
NM2B
REPLACEMENT PROCEDURES (continued)
4.6
Flow Control Valves
The flow control valves have replaceable elements that are removable from the
front of the gas instrumentation panel as shown in Figure 4-6. Each flow
control knob has a clockwise positive stop arrangement that prevents damage
to the valve seat. Whenever a valve cartridge is replaced, the "off stop" must
be set as outlined in the following procedure.
4.6.1
Disconnect all pipeline hoses and set the System Power switch to ON.
4.6.2
Close all cylinder valves except the O
2
valve.
4.6.3
Set the oxygen flow to 5 liters per min.
4.6.4
Open the other gas flow control valves to drain pressure from the
system.
4.6.5
Close the O
2
cylinder valve and the O
2
flow control valve. Press the
O
2
Flush valve to drain oxygen pressure from the system.
4.6.6
Set the System Power switch to
STANDBY
.
4.6.7
Remove the O
2
flow control knob, and the knob on the valve to be
replaced.
4.6.8
Remove the two screws holding the knob guard in place, and remove
the knob guard. (For earlier machines with the bar-type knob guard,
the screws holding the guard assembly are accessible through the
back of the flowmeter assembly.)
4.6.9
Remove the stop pin nut.
4.6.10
Remove the flow control valve by holding it at the wrench flats and
turning it counter-clockwise.
4.6.11
Install the replacement flow control valve in the valve housing.
CAUTION: Before tightening the cartridge, rotate the valve shaft
several turns counter-clockwise to prevent bottoming the
valve element into the seat when the cartridge is
tightened.
4.6.12
Replace the stop pin nut.
4.6.13
Replace the knob guard and secure it with the two mounting screws.
(Replace the bar-type knob guard on earlier machines.)
Rev. A
4-19
Содержание Narkomed 2B
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