Abstract: A valve assembly operable to fill a container with pressurized gas from a source thereof and to vent the cylinder and associated passage means in the valve assembly to atmosphere, the cylinder having a valve with a valve member spring biased to a closed position. The valve assembly has a valve housing within a main chamber, a supply port connectable to a source of pressurized gas, a fill port connectable to a cylinder to be filled, and a vent port communicating with the atmosphere, the supply port, fill port and vent port communicating with the main chamber. A valve body is mounted in the main chamber for movement therein and having a first passage operable in a first position of the valve body to connect the fill port to the vent port, a second passage operable in a second position of the valve body to connect the supply port to the fill port, and a third passage operable in a third position of the valve body to connect the fill port to the vent port.