| abstract |
In a compressed gas supply system, particularly for supplying helium under pressure to inflate balloons, as in balloon vending machines, two tanks containing gas under pressure are connected to a supply line through respective pressure regulating valves set to feed gas under relatively low pressures from the respective tanks to the supply line, and the regulating valve associated with one of the tanks is set to feed at a pressure slightly higher than that at which the other regulating valve is set to feed so that gas is initially supplied from the tank whose regulating valve is set at the slightly higher pressure and feeding of gas from the other tank commences automatically only when the pressure of gas in the first tank has been reduced substantially to the pressure setting of the regulating valve for that other tank. |