Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
170 words
Breathing apparatus comprising a face mask (1) for covering the nose and mouth of the wearer and having inlet means (2) and outlet means (3) for gas, non-return outlet valve means (4) being adapted for maintaining a positive differential pressure within said face mask, pump and filter means (6, 9) having an outlet (11) connected to the face mask inlet means for supplying filtered ambient air to said face mask, controllable valve means (13) having an inlet (14) for connection to a supply of pressurised breathable gas, and an outlet (16) connected to said face mask inlet means (2), and pressure sensitive control means (19, 20) for controlling said controllable valve means and adapted to cause opening of said controllable valve means (13) in the event that the pressure in said face mask falls below a preset minimum relative to ambient pressure, such that under normal operating conditions said controllable valve means (13) remains closed, filtered ambient air being supplied to said face mask by said pump and filter means.
Claim 2
Dependent Claim
170 words
Breathing apparatus comprising a face mask (1) for covering the nose and mouth of the wearer and having inlet means (2) and outlet means (3) for gas, non-return outlet valve means (4) being adapted for maintaining a positive differential pressure within said face mask, pump and filter means (6, 9) having an outlet (11) connected to the face mask inlet means for supplying filtered ambient air to said face mask, controllable valve means (13) having an inlet (14) for connection to a supply of pressurised breathable gas, and an outlet (16) connected to said face mask inlet means (2), and pressure sensitive control means (19, 20) for controlling said controllable valve means and adapted to cause opening of said controllable valve means (13) in the event that the pressure in said face mask falls below a preset minimum relative to ambient pressure, such that under normal operating conditions said controllable valve means (13) remains closed, filtered ambient air being supplied to said face mask by said pump and filter means.
Claim 3
Dependent Claim
39 words
Apparatus as claimed in claim 1, wherein said control means (19, 20) are adapted to cause closing of said controllable valve means (13) when the pressure within said face mask rises above a level above said preset minimum level.
Claim 4
Dependent Claim
49 words
Apparatus as claimed in either claim 1 or claim 2, wherein said pressure sensitive control means (19, 20) includes a diaphragm (19) arranged so that one face is subject to ambient pressure and the other face is subject to the pressure in the outlet of said controllable valve means.
Claim 5
Dependent Claim
52 words
Apparatus as claimed in any one of the preceding claims, wherein said controllable valve means (13) comprises a valve member (18) which is movable between open and closed positions and means are provided for causing movement of said valve member depending on the condition of said pressure sensitive control means (19, 20).
Claim 6
Dependent Claim
72 words
Apparatus as claimed in any one of the preceding claims, wherein said pump and filter means comprises air moving means (6) mounted in a pump housing (30) providing an inlet (7) and said outlet (11), a battery operated motor (29) connected for driving said air moving means (6) which is also mounted within said pump housing (30) and filter means (9) provided for filtering air entering said inlet of said pump housing.
Claim 7
Dependent Claim
42 words
Apparatus as claimed in claim 5, wherein said filter means comprises filter material in a filter housing having an inlet (10) and an outlet (8) connected to said pump housing inlet (7), said filter housing inlet (10) being open to the atmosphere.
Claim 8
Dependent Claim
58 words
Apparatus as claimed in either claim 5 or claim 6, wherein said gas moving means comprises a fan (6) and non-return valve means (12) are provided in the path of flow of air from said pump (6) to said face mask for preventing reverse flow of breathable gas through said pump when said controllable valve (13) is open.
Claim 9
Dependent Claim
53 words
Apparatus as claimed in any one of the preceding claims, wherein said face mask inlet means (2) comprises a single inlet opening to which both the outlet (16) of said controllable valve means (13) and the outlet (11) of said pump and filter means (6, 9) are connected by connect ing means (21).
Claim 10
Dependent Claim
98 words
Apparatus as claimed in claim 8, wherein said means (21) connecting said outlet of said pump and filter means (6, 9) and said outlet of said controllable valve means (13) to said face mask inlet means (2) comprises a generally T-shaped connector having an upright and a cross-bar open at their ends, the open end (22) of the upright being connected to said face mask inlet (2) and the open ends (24, 25) of the cross bar being connected to the outlets of said controllable valve means (13) and of said pump and filter means respectively (6, 9).
Claim 11
Dependent Claim
33 words
Apparatus as claimed in claim 9, wherein non-return valves (12, 17) are mounted in said connector adjacent the open ends (24, 25) of said cross bar for preventing reverse flow of gas therethrough.
Claim 12
Dependent Claim
58 words
Apparatus as claimed in any one of the preceding claims, wherein said face mask inlet means (2) comprises two inlet openings (29, 26), said outlet of said pump and filter means (6, 9) being connected to one said inlet opening (29) and said outlet of said controllable valve means (13) being connected to said other inlet opening (26).