REBREATHER SYSTEM (cont)

TM 10-8415-208-12 When the bottle valve (1) is opened, oxygen is continuously supplied to the breathing chamber (2). Additional oxygen is automatically added by the demand/free flow valve (3) to compensate for the user's work rate or face piece (4) leakage. When the user inhales, breathing air flows from the breathing chamber (2) through the coolant canister (5) to the inhalation hose (6) and the face piece (4). When the user exhales, the exhaled breath passes through the exhalation hose (7), through the carbon dioxide absorber (8) where carbon dioxide is removed then into the breathing chamber (2), where fresh oxygen is added. If the user's inhalation causes the breathing diaphragm (9) to bottom, the demand/free flow valve (3) automatically supplies the additional oxygen required. In addition, if the user's exhalation causes the breathing diaphragm (9) to fully expand, any excess gas will be vented out of the breathing chamber (2) through the relief valve (10). The breathing chamber (2) is maintained at a slight positive pressure with respect to ambient pressure by a compression spring (11) which exerts a force on the breathing diaphragm (9). The bypass valve button (12) is for emergency use only. The valve bypasses the constant flow restrictor and it can be manually operated if the user is not getting enough breathing air. WARNING Limited oxygen supply in the rebreather system. Leave the area immediately when the alarm whistle sounds. An audible alarm indicates the oxygen pressure has dropped to 25% or below and about 45 minutes of oxygen is available. Failure to leave the area and decontaminate immediately could result in personnel death due to suffocation. An audible alarm (13) sounds for approximately 20 to 45 seconds when the oxygen bottle (14) pressure drops to 25% (600 PSIG) of the operating pressure. The alarm (13) is designed with an alarm tone stem which, when covered, causes a distinct change in sound. This lets the user identify if it is his oxygen supply that is running low and must leave the area immediately. When the oxygen bottle (14) pressure drops to 25% (600 PSIG) of operating pressure, the user has about 45 minutes to decontaminate and remove the encapsulating protective suit. 1-17/(1-18 blank)