pressure relief valve for gas, particularly for fuel vapours.

摘要

A gas-pressure relief valve unit, particularly for fuel vapours, comprising a body (3) defining a chamber (10) which communicates with first and second environments upstream and downstream of the unit (1) respectively, through first and second apertures (12, 14). The body is provided with valve means (15) including a valve seat (18) interposed between the apertures (12, 14) and an obturator (20) urged by a resilient thrust element (24) and movable between a position of engagement with the seat (18) and a position spaced from the seat (18). The obturator (20) can move away from the valve seat (18), overcoming the action of the resilient element (24), when a predetermined threshold value of the pressure differential between the environments is reached. When the obturator (20) is engaged with the seat (18) and the pressure differential between the environments is less than the predetermined threshold value, the valve means (15) define a narrow passage (28) which allows a small, continuous flow of gas between the first and second environments. IMAGE