Analysis on Possibility of Failure of Dewar Safety Valve

When you find that the Dewar safety valve fails, do you know the reasons? Do you know how to deal with it?

1. The function of the safety valve is that when the pressure in the Dewar bottle exceeds the safety pressure, that is, when the pressure in the bottle exceeds the set pressure of the safety valve, the safety valve will jump and release the pressure to the safety pressure and then automatically lock and close. This is used to protect the liner from overpressure damage.

2. After overpressure, the safety valve automatically opens. After the pressure is released to a safe pressure, the safety valve appears to be out of gas. (The cause is that the exhaust time is too long, the sealing surface of the safety valve freezes, or dust sticks to the sealing surface, causing seal failure) Solution: pour boiling water on the safety valve, and use a wooden stick or nylon rod to gently tap the safety valve .

3. Without overpressure exhaust, the safety valve will trip frequently for a long time, resulting in fatigue damage to the spring. Pouring with hot water has no effect. (The solution is to replace it directly after emptying).