초록 ▼

A valve for a respirator has an elastomeric valve member (18) of generally dished form with an annular channel (25) around its central portion (24). The member (18) is secured at its center by a shouldered conical stem (19) and seals round its periphery (23). The channel (25) allows a sudden collaps

A valve for a respirator has an elastomeric valve member (18) of generally dished form with an annular channel (25) around its central portion (24). The member (18) is secured at its center by a shouldered conical stem (19) and seals round its periphery (23). The channel (25) allows a sudden collapse of resistance to opening force in the direction of the arrow A above a predetermined amount, but a positive biassing action towards closure. The edges of the channel (26,27) are slightly axially displaced from one another. Both inlet and outlet valves of a respirator may be equipped with such a valve member.

대표청구항 ▼

A respirator comprising a facepiece having a gas inlet and a gas outlet, an outlet valve assembly for permitting flow of gas outwardly only at the gas outlet, an inlet valve assembly for permitting flow of gas inwardly only at the gas inlet, at least the outlet valve assembly comprising a valve memb

A respirator comprising a facepiece having a gas inlet and a gas outlet, an outlet valve assembly for permitting flow of gas outwardly only at the gas outlet, an inlet valve assembly for permitting flow of gas inwardly only at the gas inlet, at least the outlet valve assembly comprising a valve member and a valve seat, said valve member comprising a disc of elastomeric material, the disc having a periphery and a central portion, securing means at the central portion of the disc for securing that portion stationary in the valve assembly, part of the periphery of the disc being for sealing contact against the seat of the valve assembly to prohibit gas passage in the non-permitted direction, an annular channel in the disc between the central portion and the periphery thereof, said disc being continuously conical between said channel and said periphery whereby the part on the periphery is positively biassed towards said sealing contact with the seat of the valve assembly but the rate of increase of resistance to gas flow in the permitted direction lessens above a predetermined value of flow, said outlet comprising a speech transmitter with a sound passage therethrough, said sound passage having an inner upstream end and an outer downstream end relative to the permitted direction of flow of gas outwardly from the facepiece, the said outlet valve assembly being in said sound passage with said disc of elastomeric material across the passage, the passage comprising wall means defining a convolute portion of the passage of cross-section increasing progressively in the downstream direction of permitted flow and having at least two substantial reversals of direction, and defining a further portion of the passage which is progressively convergent in the downstream direction of permitted flow, said convolute portion of the passage being downstream of the progressively convergent portion relative to the direction of permitted flow.