The swelling mechanism of nitrile rubber in liquefied dimethyl ether organic solution can be understood as follows: when the valve of the cylinder is opened, the liquefied dimethyl ether in the bottle contacts with the nitrile rubber sealing ring in the valve, and the nitrile rubber will swell; When the cylinder valve is closed, the interior of the valve is gradually "dry", the swelling property of nitrile rubber is gradually declining, and the volume of rubber will shrink. With the increase of the number of valve opening and the increase of dimethyl ether content in liquefied petroleum gas, After many times of "swelling-shrinkage" stress cycle, the rubber stress decreases, the aging speeds up, and finally the rubber elastic failure reduces the sealing performance, which leads to the leakage of the valve.