Dräger Narkomed 2B, Service Manual, Page: 66 / 308

REPLACEMENT PROCEDURES (continued) NM2B
4.11 Oxygen Ratio Controller (machines with E-Z Plumb piping)
The Oxygen Ratio Controller (ORC) is part of the N
2
O flowmeter sub-assembly
and is located within the flowmeter housing. The ORC is accessible by
removing the rear flowmeter housing cover. Figure 4-11 shows a typical ORC
location and mounting arrangement, with a detail of the O-rings and filter.
The following procedure applies to both ORC designs: P/N 4111800, and Low
Flow design P/N 4113229.
4.11.1 Disconnect all pipeline hoses and set the System Power switch to ON.
4.11.2 Close all cylinder valves except the O
2
valve.
4.11.3 Set the oxygen flow to 5 liters per min.
4.11.4 Open the other gas flow control valves to drain pressure from the
system.
4.11.5 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.
4.11.6 Set the System, Power switch to STANDBY.
4.11.7 Remove the press-on clamp securing the flexible O
2
line to the ORC,
and carefully disconnect the tubing from the hose barb.
4.11.8 Remove the three screws holding the ORC to the flowmeter sub-
assembly, and carefully remove the ORC from the flowmeter housing.
4.11.9 For low flow ORC (P/N 4113229) replacement, install the 6 in. length
of flexible tubing with a blue N
2
O label on the replacement ORC (see
detail view in illustration) Secure each connection with a press-on
hose clamp.
Position the replacement ORC at the back of the N
2
O flowmeter sub-
assembly; be sure that its O-rings and filter are in place, and install
its three mounting screws.
4.11.10 Connect the flexible O
2
line to the ORC and secure it with the press-
on hose clamp.
4.11.11 Open the O
2
and N
2
O cylinder valves.
Rev. F
4-34
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