Abstract: A valve assembly (20) for a respirator comprises a valve body (25) having a valve outlet portion and a valve inlet portion which together define a valve cavity (30) for a valve mechanism (24) permitting gas flow from the valve inlet portion to the valve portion member, an air purge means comprising a purge inlet, connectable to an air pressure supply means, an air purge outlet (27) and an air deflection means (28) in which the deflection means is spatially arranged relative to the valve mechanism and purge outlet so that, in use, air exiting the purge outlet and incident the air deflection means provides a curtain of air over the valve mechanism.