DeVilbiss 525 Series Service Manual download pdf (Page 17)

LT-2023

MOLECULAR SIEVE BEDS

The two molecular sieve beds alternately remove the nitrogen from the

air passing through them and provide the patient with a constant supply of

oxygen.

The efﬁciency of the molecular sieve material will be impaired if it

becomes contaminated by moisture. Contamination causes the molecular

sieve material to lose its nitrogen adsorbing properties resulting in a

decrease in oxygen concentration. The unit should run for a minimum of

20 minutes before turning "Off" to prevent problems associated with

moisture contamination in the system.

To test the sieve beds:

1. Remove the 1/16" plugged piece of tubing from the top of each sieve

bed.

2. Connect the pressure-vacuum gauges to the sieve bed test points

(Figure 9) in order to observe unit cycling and bed pressures. Refer

to the section on Normal Operating Sequence.

3. If it is determined that the valve did not shift, refer to the section on

Rotary Valve testing. However, if the unit is cycling properly allow

unit to run while observing the sieve bed pressures.

4. After 20 minutes of operation, check the oxygen concentration

levels. Low oxygen concentration and high pressures indicate

contaminated sieve beds.

NOTE– If the molecular sieve material is found to be no longer

effective,rstlocatethesourceofthemalfunctionorcause

(suchasleaks)forcontaminationandtakecorrectiveaction.

To replace the molecular sieve beds (Figs. 5 & 6):

1. Make sure any contamination problem has been corrected before

replacing.

2. Make sure the unit is unplugged from the wall outlet.

3. Cut the plastic cable ties that secure the sieve beds to the internal

structure of the unit.

4. Remove the tubing from the ﬁttings at the top of each sieve bed.

5. Remove the hose clamps and hose from the bottom of the sieve

beds.

6. Install new sieve beds in reverse order using new plastic cable ties.

Position the new beds so that the bed serial number label is at the

top of the unit.

NOTE– Make sure that the sealing caps remain on the new sieve beds

untiljustpriortoconnectinghosesandtubing.

7. Leak test all connections with a certiﬁed leak detection solution such

as Snoop® or equivalent (must not contain ethylene glycol). Apply

leak test solution to all ﬁttings and hose connections with unit

running. If an air leak is present, the solution will bubble. All leaks

should be repaired before putting the unit back in service.

CAUTION– Do not apply leak test solution to any part of the rotary

valve or the main PC Board assembly.

POWER CORD

To replace the power cord - 115 volt units only

(Fig. 11 & 14):

1. Make sure the unit is unplugged from the wall outlet.

2. Remove the back cabinet.

3. Disconnect the power cord connector.

NOTE–Looseningorremovingthecompressormountingplatemay

make it easier to service the power cord.

4. Note wire colors and socket locations before removing wires.

5. Using a pair of duckbill pliers, squeeze the power cord strain relief

and pull it out of the base of the unit.

6. Insert a new power cord through the hole in the base of the unit and

secure with strain relief.

7. Insert sockets into connector housing and then reconnect the power

cord connector.

8. Replace back cabinet and secure with the six screws.

POWER SWITCH

To replace the power switch (Figure 10):

1. Make sure the unit is unplugged from the wall outlet.

2. Remove the front and back cabinets and loosen the bib.

3. Note the position of the wires and switch before removing the wires

from the switch terminals.

4. While squeezing the locking tabs on the sides of the switch, push the

switch out of the front of the bib.

5. Install the new switch in the correct orientation making sure that it

locks into position.

6. Reconnect the wires to the switch terminals.

PRESSURE REGULATOR

The pressure regulator stabilizes the ﬂow of oxygen to the patient and

establishes back pressure on the system. It is preset 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-601) and a ﬁtting

suitable to ﬁt on the oxygen outlet or on a short piece of tubing

connected to the outlet.

4. If the pressure-vacuum gauge reads anything other than 8.5 ± .5 psi

(58.6 ± 5.9 kPa) with gauge outlet blocked, adjustment to the

pressure regulator may be required. If so, call DeVilbiss Service

Department at 1-800-338-1988 (814-443-4881).

NOTE–Makesurenoleaksexistbeforeadjustingthepressure

regulatorbyusingacertiedleakdetectionsolutionsuchas

Snoop®orequivalent(mustnotcontainethyleneglycol).

CAUTION– Do not apply leak test solution to any part of the rotary

valve or the main PC Board assembly.

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.

COMPONENT TESTING, REPAIR, AND REPLACEMENT

Brown Wire (or 2 Black Wires)

2 Black Wires (or 1 Brown Wire)

*Red Wire

* Either red wire can be connected to

either left hand terminal of the switch

Switch Detail

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 43 44

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DeVilbiss 525 Series Service Manual Page 17

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