When exhaling, the gas flows through the channel (item 1) via the exhalation valve (item 2) and lifts the sealing disc (item 3) after which the gas can escape into the surroundings through the slits in the cover (item 4).

The valve mechanism serves as a safety valve for the regulator unit through the sealing cone automatically opening if the secondary pressure exceeds about 20 bar (2 MPa). This can occur, for example, if the regulator unit becomes uptight. The balancing spring (item 5) can then no longer resist the pressure on the central part of the balancing diaphragm (item 6).

Whereupon the back-pressure piston (item 7) is pressed inwards and affected ensuring the valve mechanism is lifted and pulls the sealing cone from the valve seat whereby gas is released until the pressure drops to about 10 bar (1 MPa).