Abstract: The housing (5, 6) of the regulator contains a medium-pressure chamber (10) to which gas is supplied from the cylinder when a self-closing cylinder valve (2) is open and which communicates with the regulator outlet (14) through a further valve (b 13), and a low-pressure chamber (23) in open communication with the outlet. The medium-pressure chamber (10) has a diaphragm wall (15) with a spindle (16) for controlling the cylinder valve (2). The low-pressure chamber (23) has a diaphragm wall (22) for controlling the further valve (13) through a connecting rod (20) carried by the diaphragm wall and coacting at its upper end with a manual selector (21) and at its lower end with the valve opener spindle (16). By means of the selector the connecting rod may be locked in a raised position in which the cylinder valve (2) is closed.