18
To remove compressor from the mounting plate:
1. Turn compressor upside down so that it is resting on the heads.
2. Remove the four compressor mounting hex nuts and mount-
ing plate.
NOTE: If the compressor must be replaced, the compressor fil-
ter must be removed from the defective compressor. Depending
on the hours of operation, a new compressor filter should be
installed on the compressor if it is replaced or rebuilt.
To remove motor mounts:
1. Unscrew studded motor mounts from compressor feet by
hand.
COOLING FAN
The cooling fan provides a constant air flow to cool the
compressor.The cooling fan is located in the bottom of the
unit below the compressor (Figure
10).
A defective cooling fan may cause the compressor’s internal
thermo-protective device to activate and shut the compressor
off. Should this condition occur, the compressor will require
several minutes for the thermo-protective device to reset.
If the cooling fan is defective, it must be replaced:
1. Make sure the unit is unplugged from the wall outlet.
2. Remove the front and back cabinets.
3. Remove the compressor.
4. Disconnect the cooling fan terminals.
5. Note the position of the fan before removing the four retain-
ing screws that secure the fan to the base of the unit.
6. Remove the defective fan and secure the replacement fan in
position with the four retaining screws.
NOTE: When installing the fan, be sure the air flow directional
arrow on the side of the fan is directed away from the compressor.
7. Reconnect the electrical connector.
8. Reinstall the compressor.
FINAL CHECK VALVE
This check valve is located between the final bacteria filter and
the oxygen outlet fitting.This check valve allows oxygen to
flow only out of the unit.When the unit is turned off and oxy-
gen flow stops, the check valve closes to prevent water from
being drawn into the unit.
A defective final check valve may allow water to be drawn in
from the humidifier bottle when the unit is turned off.This
may occlude the final bacteria filter and/or the flow meter
causing a restriction of flow and making it difficult to adjust
the flow rate.
To replace the final check valve (Figure 8):
1. Make sure the unit is unplugged from the wall outlet.
2. Remove the front and back cabinets and loosen or remove the bib.
3. Remove the hose from the outlet side of the final bacteria filter.
4. Remove the two screws from the back of the oxygen outlet
fitting assembly and remove the assembly.
5. Remove the hose from each end of the final check valve.
6. Attach the hoses to a new check valve. Make sure that the
flat side of the check valve is directed toward the oxygen
outlet fitting.
7. Replace the outlet fitting assembly and connect the hose to
the filter.
8. Replace the bib and front and back cabinets.
FLOW METER
The pressure-compensated flow meter has an accuracy level
of ±5% at full scale (exception: +0%,-5% at 5 lpm).The flow
meter on the DeVilbiss Oxygen Concentrator is designed for
use at 8.5 psi (58.6 kPa) at flow rates up to 5 lpm.
To check for leaks in the flow meter tubing:
1. Check for leaks using a certified leak detection solution such
as Epi-SEAL
®
LEAK-SEEK
®
.
2. Apply leak test solution to all fittings and hose connections
with the unit running.
3. If an air leak is present, the solution will bubble.All leaks should be
repaired before putting the concentrator back in service.
WARNING: Electric Shock Hazard. Use caution when
leak testing near electrical connections.
To replace the flow meter (Figure 8):
1. Make sure the unit is unplugged from the wall outlet.
2. Remove the front and back cabinets.
3. From behind the bib remove the 2 hoses from the flow meter.
4. While squeezing tabs on flow meter brackets, push the flow
meter through the bib.
5. Install new flow meter in bib and reconnect hoses.
FOUR-WAY VALVE
The timed four-way valve alternately distributes pressure sup-
plied by the compressor to the two molecular sieve beds.
While one bed is being pressurized the other bed is being
exhausted through the four-way valve. Exhaust gases passing
through the four-way are exhausted to a black hose connected
to an exhaust muffler.
The dual solenoid four-way valve operates electrically to shift a
spool inside the valve.The valve receives approximately 7.5
VDC (
12-15 VDC on non-OSD and early-OSD models) from
the PC board causing one of these solenoids to activate.When
the left solenoid is activated, the right sieve bed will pressur-
ize.After approx. 9-
10 seconds the approximately 7.5 VDC
(
12-15 VDC on non-OSD and early-OSD models) is removed
causing the left solenoid to deactivate. No voltage is applied to
either solenoid for approximately
1 second.The right solenoid
is then activated causing the left bed to pressurize.
COMPONENT TESTING, REPAIR, AND REPLACEMENT
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