In numerous industrial fields, the current trend is to require sources of gas at increasingly high pressures. For industries consuming large quantities of gas, this gas is generally brought in the gaseous phase to the high pressure by a compressor, the gas being produced in situ by a unit for producing the gas, generally by cryogenic separation. For smaller gas consumptions, this gas is generally stored in liquid form at low pressure, vaporized and pressurized.
Even with high gas pressures in the meaning of the present invention, that is to say greater than 10.times.10.sup.5 Pa and possibly greater than 100.times.10.sup.5 Pa, these technologies do not pose major problems in continuous operation. It is, however, necessary to provide, in case of malfunction of the main installation, a backup installation capable of taking over, for at least a limited period of time, the production of the gas. At the pressure levels in question, backup installations do, however, pose problems, especially as regards their capacity to provide the gas immediately at the required pressure. In this respect, the setting-up of a nominal regime with a pump or a compressor is a serious handicap.