A spring-loaded diaphragm in the breathing chamber maintains the positive pressure in the system. If the user's inhalation fully depletes the breathing chamber, the demand, free flow valve automatically supplies the additional oxygen required. If the user's exhalation causes the diaphragm to fully expand, excess gas is vented out of the relief valve.
A loud, high-pitched, pressure activated whistle alarm sounds when approximately 20-25% service life remains. A manual bypass is provided to override the supply system in an emergency.
In the BioPak 240, a "blue ice" coolant canister is added to the inhalation side of the breathing circuit to cool the breathing gas on the way to the mask.
Biomarine Inc., 456 Creamery Way, Exton, PA 19341. Tel: 610-524-8800; Fax: 610-524-8807.