Spring type safety valve refers to that the valve or plunger seal of the valve is locked by the elastic pressure of the spring. The spring type safety valve should be installed vertically. When the pressure of the pressure vessel is abnormal, the high pressure will overcome the spring pressure of the safety valve, so the locking device is jacked open to form a pressure relief channel to release the high pressure. There should be no resistance at the outlet of safety valve to avoid pressure phenomenon. In the process of using, the faults of spring type safety valve are mainly as follows:
1. The valve disc always beats or vibrates
The main reason is that the spring hardness is too large. The spring with suitable hardness should be used, and improper adjustment of adjusting ring will make the recoil force too high. At this time, the position of the adjusting ring should be readjusted; the discharge pipe resistance is too large, resulting in excessive discharge back pressure. The discharge pipe resistance should be reduced.
Under normal equipment pressure, more than allowable leakage occurs between the disc and seat seal gap because of dirt between the two. At this time, the lift wrench should be used to open the valve repeatedly for several times to flush out the dirt; according to the degree of damage, the grinding method after grinding or turning is used to repair; the valve stem is bent, inclined or the lever and fulcrum are skewed, so that the valve core and valve disc are misaligned. It should be reassembled or replaced; the elasticity of spring is reduced or lost. The spring should be replaced and the opening pressure should be readjusted.
3. It can’t be opened when it reaches the specified pressure
It can’t be opened because the constant pressure is not accurate. The compression of the spring or the position of the heavy hammer should be readjusted; the valve disc is stuck with the valve seat. Manual air release or water discharge test shall be conducted regularly for safety valve; lever of lever type safety valve is stuck or heavy hammer is moved. The position of the heavy hammer should be readjusted and the lever can move freely.
4. The pressure continues to rise after exhaust
This is mainly because the selected safety valve displacement is small, and the safety discharge capacity of the flat equipment should be re selected; if the center line of the valve stem is not correct or the spring is rusty, so the valve disc can not be opened to the proper height, the valve stem should be reassembled or the spring should be replaced; if the exhaust pipe is not cut enough, the exhaust pipe meeting the safety discharge area should be taken.
5. Valve disc does not return to seat after discharge
This is mainly due to the spring bending, valve stem, valve disc is not in the correct position or stuck, should be re assembled.