Replace O Or N - GE Aespire 7100 Technical Reference Manual

9.7.9 Replace O
2
or N
2
0 needle
valves (on
machlnes wlth
N
2
0)
9 Repair Procedures
For machines without N
2
0 , referto Section 9.7.10 for replacing the O
2
needle valve.
1. Bleed all gas pressure from the machine (Section 9.1).
2. Ensure 由 at all cylinder and pipeline gauges read zero before proceeding.
3. Remove the front flowmeter panel shield (Section 9.7.1).
4. Set the O
2
and N
2
0 needle valves to their minimum position.
5. Loosen the set screws on the N
2
0 knob , then remove the knob.
6. Loosen the set screws on the N
2
0 sprocket and the O
2
knob.
7. To remove , grasp the O
2
knobjsprocket , N
2
0 sprocket , and chain as an assembly.
Remove as an assembly.
8. Remove the spacer from the N
2
0 needle valve spindle.
9. Loosen the set screws on the needle valve stop collar for the needle valve that is
being replaced.
10. Remove the stop collar.
1 1. To remove the needle valve from the flowmeter block , turn the needle valve
counterclockwise with a 16-mm wrench.
12. To install the new needle valve , turn it clockwise and tighten it with the wrench.
Note: Be sure the o-ring is properly located on the tip ofthe needle valve .
.&.
WARNING
Th
e O
2
and N
2
0 needle valves are not the same. Patient injury can result ifthe
wrong needle valve is installed in the flowmeter block. You can identify the N
2
0
needle valve by a groove located just below the top brass hex.
Ml110140 08/07
O
2
needle valve has no groove
N
2
0
needle valve has a grooye
,
13. Install the stop collar on the new needle valve. Do not tighten the set screws.
14. Perform the needle valve calibration (Section 5.3).
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