A. Dewar bottle vacuum damage, with internal leakage

Phenomenon:No insulation, rapid and sharp increase in pressure after filling, large surface frost, rupture disc damage exhaust, the risk of mechanical explosion of the bottle.
Solution: Scatter the surrounding personnel, open the inlet and outlet valves to drain the liquid, open the venting valve to exhaust, first carry out the inner gas replacement to avoid personal accidents. Repair processing: leak detection, repair.
Nuclear mass spectrometry leak detector: If the internal leakage, break open the outer bile, find the leakage point welding, replace the palladium oxide, molecular sieve, insulation paper and other internal materials. Then weld the outer bile to recover and re-vacuum to ≤6.4×10-3Pa.
If external leakage, break open the outer gallbladder, replace the wrapping material, replace palladium oxide, molecular sieve, weld the outer gallbladder to recover, and vacuum to ≤6.4×10-3Pa from the beginning. after repair, need to make evaporation rate test.

 
B.The vacuum failure of Dewar bottle
Phenomenon: The outer gall has frost phenomenon, the hand temperature is lower than the ambient temperature, placed in 1 day on the active exhaust.
Solution: Exhaust the remaining gas as soon as possible and send to repair. Need to make internal and external leakage, helium mass spectrometry leak detection, if there is internal or external leakage, according to the above methods to repair, if there is no internal or external leakage, need to heat vacuum treatment from the beginning. If it is used for a long time, the internal material should be replaced.

C.The safety accessories are damaged
(1) Rupture disc damage, check the factors, whether there is a large area of frost phenomenon, if so, according to the internal leakage, external leakage, check the disposal. If there is no local dew or frost, it is recommended to replace the rupture disc first, observe the rate of pressurization after filling the liquid, such as faster pressurization, the vacuum problem should be considered. If the pressurization is normal, it belongs to the rupture disc aging caused by.
(2) The pressure gauge is damaged, replace the new one.
(3) Safety valve leakage, replace the new one.
(4) The level meter is damaged, replace the new one.
(5) The valve does not close tightly, air leakage, replace the valve spool.