Common faults and elimination methods for safety valves
After the safety valve is installed, it often causes many failures due to improper use. If these faults are not eliminated in time, the function and service life of the safety valve will be affected. Common faults are mainly:
(1) The valve flap does not return to the seat after discharge
This is mainly caused by the spring-bending valve stem, the valve flap is not installed properly, or is stuck. Should be reassembled.
(2) Leakage
Under the normal working pressure of the equipment, leakage exceeding the allowable degree occurs between the valve flap and the seat sealing surface. The reason is that there is dirt between the valve flap and the sealing surface of the valve seat. The valve can be opened several times with a lift wrench to flush the dirt; the sealing surface is damaged. It should be repaired by grinding or grinding after grinding according to the degree of damage; the stem is bent, tilted or the lever and the fulcrum are skewed, so that the valve core and the valve disc are misaligned. Should be reassembled or replaced; the spring elasticity is reduced or loses its elasticity. Measures such as replacing the spring and re-adjusting the opening pressure should be taken.
(3) Do not open when the pressure is specified
The reason for this is that the pressure is not accurate. The amount of compression of the spring or the position of the weight should be readjusted; the disc is stuck to the seat. The safety valve should be manually deflated or drained periodically; the lever of the lever safety valve is stuck or the weight is moved. The weight position should be re-adjusted and the lever moved freely.
(4) The pressure continues to rise after exhaust
This is mainly because the safety relief valve of the selected safety valve displacement device should be re-selected with a suitable safety valve; the center line of the valve stem is not correct or the spring is rusted, so that the valve flap cannot be opened to the proper height, and the valve stem should be reassembled. Or replace the spring; if the exhaust pipe is not enough, take the exhaust pipe that meets the safe discharge area.
(5) flap frequency jump or vibration
Mainly due to the spring stiffness is too large. Should use the appropriate stiffness of the spring; improper adjustment of the adjustment ring, so that the return pressure is too high. The position of the adjustment ring should be readjusted; the resistance of the discharge pipe is too large, causing excessive discharge back pressure. The discharge pipe resistance should be reduced.
(6) Open below the specified pressure
Mainly the fixed pressure is not allowed; the spring aging elasticity decreases. The adjusting screw or the spring should be properly tightened.
