21
PRESSURE REGULATOR
The pressure regulator stabilizes the flow of oxygen to the
patient and establishes back pressure on the system. It is pre-
set at 8.5 psi (58.6 kPa) and should not have to be adjusted in
the field.
To test the pressure regulator:
1. Turn the unit “On.”
2. Set the flow meter at 2 lpm.
3. Use a pressure-vacuum gauge (part #PVO2D-60
1) and a fitting
suitable to fit on the oxygen outlet or on a short piece of tub-
ing connected to the outlet.
4. If the pressure-vacuum gauge reads anything other than 8.5 ±
.85 psi (58.6 ± 5.9 kPa) with gauge outlet blocked, adjustment
to the pressure regulator may be required. If so, call Sunrise
Service Department at
11
-800-333-4000 (8
11
4-443-488
11
).
NOTE:
Make sure no leaks exist before adjusting the
pressure regulator.
A malfunction in the pressure regulator will cause either a loss
or fluctuation in the oxygen flow which will be seen on the
flow meter or a decrease in oxygen concentration.
To replace the pressure regulator (Figure 9):
1. Make sure the unit is unplugged from the wall outlet.
2. Remove the front and back cabinets.
3. Remove the tubing clamp and tubing from the pressure regulator.
4. Unscrew the regulator from the accumulator tank.
5. Install a new regulator on the accumulator tank and attach the
tubing and tubing clamp.
6. Replace the front and back cabinets.
PRINTED CIRCUIT BOARD
The printed circuit (PC) board is responsible for monitoring
and controlling the DeVilbiss Oxygen Concentrator.
On non-OSD and early-OSD models, a pressure transducer on
the PC board continuously senses the oxygen pressure in the
accumulator tank.
The PC board has preset alarms for low pressure or low out-
put flow and power failure. Should any of the alarm values be
exceeded, the patient alert system will activate.
NOTE: Non OSD and early OSD models were equipped
with the low pressure alarm. Later OSD models are equipped
with the low flow alarm.
NOTE: If the concentrator has been unused for an
extended period, the unit must run 20 minutes before
the power fail alarm will be enabled.
To remove and replace the PC board
(without integral OSD) (Figure 7A):
1. Make sure the unit is unplugged from the wall outlet.
2. Remove the front and back cabinets and the bib.
3. Disconnect all wires, terminals, and connectors.
4. Remove the
1/16" (1.6 mm) tubing attached to the transducer.
5. Remove the two screws that secure the board to the unit and
remove the PC board.
6. Install the new PC board and secure it using the two screws.
7. Reconnect all electrical wires, terminals, connectors and the
tubing to the transducer
8. Replace the bib and front and back cabinets.
To remove and replace the PC board
(with integral OSD) (Figure 7B):
1. Make sure the unit is unplugged from the wall outlet.
2. Remove the front and back cabinets and the bib.
3. Disconnect all wires , terminals and connectors.
4. Remove the
1/8" (3.2mm) tubing attached to the sensor.
5. Remove the two screws that secure the board to the unit and
remove the PC board.
6. Install the new PC board and secure it using the two screws.
7. Reconnect all electrical wires, terminals, connectors and the
tubing to the sensor.
8. Replace the bib and front and back cabinets.
SIEVE BED CHECK VALVES
A check valve (Figure 9) located between the outlet of each
sieve bed and the accumulator tank allows oxygen to pass
through the sieve beds to the accumulator tank when the bed
pressure is greater than the accumulator tank pressure.These
valves also prevent reverse flow of oxygen from the accumula-
tor to the sieve beds.
Run the accumulator pressure test described in the chapter
Component Testing, Repair, and Replacement. It covers details
of attaching the gauge and a table of acceptable pressure swing
ranges at various altitudes.
A defective check valve will result in a decrease in oxygen
concentration and lower accumulator pressures.
To replace a defective check valve, remove the tubing on
either side of it and install a new valve making sure the outlet
end is toward the accumulator tank.
COMPONENT TESTING, REPAIR, AND REPLACEMENT
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