Patent ID: 7870759

Claim:
A method of supplying a pressurized gas, comprising: a) separating a gas mixture in a separation unit ( 3 , 5 ) and producing a first pressurized gas; b) storing a liquid to be pressurized in a storage tank ( 9 ); c) withdrawing at least a portion of the liquid from the storage tank and pressurizing the withdrawn liquid with a pump ( 11 ); d) vaporizing at least part of the pressurized liquid in a vaporizer ( 27 ) and producing a second pressurized gas ( 29 ) having substantially the same composition and purity or a higher purity than the first pressurized gas; e) flowing liquid in an approximately vertical pipe ( 13 ) relative to the separation unit, at least one portion of the length of the pipe lies at a level above the vaporizer; f) sending liquid from the approximately vertical pipe to the vaporizer without passing through the pump ( 11 ) or the storage tank, before and/or during start-up of the pump ( 11 ), said approximately vertical pipe being directly connected to the inlet of the vaporizer; and g) vaporizing the liquid to a third gas and supplying the third gas, the third gas having substantially the same composition and purity or a higher purity than the first pressurized gas ( 31 ).