US3739774A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Respirators
Assignee: ML Aviation Ltd
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Filing: 1971-05-10
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Granted: 1973-06-19
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Expires: 1991-05-10
Abstract
Abstract A respirator for use in noxious atmospheres comprises a hood which completely covers the head of the wearer and the edge of which extends around his neck or shoulders and a mechanical blower is fitted to the inlet connection so as to provide more air than required for respiration to provide a positive internal pressure. The respirator may also serve as an oxygen mask for use at high altitudes by airmen and preferably includes a separate oro-nasal mask in which case the inlet has two branches, one passing to the mask by way of a non-return valve and the other passing to the interior of the hood also through a non-return valve. When oxygen is being supplied a valve operates to prevent the flow of air from the blower to the mask.
Inventors
- 👤 J Gregory
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:51
CPC Classifications
A; A62; A62B; A62B7/00; A62B18/00; A62B18/04
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
166 words
A respirator comprising a hood which is dimensioned to completely cover the head of the wearer and has a terminal lower edge dimensioned to encircle the body of the wearer beneath his head to define a narrow passageway between said edge and said body, an oro-nasal mask within said hood, an inlet for admitting air to said hood, said inlet having two branches, one leading into said mask through a first non-return valve, and the other leading into the interior of said hood outside said mask through a second non-return valve, a mechanical blower connected to supply air to said inlet, whereby a portion thereof passes through said second non-return valve into said hood outside said mask and thence outwardly through the passage bwtewwn the edge of the hood and the body of the wearer, a connector for connecting said mask to a supply of oxygen, and means for preventing the flow of air from said blower to said mask while said oxygen is being supplied.
Claim 2
Dependent Claim
166 words
A respirator comprising a hood which is dimensioned to completely cover the head of the wearer and has a terminal lower edge dimensioned to encircle the body of the wearer beneath his head to define a narrow passageway between said edge and said body, an oro-nasal mask within said hood, an inlet for admitting air to said hood, said inlet having two branches, one leading into said mask through a first non-return valve, and the other leading into the interior of said hood outside said mask through a second non-return valve, a mechanical blower connected to supply air to said inlet, whereby a portion thereof passes through said second non-return valve into said hood outside said mask and thence outwardly through the passage bwtewwn the edge of the hood and the body of the wearer, a connector for connecting said mask to a supply of oxygen, and means for preventing the flow of air from said blower to said mask while said oxygen is being supplied.
Claim 3
Dependent Claim
114 words
A respirator as claimed in claim 1 in which said first non-return valve comprises a valve-member and a seat and said flow-preventing means comprises means urging said valve member against said seat with a force small enough to permit air to flow through said first non-return valve from said blower to said mask when no oxygen is being supplied, a main spring for urging said valve member more strongly toward said seat, and means for bringing said main spring into action under the control of the oxygen pressure when said oxygen is being supplied so as to hold said valve member more firmly on said seat against the pressure of air form said blower.
Claim 4
Dependent Claim
105 words
A respirator as claimed in claim 1 in which said first non-return valve is a plate valve comprising first and second plates, a seat, a light spring positioned between said first and second plates to press said first plate against said seat, a cylinder containing a piston responsive to the oxygen pressure when oxygen is being supplied to move said second plate closer to said first plate, thus compressing said light spring, and a main spring between said plates which is shorter than said light spring and urged against said first plate by said second plate when said piston is subjected to said oxygen pressure.
Claim 5
Dependent Claim
27 words
A respirator as claimed in claim 3 comprising a spring-operated latch for holding said piston in the position to which it is moved by said oxygen pressure.
Claim 6
Dependent Claim
55 words
A respirator as claimed in claim 4 in which said latch is a spring-operated plunger passing through a sealed opening in said cylinder and being formed with a portion of reduced diameter which when brought into register with said opening, permits a throttled flow of oxygen from the interior of said cylinder to said mask.
Claim 7
Dependent Claim
22 words
A respirator as claimed in claim 1 comprising an air eXhaust duct leading from said mask to the exterior of said hood.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |