Datex-Ohmeda Aespire 7900, User'S Reference Manual

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Aespire 7900
6-4
1009-0633-000
Gas supplies
Gas goes into the system through a pipeline or cylinder connection. All
connections have indexed fittings, filters, and check (one-way) valves. Gauges
show the cylinder and pipeline pressures.
A regulator decreases the cylinder pressures to the appropriate system
pressure. A pressure relief valve helps protect the system from high pressures.
To help prevent problems with the gas supplies:
• Install yoke plugs on all empty cylinder connections.
• When a pipeline supply is connected, keep the cylinder valve closed.
w
WARNING Do not leave gas cylinder valves open if the pipeline supply is in
use. Cylinder supplies could be depleted, leaving an insufficient
reserve supply in case of pipeline failure.
O
2
flow
Pipeline or regulated cylinder pressure supplies O
2
directly to the ventilator
(O
2
Ventilator).
The flush valve supplies high flows of O
2
to the fresh gas outlet when you push
the flush button. The flush switch uses pressure changes to monitor the
position of the flush valve. A message on the ventilator tells you when Flush is
ON.
When the system switch is ON, O
2
flows to the rest of the system and there is a
minimum flow through the O
2
flowmeter.
A secondary regulator supplies a constant O
2
pressure to the flow control
valve.
An electrical switch monitors the O
2
supply pressure. If the pressure is too low,
an alarm appears on the ventilator.
Air and N
2
O
A balance regulator controls the flow of N
2
O to the flow control valve. Oxygen
pressure at a control port adjusts the output of the regulator. This stops flow
during an O
2
supply failure and ensures that the hypoxic gas pressures
decrease with the O
2
supply pressure. Changes in O
2
pressure do not affect
Air.
A chain linkage on the N
2
O and O
2
flow controls helps keep the O
2
concentration higher than approximately 21% at the fresh gas outlet.
Pipeline or regulated cylinder pressure directly supply Air to the ventilator (Air
Ventilators). When the system switch is ON, air flows to the rest of the system.
Because there is no balance regulator, air flow continues at the set rate during
an O
2
supply failure.