a. The Delivery Circuit.
Components. The delivery circuit consists of the following items and
(a) The oxygen and nitrous oxide gas cylinders.
(b) The cylinder regulator assemblies.
The cylinder adapters (if using large cylinders).
(d) The pressure sensor shut-off valve.
(e) The flow control valves and flow meters.
The oxygen flush valve.
(g) The anesthetic vaporizer.
The flow. Refer to figures 1-1 and 1-2.
(a) Oxygen and nitrous oxide cylinders provide the gas supply for the
anesthesia apparatus. The output from both cylinder gas supplies leave their respective
cylinders at high pressures. They must be regulated to a lower pressure before
entering the supply hoses leading to the control head. Regulators within the regulator
assemblies reduce the cylinder gas supply pressures to about 40 pounds per square
inch as measured on a gauge (psig).
(b) Both oxygen and nitrous oxide flow out of their respective regulator
assemblies through the supply hoses into the control head. Oxygen takes three flow
paths after it enters the control head; nitrous oxide takes only one path.
(c) Metabolic oxygen flows to the metabolic oxygen flow control valve
which, if open, admits the oxygen flow to the metabolic oxygen flow meter. After
measurement, the oxygen flows into the common mixing passage in the flow meter top
(d) Metabolic oxygen also flows through the pressure sensor valve in
the nitrous oxide flow path. The pressure sensor valve closes off nitrous oxide if there
is an oxygen supply failure or depletion. If the pressure sensor valve and the nitrous
oxide flow control valve are open, nitrous oxide flows to the nitrous oxide flow meter.
Measured nitrous oxide then flows into the common mixing passage. There it mixes
with the metabolic oxygen flow. The oxygen-nitrous oxide mixture flows directly into the
breathing circuit. It does not enter the vaporizer at any time.