A valving arrangement for a mobile gas supply system includes a primary inlet port, a primary outlet port, a regulator, a secondary inlet port, and a secondary outlet port. The primary inlet port is adapted to be connected to a gas cylinder. The primary outlet port is in fluid communication with the primary inlet port and is adapted to be connected to one or more accessories for delivering gas from the gas cylinder. The regulator is disposed between the primary inlet port and the primary outlet port for reducing the pressure of the gas delivered by the gas cylinder to the primary inlet port. The secondary inlet port is in fluid communication with the primary outlet port. The secondary outlet port is in fluid communication with the primary outlet port and the secondary inlet port. The secondary inlet and secondary outlet ports are adapted for connecting the valving arrangement to one or more additional gas cylinders.