... , the gas runs into the 1st stage cylinder through the gas intake pipe. After the 1st stage ... runs to the 2nd stage cylinderg. Thus, after passing through the 3rd stage cylinder and 4th stage cylinder, ... 20MPa. Finally, the compressed natural gas is discharged through the high pressure de-oil filter where the ... residual oil will be filtered out and fed through the high-pressure hose to fill cars. The ...