A gas releasing and/or regulating mechanism is equipped with a body (1) with a passage, a gas intake (2) and outlet (3), the intake and outlet being connected to the passage; elements to block (5, 6, 7, 8) the passage; mobile elements (9) which associated to the body (1) of the mechanism, define a low pressure chamber (11) below the blocking elements (5, 6, 7, 8), the mobile elements (9) operating the blocking elements (5, 6, 7, 8) depending on the pressure within the low pressure chamber (11). The blocking elements (5, 6, 7, 8) are made of a first shutter (5, 6) and a second shutter (7, 8) below the first in the passage; and the first and second shutters (5, 6, 7, 8) are mechanically connected so that the first shutter (5, 6) closes before the second one (7, 8).