Abstract: A plurality of pressure vessels are filled with acetylene gas by an apparatus which has a gas delivery conduit with a plurality of delivery connections. A drive mechanism moves pressure vessel supports from a loading station to locations where each pressure vessel is located at and conducted to a respective gas delivery connection. The gas delivery conduit is stationary, but its mountings permit horizontal movement to avoid damage to the apparatus if the supports are accidentally moved when the pressure vessels are attached to the delivery connections. When the gas delivery conduit is displaced more than a certain amount from its normal stationary position, power to the drive mechanism is automatically cut off. The supports for the pressure vessels are oriented to house the pressure vessels at an inclination which maintains them steady. The disclosed drive mechanism has two pneumatic cylinders for driving the supports along a slide of a fixed structure.