How to adjust the discharge pressure and return pressure of the Dewar safety valve?

First of all, we must understand what is the discharge pressure of the safety valve of the Dewar bottle and what is the return pressure of the safety valve. The discharge pressure of the Dewar safety valve is the pressure on the inlet side when the valve disc reaches the specified opening height. The back-seat pressure is the inlet pressure when the valve disc re-presses the valve seat after the safety valve is discharged, and the medium stops discharging. The following is the explanation of how to adjust the discharge pressure and return pressure of the safety valve and related precautions by the technicians of Jianshen tank.

How to adjust the discharge pressure and return pressure of the safety valve?
1. The safety valve should be subjected to pressure test and air tightness test before installation to check the strength and sealing performance of the safety valve. Calibration and adjustment can only be carried out after it is qualified.

2. On the gas test bench, correct the opening pressure of the safety valve by adjusting the load imposed on the control valve disc. The lever type safety valve adjusts the position of the weight, and the spring type safety valve adjusts the spring compression. The opening pressure of the safety valve should comply with the relevant regulations of the boiler and pressure vessel safety technical supervision regulations. 3. On the container, adjust the discharge pressure and return pressure of the safety valve by adjusting the gap between the safety valve adjusting ring and the valve disc. If the safety valve only leaks under the opening pressure and does not take off, or although it takes off but there is severe vibration and "buzzing" after the pressure drops, the gap is too large and should be adjusted smaller. If the return pressure is too low, the gap of the adjusting ring is too small and should be adjusted appropriately. The discharge pressure of the steam safety valve should be less than or equal to 1.03 times the opening pressure, and the opening and closing pressure difference should not be greater than 10% of the opening pressure. The discharge pressure of the safety valve for air or other gases should be less than or equal to 1.10 times the opening pressure, and the opening and closing pressure difference should not be greater than 15% of the opening pressure.

4. When the safety valve is calibrated and pressure adjusted, there must be a technician in charge of the safety of the boiler and pressure vessel of the user unit. The accuracy of the pressure gauge for the adjustment and calibration device should not be lower than level 1. Safety protection measures.
Pay attention to the adjustment of the discharge pressure and return pressure of spring-type and lever-type safety valves. For the structure with recoil disc and valve seat adjustment ring, the valve seat adjustment ring is used for adjustment. Unscrew the adjusting ring fixing screw, and extend a thin iron rod or the like from the exposed screw hole to move the teeth on the adjusting ring to rotate the adjusting ring left and right. When the adjusting ring is rotated counterclockwise to the left, its position increases, and both the discharge pressure and the return pressure will decrease.