Return pressure refers to the safety valve to discharge the state, the medium pressure drops to a certain value, the disc and the valve seat contact, that is, the opening height becomes zero, the static pressure at the valve inlet.
The return pressure is too low or too high is not good, too low will cause the loss of medium and energy, too high will not reach the emissions, resulting in valve frequency jump, the principle is to reach the emissions under the condition of the return pressure as high as possible, reduce the loss of medium and energy,
Adjustment method: the back seat pressure is adjusted by the regulating ring, the principle of regulation is the principle of clearance, the smaller the clearance, the greater the resistance when ejection, the greater the force to hold the spool down, the more difficult to return to the seat.
On the contrary, the greater the clearance, the easier the spool to fall back, the higher the return pressure.
For the safety valve with only the lower regulating ring, the regulating ring is up, the return seat pressure is down, the regulating ring is down, the return seat pressure is up;
For the safety valve with the upper and lower regulating ring, the distance of the upper and lower regulating ring decreases, the return pressure decreases, the distance of the upper and lower regulating ring increases, the return pressure increases.
