Facility for on-site production of medical gas

On-site medical gas production plant (100) comprises e.g. gas purification unit (50) adapted to produce purified gas from supply gas, main gas line (10) supplied with gas by gas purification unit and comprising in series first vessel for storing less pure gas and second vessel for storing purified gas, secondary line (20) fluidically connected to main line, downstream of first vessel for storing less pure gas and comprising third vessel for storing gas, and at least one gas analysis device arranged to determine level of at least one impurity in gas, downstream of second and third vessels. On-site medical gas production plant (100) comprises a gas purification unit (50) adapted to produce a purified gas from a supply gas, a main gas line (10) supplied with a gas by the gas purification unit and comprising in series a first vessel for storing a less pure gas and a second vessel for storing a purified gas, a secondary line (20) fluidically connected to the main line, downstream of the first vessel for storing the less pure gas and comprising a third vessel for storing gas, at least one gas analysis device arranged to determine the level of at least one given impurity in the gas, downstream of the second and third vessels, a first solenoid valve arranged on the main gas line between the first vessel for storing the less pure gas and a second vessel for storing the purified gas, a second solenoid valve arranged on the secondary gas line between the first vessel and the third vessel for storing gas, a third solenoid valve arranged on the main gas line downstream of the second vessel for storing the purified gas, a fourth solenoid valve arranged on the secondary gas line downstream of the third vessel for storing gas, and an operating device (4) which controls the opening or closing of the solenoid valves in response to the impurity level measurement signal received from the gas analysis device. An independent claim is also included for operating the on-site medical gas production plant comprising the main gas line comprising in series first vessel and second vessel, and secondary line fluidically connected to the main line, downstream of the first vessel for storing a less pure gas, and a third vessel for storing gas, the main gas line and the secondary line each supplying at least one gas consumer site, comprising (a) supplying the consumer site with the purified gas having a desired composition coming from the third vessel, (b) supplying the second vessel with