A Self Contained Re-breathing apparatus with a single bank of oxygen
sensors for signaling oxygen contact back to a display and oxygen valve
control, where the signal is set via two identical and independent sets of
signal control circuitry which are interconnected in a primary and
secondary relationship. The primary circuitry controlling the valve and
the secondary circuitry sending a signal to a display, wherein the two
identical and independent sets of circuitry can perform each role and
serve to confirm the satisfactory operation of a master signal processing
circuit.
