An improved oxygen breathing apparatus (OBA), the A-4 model developed by the Naval Ship Engineering Center, is being distributed to U.S. Navy ships after undergoing a successful operational evaluation. The OBA is a self-contained, closed-circuit device by which oxygen, generated by chemicals in a canister, can be breathed by the wearer, independent of the surrounding atmosphere, for about 60 minutes. The improvements over the older A-3 model, in use since 1953, are extensive. First of all, the A-4 OBA offers wearers better visibility, replacing the A-3 model's two-lens facepiece with a larger single visor-type facepiece. The A-4 also provides better maneuverability. Its quick-adjusting shoulder harness and improved head harness provide a tighter fit and allow greater ease in donning and activating and, as a result, a faster response time. Other improvements over the older A-3 model include an automatic relief valve that eliminates the need for manual venting and a sturdy, quick-acting canister bail assembly that withstands prolonged use and further decreases response time.

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  • Accession Number: 00194737
  • Record Type: Publication
  • Source Agency: Navy Technology Transfer Sheet
  • Files: TRIS
  • Created Date: Jun 30 1979 12:00AM