The gas machine components can also be logically conceptualized by the amount of pneumatic pressure they are exposed to:
The High-pressure circuit consists of those parts which receive gas at cylinder pressure
hanger yoke (including filter and unidirectional valve)
yoke block
cylinder pressure gauge
cylinder pressure regulators
The Intermediate pressure circuit receives gases at low, relatively constant pressures (37-55 psi, which is pipeline pressure, or the pressure downstream of a cylinder regulator)
pipeline inlets and pressure gauges
ventilator power inlet
Oxygen pressure-failure device (fail-safe) and alarm
flowmeter valves
oxygen and nitrous oxide second-stage regulators
oxygen flush valve
The Low-pressure circuit includes components distal to the flowmeter needle
flowmeter tubes
check valves (if present)
common gas outlet