| 摘要 |
A two-stage breathing apparatus comprises a compressed air supply cylinder (1) provided with a cylinder valve (2) communicating through a highpressure duct (3) with a manifold (4). A first highpressure branch (5) of the manifold (4) communicates with a pressure indicator warning unit (6) and a second high pressure branch (7), comprising a high pressure flexible hose, connects the manifold (4) via a nonreturn valve (8) with a high pressure quick release connector (10). The manifold (4) contains a pressure reducer (11) which feeds a demand valve (12) provided on a breathing mask (14) via a further flexible hose (13). The non-return valve (8) permits flow in the direction from the high-pressure quick release connector (10) to the supply cylinder (1), but prevents flow in the direction from the supply tank (1) to the high-pressure quick release connector (10). Consequently, the supply tank (1) can be replenished rapidly via the quick release connector (10), but if the connector (10) fails or the high pressure flexible hose bursts, the non-return valve prevents the loss of compressed air to the atmosphere.
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