mode of the machinery, as a result of these control element is affected by environmental temperature, pressure, humidity, causing the valve gate location phrase, spring fatigue, thermal expansion coefficient of inhomogeneous objective factors, such as electric regulating valve leakage. Solution: adjust the limit again. 5, electric regulating valve debugging problem caused by the leakage because of the influence of processing and assembly process, electric regulating valve are widespread manually locked after electric wouldn't open phenomenon, such as motion through the upper and lower limit switch position adjust the electric valve stroke adjustment of smaller, electric regulating valve in lax or valve door open exhibition is not ideal; The electric regulating valve stroke adjustment, the cause of torque switch protection action; If the adjustment of torque switch action value, reduction drive crashed in institutions or damaged valve door, and even to the motor burned accident. In order to solve this problem, usually, electric regulating valve commissioning manual valves to regulate the electric wave to the end, to open a circle, again set the lower limit of the electric door switch position, and then puts the electric regulating valve to full open position limit switch position, won't appear such electric regulating valve manually locked after electric wouldn't open phenomenon, to make the electric door open and close operation freely, but virtually caused the electric gate leakage. Even electric regulating valve adjustment is more ideal, because of the limit switch action position is relatively fixed, in the operation of the valve gate control medium in the valve door of scour, wear, can also cause the valve door closed lax and cause of leakage phenomenon. Solution: adjust the limit again. 6, selection error caused by the valve door of cavitation corrosion electric regulating valve leakage cavitation related to pressure difference, when the actual pressure differential valve door delta P is greater than produce cavitation critical pressure differential delta Pc, will produce cavitation, in the process of cavitation bubbles burst release enormous energy, the valve seats, valve core is an enormous damage, the throttling components such as general valve door under the condition of cavitation run no more than three months, or even shorter time, namely the valve door suffered severe cavitation corrosion, high leakage in the valve seat can reach more than 30% of the rated flow, this is irreparable, therefore, different USES electric door has different specific technical requirements, according to system process to choose reasonable electric regulating valve is very important. Solution: process improvement, choose multi-stage decompression or sleeve valve adjustment. 7, medium scour, electric regulating valve leakage caused by aging electric regulating valve adjust after a certain time after the operation, as a result of the valve gate cavitation and dielectric flushing, the valve core and valve seat wear, internal components aging causes, electric regulating valve stroke will appear larger, electric regulating valve is lax phenomenon, cause the electric regulating valve leakage quantity is big, with the passage of time, the electric control valve gate leakage phenomenon will be more and more serious. Solution: adjust the actuators, and regular maintenance, calibration.