Abstract: A CVD device A is provided which is equipped with a gas introduction part A3 having an inert gas supply part G1 for supplying a diluting inert gas and a cleaning gas supply path G2 for supplying a cleaning gas, each connected therewith, and equipped with an exhaust gas discharge part A4 for releasing an exhaust gas; an exhaust gas circulation part D1 for circulating an exhaust gas from the CVD device, a cooling part D4 for cooling down and liquefying the cleaning gas in the exhaust gas, and a recovery part 4 for recovering the cleaning gas liquefied in said cooling part D4; the diluting inert gas is composed of a gas having a boiling point lower than that of the cleaning gas; a supply part 6 for supplying a cooling inert gas having the same composition as the diluting inert gas in a liquid state, an inert gas circulation part D3 which is cooled down by heat of evaporation of the cooling inert gas, and an inert gas discharge part 7 for discharging the cooling inert gas evaporated in the inert gas circulation p

Abstract: Provided is a gas recovery unit which is more efficient in its recovery and less expensive to run. The gas recovery unit comprises a CVD device, an exhaust gas recovery part and an exhaust gas purification part. The exhaust gas recovery part is constructed so as to have an inert gas reservoir part capable of accommodating liquid nitrogen, to have an exhaust gas supply part for supplying an exhaust gas to said inert gas reservoir part so that it can be brought in gasliquid contact with the liquid nitrogen, and to have a recovered and liquefied gas discharge part for discharging the recovered and liquefied gas which has been liquefied in the inert gas reservoir part.

Abstract: A gas filling facility and method which maintains the purity of a gas to be filled. A connection of a gas supply pipe and a gas filling pipe attached on gas containers is performed in a first clean room while the storage of the gas filling pipe occurs in a second clean room. When the gas filling pipe is stored, ultra-high purity nitrogen gas is caused to flow through the inside thereof, so that the inside of the gas filling pipe remains under an extremely clean state.

Abstract: A method of treating an inner surface of a high-pressure gas vessel is disclosed. In the method, abrasive containing rust preventive is charged into the vessel made preferably of manganese steel or chrome-molybdenum steel and a wet-grinding step is carried out to obtain a maximum inner surface roughness of the vessel of 3 .mu.m or less. Thereafter, the inner surface is rinsed with an acidic rinsing solution.