10 Prima 451 – User Manual
Description
3.6
Flowmeters
and C
on
t
r
o
l
s
3.6.1
F
l
o
w
m
e
t
e
r
s
The flowmeters, mounted behind the perspex cover on the
left hand side of the machine, are length-indexed to prevent
inadvertent, incorrect installation.
All floats
indicate
flow rate in line with
t
h
e upper surface
(X), as shown a
bo
v
e
.
3.6.2 Flow C
on
t
r
o
l
s
Each flow control valve is positioned directly underneath the
flow tube assembly to which it corresponds, and the control
knob (1) is colour-coded for the gas which it controls.
The oxygen flow control knob is made physically
distinguishable from the other flow controls for identification
by touch, in accordance with ISO standards.
When fitted, the air flowmeter is always installed in the inner
position on the flowmeter assembly
This position is blanked out if air is not specified for the
machine.
Flow control of each gas is achieved by a needle valve
comprising a polished stainless steel needle mounted
concentrically in a common manifold block.
The flow control knob is turned counter-clockwise to increase
the gas flow.
C
A
U
TIO
N
Needle valves are designed to seal with light torque and
may be damaged if tightened excessively.
DO NOT USE EXCESSIVE FORCE
NOTE
1. The gas delivery switch (2), positioned on the front panel
controls the supply of oxygen and must be in the ON position
for normal operation of the machine.
2. The switch also controls the operation of the AV-S
ventilator. (see section 3.9.3).
3.6.3 Dual Cascade Flow
T
ub
e
s
The flow of gas through dual cascade system flow tubes
always flows through the low-flow tube first. The high-flow
tube should not show any flow until more than 1 L/min is set.
At flows above 1 L/min, the high-flow tube reading indicates
the rate of flow for that gas.
X X
1
2
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