FIELD: rescue service.
SUBSTANCE: respirator containing a fixing assembly and a mask base comprising an exhalation valve which in its turn consists of a valve seat that comprises an orifice and a non-circular sealing surface surrounding the orifice and a non-circular elastic fold attached to the valve seat at the centre of the elastic fold masses and containing a variable stiffness design.
EFFECT: exhalation valve with this construction may advantageously provide an optimum pressure drop and overall valve performance for those applications in which the valve space may be limited.
18 cl, 6 dwg,5 tbl
