8 Prima 451 – User Manual
Description
Secondary
Pressure Re
gu
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a
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A second stage regulator reduces the pressure supplied to
each flowmeter control (see section 4).
The fitment of a secondary regulator for oxygen and nitrous
oxide enhances the performance of the mechanical AHD
system. Secondary regulation of the air supply aids the
stabilisation of the output at the flowmeter.
3.3 Gas Supply Safety De
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3.3.1 Gas Supply Cut-off De
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A gas cut-off device, triggered by low oxygen supply pressure,
cuts the supply of nitrous oxide.
The supply of nitrous oxide is reinstated only when the oxygen
supply pressure rises above the cut-off value.
3.3.2 Oxygen Supply Failure
W
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n
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ng
W
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WARNING:
Refer to WARNING 20
(section
1).
A whistle gives an audible warning when there is a reduction
of oxygen supply pressure.
The warning whistle is operated solely by the remaining
oxygen in the machine system, and the warning is prolonged
by an oxygen reservoir built into the gas circuit, allowing a
minimum warning whistle of 7 seconds duration.
The whistle will start to sound when the pressure falls to 200
± 21 kPa (29 ± 3 psig), and will continue to sound until the
pressure falls to approximately 70 kPa (10 psig).
Oxygen consumption of the whistle is approximately 2 L/min
when sounding and nil at other times.
3.3.3 Fresh Gas Pressure Relief
V
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e
A pressure relief valve is fitted to prevent fresh gas being
delivered to the breathing system at pressures exceeding 90
cmH
2
O.
3.3.4 Oxygen Supply Visual
I
nd
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WARNING:
Refer to Warning 20
(section
1).
The indicator (1) is mounted on the front of the machine and
is operated from the oxygen supply and shows GREEN when
the supply is at working pressure, and RED if the pressure
falls.
3.3.5
Mechanical Anti-hypoxic Device (
A
HD)
The AHD ensures a fresh gas mixture with a minimum of 30%
(±3%) oxygen throughout the delivery range.
See
section
3.4 for a full
d
e
sc
r
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t
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on
3.3.6 Low Pressure Gas
T
ub
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ng
Diameter-indexed tubing is used for the low pressure gas
system - see section 4.
1
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