SELF-CONTAINED BREATHING APPARATUS

摘要

Self-contained breathing apparatus has a container for receiving exhaled gas, means for removing carbon dioxide from the exhaled gas, sensor means for detecting the oxygen content of the exhaled gas and means for injecting oxygen into the exhaled gas to reinstate the oxygen content so as to lie within a desired range for rebreathing, in which the signals from the oxygen sensor means are delivered to two independent signal processing circuits which are interconnected in a primary and secondary relationship with the primary signal processing circuit acting in use to control the operation of a solenoid valve for injection of oxygen into the exhaled gas and the secondary signal processing circuit acting in use to display information concerning the sensor output signals to provide confirmation of the satisfactory operation of the master signal processing circuit.