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SCBA working principle

SCBA working principle is that compressed air of a cylinder passes through a cylinder valve to enter a pressure reduce valve. At the same time the air pressure in the cylinder is indicated by a pressure gauge. When the high pressure air is reduced to 0.8±0.15 MPa medium pressure, it flows through a medium pressure hose to a lung governed demand valve that is connected to a face piece. The lung governed demand valve can provide over 30L/min airflow according to user’s demand. When a user causes a negative pressure by inhaling a rubber membrane of the lung governed demand valve shrinks back and the airflow enters the full face mask. When a user exhales, pressure of the face mask increases, demand valve automatically stop air supply, and one-way exhalation valve automatically opens to discharge the air exhaled from the face mask, which will be repeated. When the compressed air in the cylinder is about to run out, the alarm signals that the user shall be evacuated as soon as possible.