Chapter

Equipment*Packet:*Oxygen'Concentrator*UMDNS*#:'12815''Date*of*Creation:'October'21,'2015'Creator:'Complied'by'Cassandra'Stanco'for*Engineering'World'Health'(EWH)***Equipment*Packet*Contents:*This'packet'contains'information'about'the'operation,'maintenance,'and'repair'of'oxygen'concentrators.''Part*I:*External*From*the*Packet:** 1. An*Introduction*to*Oxygen*Concentrators:*PowerPoint'*Part*II:*Included*in*this*Packet:** 1. Operation*and*Use:*a. Brief'Introduction'to'Oxygen'Concentrators'(p.'3)'b. Introduction'to'Oxygen'Concentrators'(p.'4M7)'c. Operation'and'Use'of'Oxygen'Concentrators'(p.'8M9)'2. Diagrams*and*Schematics:*a. Figure'1:'Diagram'of'a'Basic'Oxygen'Concentrator'(p.11)'b. Figure'2:'Block'Diagram'of'an'Oxygen'Concentrator'(p.'12)'3. Preventative*Maintenance*and*Safety:*a. Oxygen'Concentrator'Preventative'Maintenance'(p.'14)'b. Oxygen'Concentrator'Calibration'and'Measurement'(p.'15M20)'4. Troubleshooting*and*Repair:**a. Oxygen'Concentrator'Troubleshooting'Flowchart'(p.22M25)'b. Oxygen'Concentrator'Troubleshooting'Table'(p.'26M27)'5. Resources*for*More*Information*a. Resources'for'More'Information'(p.'29)'b. Bibliography'(p.'30)'* '*** **




**1.*Operation*and*Use*of*Oxygen*Concentrators****Featured*in*this*Section:****Malkin,'Robert.'“Oxygen'Concentrators.”'Medical%Instrumentation%in%the%Developing%World.'Engineering'World'Health,'2006.'' **Strengthening'Specialised'Clinical'Services'in'the'Pacific.'User%Care%of%Medical%Equipment:%A%first%line%maintenance%guide%for%end%users.'(2015).''* *Wikipedia.'“Oxygen'Concentrator.”'Wikipedia,'p.'1^5.'Retrieved'from:'https://en.wikipedia.org/wiki/Oxygen_concentrator'* ** *




User Care of Medical Equipment – First line maintenance for end users


42


Chapter 4.12 Oxygen Concentrators


Function
An oxygen concentrator draws in room air, separates the oxygen from the other gases in the air and


delivers the concentrated oxygen to the patient. When set at a rate of two litres per minute, the gas that is
delivered by the concentrator is more than 90% oxygen. It is used for situations where bottled gas supply is
impractical or expensive, and can be used by patients in the hospital or the home.


How it works
Atmospheric air consists of approximately 80% nitrogen and 20% oxygen. An oxygen concentrator uses


air as a source of oxygen by separating these two components. It utilizes the property of zeolite granules to
selectively absorb nitrogen from compressed air. Atmospheric air is gathered, filtered and raised to a pressure of
20 pounds per square inch (psi) by a compressor. The compressed air is then introduced into one of the canisters
containing zeolite granules where nitrogen is selectively absorbed leaving the residual oxygen available for
patient use. After about 20 seconds the supply of compressed air is automatically diverted to the second canister
where the process is repeated enabling the output of oxygen to continue uninterrupted. While the pressure in the
second canister is at 20 psi the pressure in the first canister is reduced to zero. This allows nitrogen to be released
from the zeolite and returned into the atmosphere. The zeolite is then regenerated and ready for the next cycle.
By alternating the pressure between the two canisters, a constant supply of oxygen is produced and the zeolite is
continually being regenerated. Individual units have an output of up to five litres per minute with an oxygen
concentration of up to 95%.





Humidifier bottle


Flow meter




Oxygen concentrator 1


Oxygen concentrator


A home oxygen concentrator in situ in an
Emphysema patient's house. The model shown is


the DeVILBISS LT 4000.


An Invacare Perfecto 2 oxygen concentrator


An oxygen concentrator is a device used to provide oxygen therapy to
a patient at substantially higher concentrations than available in


ambient air. They are used as a safer, less expensive, and more


convenient alternative to tanks of compressed oxygen. Common


models retail at around US$800. Leasing arrangements may be


available through various medical-supply companies and/or insurance


agencies.


Oxygen concentrators are also used to provide an economical source of


oxygen in industrial processes.


How they work
The simplest oxygen concentrator is capable of continuous delivery of


oxygen and has internal functions based around two cylinders, filled


with a zeolite material, which selectively adsorbs the nitrogen in the


air. In each cycle, air flows through one cylinder at a pressure of


around 20 lbf/in² (138 kPa, or 1.36 atmospheres) where the nitrogen


molecules are captured by the zeolite, while the other cylinder is


vented off to ambient atmospheric pressure allowing the captured


nitrogen to dissipate.


Typical units have cycles of around 20 seconds, and allow for a


continuous supply of oxygen at a flow rate of up to approximately five


liters per minute (LPM) at concentrations anywhere from 50 to 95 %.


This process is called pressure swing adsorption (PSA).[1] Since 1999,


concentrators providing up to 10 LPM have been available for high


flow patients, in sizes not much larger or heavier than 5 LPM


concentrators.


Portable oxygen concentrators
Since 2000, a number of manufacturers have introduced portable


oxygen concentrators. Typically, these produce less than one liter per


minute (LPM) of oxygen and use some version of pulse flow or


demand flow to deliver oxygen only when the patient is inhaling.


However, there are few portable oxygen concentrators that produce 3


LPM of continuous-flow oxygen. Also providing pulse flow available


to either provide higher flows or reduce power consumption. These portable concentrators typically plug into a wall


outlet like the larger, heavier stationary concentrators. [2]


Portable oxygen concentrators usually can also be plugged into a vehicle DC adapter, and most have the ability to


run from battery power as well, either for ambulatory use or for use away from power or for airplane travel. The


FAA has approved portable oxygen concentrators for use on commercial airlines, although it is necessary to check in


advance whether a particular brand or model is permitted on a particular airline.




Oxygen concentrator 2


Historically, demand or pulse flow concentrators have not been used for nocturnal use—sleeping. If the nasal
cannula moves such that the concentrator is not able to detect when the patient is inhaling, it is unable to deliver the


pulse while the patient is inhaling.


Military uses
Oxygen concentrators are currently being used by the US military in the conflicts in Iraq and Afghanistan as part of


the equipment complement of forward surgical teams.


Safety
In both clinical and emergency-care situations, oxygen concentrators have the advantage of not being as dangerous


as oxygen cylinders, which can, if ruptured or leaking, greatly increase the combustion rate of a fire. As such,


oxygen concentrators are particularly advantageous in military or disaster situations, where oxygen tanks may be


dangerous or infeasible.


Oxygen concentrators are considered sufficiently non-volatile to be leased to individual patients as a prescription


item for use in their homes. Typically they are used as an adjunct to CPAP treatment of severe sleep apnea. There


also are other medical uses for oxygen concentrators, including emphysema and other respiratory diseases.


Used, refurbished, and temperamental units are worthless to the medical community since an individual's health


frequently relies on the constant extended operation of the unit. However, such units are valuable to metal and


glasswork hobbyists. Oxygen is one of the more expensive bottled gases. Medical oxygen concentrators or dedicated


industrial (non-medical) oxygen concentrators can be made to operate a small oxy-acetylene torch quite easily, if


only at lower pressures.[3]


Industrial oxygen concentrators
Industrial processes may use much higher pressures and flows than medical units. To meet that need, another


process, called vacuum swing adsorption (VSA), has been developed by Air Products. It uses a single low pressure


blower and a valve which reverses the flow through the blower so that the regeneration phase occurs under a


vacuum. Generators using this process are being marketed to the aquaculture industry.[4] Industrial oxygen


concentrators are often available in a much wider range of capacities than medical concentrators.


Industrial units are sometimes referred to as oxygen generators within the oxygen and ozone industries to
disambiguate from medical oxygen concentrators. The distinction is used in an attempt to clarify that industrial
oxygen concentrators that are not FDA-approved medical devices are not suitable for use as bedside medical


concentrators. However, applying the oxygen generator nomenclature can lead to confusion. The term, oxygen


generator, is a misnomer in that oxygen is not generated as it is with a chemical oxygen generator, but rather is
concentrated from the air. The use of the oxygen generator terminology can also be a problem for shipping logistics


in the wake of the ValuJet Flight 592 crash. Non-medical oxygen concentrators can be used as a feed gas to a


medical oxygen system, like a hospital oxygen system, although FDA (or other region-specific regulatory, like CE)


approval is required, additional filtration is generally required, and there may be other regulatory requirements as


well.




Oxygen concentrator 3


See also
• Portable oxygen concentrator
• The section on Storage and Sources of Oxygen in the Oxygen therapy article.


Notes
[1] (http:/ / www. airoxnigen. com/ psa_oxygen. htm)
[2] "Sequal" (http:/ / www. sequal. com/ medical. php). Sequal. . Retrieved 2010-04-30.
[3] (http:/ / pyronamix. com/ page6. html)
[4] http:/ / www. airproducts. com/ Products/ Equipment/ PrismGasGenerationSystems/ Prism_oxygen/ adsorption_process-description. htm


• 5. Airsep Website (http:/ / www. airsep. com/ )




Article Sources and Contributors 4


Article Sources and Contributors
Oxygen concentrator  Source: http://en.wikipedia.org/w/index.php?oldid=359235268  Contributors: Afaprof01, Airplaneman, Andrewjlockley, BanyanTree, Bobblewik, BrokenSphere, Bryan
Derksen, Captain-n00dle, DabMachine, Donfbreed, Fisharmor, Fluidcreativity, GiollaUidir, HiEv, Intermedical, John, KayDee, Kerowyn, Ksooder, Lg king, Metrax, Mini-Geek, Mscott0,


NCurse, No1anyoneknows, Oldlaptop321, Pearle, Poodleboy, PurpleHz, R. S. Shaw, Ranchoschmitz, Rjwilmsi, Robert A West, Russkeller, Sbmehta, Smilerehab, Tenorcnj, Tmonzenet,


Wavelength, Wdfarmer, Weregerbil, WmRowan, 31 anonymous edits


Image Sources, Licenses and Contributors
File:Home oxygen concentrator.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Home_oxygen_concentrator.jpg  License: Creative Commons Attribution-Sharealike 2.0
 Contributors: Original uploader was GiollaUidir at en.wikipedia
File:Invacare Perfecto 2 Oxygen Concentrator.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:Invacare_Perfecto_2_Oxygen_Concentrator.JPG  License: Attribution
 Contributors: User:BrokenSphere


License
Creative Commons Attribution-Share Alike 3.0 Unported
http:/ / creativecommons. org/ licenses/ by-sa/ 3. 0/




Equipment found in the OR, ICU and ER


Page 20


2.3 Oxygen Concentrators


2.3.1 Clinical Use and Principles of Operation

Oxygen is a widely prescribed medication in both the hospital and home setting. Hypoxia, or an
inadequate amount of oxygen, is the main physiological state requiring this medical technology
and is present in a number of life-threatening conditions. These include chronic obstructive
pulmonary disease (COPD), which refers to the restriction, inflammation, or infection of
bronchioles or alveoli whereby oxygen supply or transfer to the blood is limited. Cardiovascular
insufficiency also causes hypoxia when an irregular rhythm, decreased flow, or inefficient
transport prevents adequate oxygen delivery to peripheral tissues.

In addition to these medical conditions, a reliable source of oxygen is essential wherever
anesthetics are administered, both to supplement the inspired gas mixture and also for
resuscitation, though other machines such as ventilators may be selectively used.

Oxygen has traditionally been supplied in cylinders in the developing world. However, cylinders
are both bulky and expensive. In isolated areas transportation of cylinders is difficult and may be
unreliable. For these reasons, The World Health Organization recommends oxygen concentrators
as a better long-term investment for smaller, remote hospitals in the developing world.


Engineering Details


Ambient air contains 78% N, 21% O2 and 1% trace gases. An oxygen concentrator works by
separating and removing the nitrogen from the ambient air, leaving nearly pure (95%) oxygen.
At high flow rates the oxygen concentration may drop.

Most machines now operate using pressure swing adsorption (PSA). Ambient air is compressed
and passed through a synthetic aluminum silicate (zeolite). Zeolite acts as a molecular sieve by
binding to nitrogen, but only at high pressures. The zeolite is designed with a porous
configuration to maximize surface area.

The high pressure, concentrated, oxygen is stored in a tank. A pressure regulator is used to step
down the pressure to the desired range.

After the zeolite is saturated with nitrogen, the valve leading to the oxygen tank is closed and the
pressure is decreased in the zeolite tank. As the pressure drops the zeolite releases nitrogen
which is vented into the air. A small quantity of enriched oxygen is then passed backwards
through the zeolite canister to completely purge the zeolite of nitrogen. Since the patient
probably needs a continuous supply of oxygen, a typical concentrator will have two zeolite
canisters. One is concentrating oxygen while the other is being purged.

An oxygen concentrator is easy to operate with only a power switch and a flow meter. An alarm
sounds if the pressure in the compression chamber falls below 20 psi. Some models include a
built-in device called an OCSI (oxygen concentration status indicator) that measures the oxygen
concentration just before the outlet. An alarm would sound if the concentration is low in these
devices. Some machines automatically shut down if the concentration of oxygen falls below
70%.




Medical Instruments in the Developing World Malkin


Page 21


2.3.2 Common Problems


Concentrators do malfunction occasionally, and their repair can require considerable expertise;
worn parts on the compressor and valves may need replacement. Assuming that all other parts
function optimally, the machine is only limited by the life of the zeolite crystals, which is expected
to be at least 20,000 hours.


The primary complaints are low oxygen concentrations and decreased gas flows. Since this
machine is so widely used and has few options on the interface, user error is unlikely. A clogged
filter may be the cause. The filter is located between the air source and the zeolite containers.
Some models may have multiple filters. A dirty filter can lead to a decreased oxygen
concentration and/or a decreased flow rate.

If the flow to the patient is insufficient, the tubing and connectors should be checked for leaks.
Remember that part of the oxygen-providing pathway from the zeolite canisters can be inside of
the machine.

If the motor or compressor is not functioning properly, air in the zeolite canisters will not be
pressurized enough to remove an adequate amount of nitrogen from the air. It is necessary in
this case to check any seals/gaskets associated with these systems. Inside the chambers, 20psi is
the standard pressure.

The valves at the inlet and outlet of the zeolite canisters must be tight and timed correctly.
During pressurization, the inlet valve should be opened and the outlet valve should be closed.
During filtering, which normally takes 8 to 20 seconds, both valves should be closed as nitrogen
binds to the zeolite. During release of oxygen-concentrated air to the patient, only the outlet
valve should be opened. Remember that in the regeneration stage a small amount of oxygen is
released back into the canister to expel leftover nitrogen. Most models have valves that are
coordinated between chambers. However, check the timing of valve opening and closing.
Canisters will be in different stages of the pressure swing cycle so that while one canister is
filtering, the other is regenerating.


2.3.3 Suggested Minimal Testing


It is important that this machine achieve oxygen concentrations near 90% or above and provide
gas flows in the manufacturer’s range, keeping in mind that for high flow rates (around 5
liters/minute) oxygen concentration will be lower. In addition, it is not safe to trust flow meters
and oxygen concentration indicators on the machine when releasing an oxygen concentrator to
the floor. These variables need to be checked using a separate oxygen analyzer and flow meter,
respectively. It is not typically difficult to determine the flow rate in the developing world, as
there is an abundance of flow meters. However, measuring oxygen concentration can be
challenging. If you are unable to locate an oxygen concentration meter, discuss the problem
with the physician before releasing the device to the floor without an oxygen concentration test.
The measurement must be performed 10 minutes after switching the concentrator on to give the
machine time to build up the concentration of oxygen.





2.*Diagrams*and*Schematics*of*Oxygen*Concentrators****Featured*in*this*Section:******Developing'World'Healthcare'Technology'Laboratory.'“Oxygen'Monitors.”'From'the'Publication:'“Biomedical'Technicians'Training'Program,'Session'3'v2,'Special'Topics:'Cardiac'Equipment.”'Engineering%World%Health,'March'1,'2011,'p.'115^159.''''Skeet,'Muriel'and'David'Fear.'“Oxygen'Concentrators.”'Care%and%Safe%Use%of%Medical%Equipment.'VSO'Books,'1995.''** *








3.*Preventative*Maintenance*and*Safety*of*Oxygen*Concentrators****Featured*in*this*Section:*****Cooper,'Justin'and'Alex'Dahinten'for'EWH.'“Oxygen'Concentrator'Preventative'Maintenance.”'From'the'publication:'Medical%Equipment%Troubleshooting%Flowchart%Handbook.'Durham,'NC:'Engineering'World'Health,'2013.'**DHT'Laboratory.''“Oxygen'Concentrator'Measurement.”'From'the'publication:'Biomedical'Technician'Assistant'(BTA)'Skills,'Duke'University:'DHT'Lab,'2011.'*




EQUIPMENT))Oxygen)Concentrator)Preventative)Maintenance)
Preventive(Maintenance((Always'run'machine'for'a'few'hours'after'maintenance'before'patient'use'1. Clean(humidifier(and(tubes(a. Wash(in(warm(soapy(water,(rinse(thoroughly,(and(replace(2. Change(distilled(water(3. Remove(and(clean(the(foam(air(intake(filter((a. Wash(with(soap(and(water(b. Ensure(filter(is(dry(before'replacing(but(do'not(use(heat(to(dry(4. Check(Alarm(system(battery(a. An(audible(alarm(should(sound(when(the(machine(is(turned(on(b. Replace(9V(battery(when(necessary(5. Check(if(Zeolite(Canisters(have(expired((25,000(hours).(The(granules(become(grey(when(they(are(no(longer(effective.((6. Felt(preNfilter(should(be(changed(once(a(month((if(available)(7. Replace(patient(bacterial(filter(annually((if(available)(((




Knowledge Domain: Mechanical
Unit: Calibration
Skill: Oxygen Concentration Measurement

Tools and Parts Required:


1. Wide basin or pan
2. Water
3. Adhesive substance eg. putty, chewing gum or gluestick
4. Glass Bottle 90-220ml,eg.food jar, beaker (must be glass).
5. Aluminum foil Enough to cover mouth of bottle
6. Small candles ~75% bottle height, much narrower than mouth of bottle
7. Lighter or matches
8. Electrical tape
9. Wooden stick <4cm, narrower than mouth of bottle
10. Volume measurer eg. graduated cylinder, syringe, or measuring cups
11. Dishwashing soap
12. Spreading utensil eg. butter knife
13. Marker
14. Pencil
15. Paper
16. Safety goggles (optional)
17. Heat-resistant gloves (optional)
18. O2 Concentrator or O2 Cylinder with tubing



Introduction
This test measures the concentration of oxygen in a sample of air. This test can be used
to measure the output oxygen concentration of an oxygen concentrator. Oxygen
concentrators must be tested to insure that they are functioning properly.

Identification and Diagnosis
An oxygen concentrator device provides concentrated oxygen to the patient. It is
important to know that the device can deliver concentrated oxygen. Use this method to
measure the concentration of oxygen provided by the oxygen concentrator. The
measurement is based on a change in the volume of gas that occurs during a
combustion reaction. Record the measurements on a piece of paper. You may want an
assistant for help.




Procedure
Preparation
1) Find a glass bottle that holds 90 to 220 ml of liquid. You can use a lab beaker, or


any food jar, such as pickle, jam, peanut butter jars.
x The bottle must be glass. Plastic will melt and change shape with the candle


flame. The oxygen measurement will not be accurate with a plastic bottle.
x The bottle must be between 90-220 ml. This volume range has been tested for


accuracy. If your bottle is larger or smaller, the oxygen measurement will not be
accurate.



2) Find a candle of appropriate height and thickness.
x The candle height must be 75% of the bottle height. If the candle is too short,


extend the candle by taping a wooden stick to the candle. If the candle is too
long, cut off the top end with a heated butter knife or scissors.


x The candle should fit into the mouth of the bottle. If the candle is too thick, use
the butter knife to scrape the candle in a rotating motion until it is the correct size.



3) Using a knife or other spreading utensil, apply dishwashing soap to the candle. The


soap protects the wax from burning too quickly. If you do not soap the candle, it will
flame too quickly. Do not soap the wick of the candle.



4) Insert the candle into the adhesive putty (or gum or


gluestick). The adhesive putty should hold the candle
upright. Insure that the bottle can be lowered over the
candle. Stick the adhesive putty and the attached
candle to the bottom of the basin. Insure that the
apparatus is secure.


  


5) Fill the basin with 3-4 cm of water.


 


 
Step 3: Use a knife to apply 


diswashing soap to the candle. 


 
Step 2: The candle height must 
be 75% of the bottle height.   


 


Step 4: Insert the candle 
into the adhesive putty.  


Candle


Adhesive 
putty 


Wooden 
Stick


Adhesive 
Tape 




6) Fill the bottle with water. Measure the bottle volume by pouring this water into a
volume measuring device (graduated cylinder, syringe, or measuring cups). Record
the bottle volume.






Fill the bottle with gas to be measured
(Find a partner to assist you with the remaining steps. Follow the appropriate steps for
filling the bottle with oxygen, room air, or a mixture of both.)

Measuring an oxygen concentrator/cylinder:
7) Fill the bottle completely with water. Cover the bottle mouth with the palm of your


hand and turn the bottle upside-down. Keep your hand over the bottle mouth to
prevent leakage. Place your hand and the bottle into the water-filled basin. When
the mouth of the bottle is underwater, remove your hand. Insure that water does
not leak out of the bottle. The bottle should now be full of water and upside down.



8) Bring the oxygen concentrator close to the basin. Insert the oxygen concentrator


tube under the bottle mouth. Turn on the concentrator. The oxygen will displace the
water in the bottle. You should see gas bubbles entering the bottle. Fill the entire
bottle with gas. The bottle mouth must remain underwater.


9) After the entire bottle is full of gas, remove the tube. Immediately slide the aluminum
foil under the bottle mouth. Fasten the aluminum foil around the bottle mouth. Insure
that the bottle remains underwater. Do not allow the oxygen to leak out.


10) Light the candle.


 
Step 6: Fill the bottle with water. 


Measure the bottle volume. 


 
 


Step 5: Fill the basin with  
3‐4 cm of water. 




 


Measuring room air:
11) Light the candle.
12) Skip straight to step 16. You will not need the aluminum foil.

Measuring a mix of room air and oxygen:
13) Follow the steps 6, except fill the bottle only partially with water.
14) Follow steps 7 – 9.

Burn away the oxygen
15) Carefully lift the bottle from the water along with the aluminum foil. Let any water on


the aluminum foil drip out. Insure that the aluminum foil maintains a tight seal
around the mouth of the bottle. Do not allow the gas inside the bottle to leak out.



16) Place the bottle above the flame. The bottle should be upside down and the


aluminum foil-covered mouth of the bottle should be above the candle flame. Do
not allow the gas inside the bottle to leak out.



**Note: Be careful in the next step. If you have a high concentration of oxygen, the
candle flame will suddenly flare. The flame should be very big. There may be a hissing
sound. Do not be frightened. The bottle will not explode.

17) In one, quick motion, remove the aluminum foil from the mouth of the bottle and


lower the bottle over the lighted candle. Hold the bottle down perpendicular to the
basin with the bottle mouth underwater. As the flame burns oxygen, water will enter
the bottle from the water basin. Insure that the mouth of the bottle remains
underwater.



18) Wait for the flame to die out and let the water level rise in the bottle.
x If bubbles pop around the bottle mouth, repeat the procedure. Insure that the


bottle remains perpendicular to the basin.


 


 
Step: 7Invert the filled 


bottle into the basin. Insure 
that water does not leak! 


Step 9: Slide the aluminum foil 
under the bottle.  


Step 8: Fill the bottle with gas 
you want to measure.  




 
Step 21: Fill the bottle up to the mark. Measure 


this water volume. 


x If the water reaches the flame before the flame dies, repeat the procedure. Make
sure to re-soap the candle.


19) After the water stops entering the bottle, mark the water level on the bottle.



20) Remove the bottle from the basin. Fill the bottle with water to release smoke.


Discard the water.

21) Fill the bottle with water up to the


mark. Measure the volume of the
water in mL. Record this measured
volume.



22) Repeat the procedure with a new


candle. Record the second
measured volume.



23) Average the measured volumes


obtained. Record this value as the
average volume.



24) Refer to the chart on the following


page to determine the oxygen
concentration.


 
Step 19: Mark the water level on 


the bottle. 


Step 17: In one quick motion, remove the 
aluminum foil and lower the bottle over 


the lighted candle. 




Exercise
Measure the O2 concentration with an O2 cylinder or concentrator, room air, and a mix of
the two. Follow steps 1-6 by yourself. Pair up with a partner for the remaining steps.
After the first person is finished, the other partner will complete the exercise. Your
instructor must verify your work before you continue.


Record your values in the following table:



O2 Cylinder /


O2 Concentrator
Room Air


Unknown
Concentration


Bottle Volume


Measured Volume #1


Measured Volume #2


Average Volume


Oxygen Concentration



To measure oxygen concentration:
1. Locate Average measured volume on the x-axis
2. Locate Bottle volume on the y-axis.
3. Locate where these two values intersect on the graph. The line closest to the


intersection represents the oxygen concentration (as % O2 in air).




Preventative Maintenance and Calibration
Insure that there are no cracks or leaks in oxygen concentrators. Check the oxygen
level in the oxygen concentrators approximately every six months. Always calibrate
every medical device before returning it to use.




4.*Troubleshooting*and*Repair*of*Oxygen*Concentrators****Featured*in*this*Section:***Cooper,'Justin'and'Alex'Dahinten'for'EWH.'“Oxygen'Concentrator'Troubleshooting'Flowchart.”'From'the'publication:'Medical%Equipment%Troubleshooting%Flowchart%Handbook.'Durham,'NC:'Engineering'World'Health,'2013.'** Strengthening'Specialised'Clinical'Services'in'the'Pacific.'User%Care%of%Medical%Equipment:%A%first%line%maintenance%guide%for%end%users.'(2015).'* *




EQUIPMENT))Oxygen)Concentrator)Repair)and)Troubleshooting)




!Description+#! Text&Box! Explanation!
1! Begin!O2!Concentrator!Testing! Start!the!diagnostic!process!for!a!work!order!on!O2!Concentrator.!
2! Does!the!machine!power!up?! With!unit!plugged!in,!and!power!switch!turned!on,!the!display!should!light!up!and!compressor!should!run,!making!noise.!
3! Is!the!inlet!filter!in!place?! Some!models!require!the!compressor!inlet!filter!to!be!in!place!in!order!for!machine!to!start.!For!all!other!models,!proceed!to!step!5.!4! Install!inlet!filter! If!available,!install!the!foam!inlet!filter.!
5! Troubleshoot!the!power!supply!(separate!chart)! Use!a!multimeter!at!the!leads!of!the!compressor!to!ensure!that!sufficient!voltage!is!reaching!the!machine.!!If!insufficient,!there!may!be!a!problem!with!the!wiring!or!fuse.!See!flowchart!on!Power!Supply!and!BTA!skills!on!Power!Supply.!
6! Does!the!alarm!sound!during!power!up?! Both!display!lights!and!an!audible!alarm!should!sound!after!power!switch!is!turned!on.!
7! Replace!9V!battery! Unplug!machine,!ensure!current!battery!has!correct!polarity,!and!replace!with!a!new!battery!if!necessary.!!


8! Does!the!pump!create!a!sufficient!flow?!
Flow!is!identifiable!by!the!floating!ball!in!the!flow!meter!and!by!bubbles!in!the!humidifier.!To!check!if!there!is!sufficient!flow,!remove!humidifier!and!place!finger!at!air!outlet.!When!outlet!is!covered,!the!ball!should!fall!down.!When!outlet!is!unobstructed!the!ball!should!float.!When!flow!rate!is!set!to!highest!setting!(5!liters!per!minute)!the!ball!should!be!at!its!highest!level!in!flow!meter.!!


9! Is!the!compressor!functioning!correctly?! Check!voltage!into!leads!of!compressor,!and!then!check!flow!rate!at!exit.!If!the!compressor!is!not!producing!max!flow!rate!at!sufficient!voltage!(120V),!the!compressor!is!not!functioning!correctly.!(Proceed!to!13)!10! Clean!inlet!filter! Foam!inlet!filter!should!be!cleaned!weekly!by!washing!with!soap!and!water.!Ensure!filter!is!dry!before!




replacing.!See!BTA!skills!on!Filters!(Plumbing)!!
11! Ensure!that!correct!sized!tubing!is!used!and!that!connections!are!tight.!


Check!that!the!diameter!of!all!O2Ycarrying!tubing!matches!the!machine!inlet!diameters.!Ensure!that!all!connections!are!tight.!Also!ensure!that!the!tubing!being!used!cannot!diffuse!O2.!!See!BTA!skills!on!Connections!(Plumbing)!
12! Look!and!listen!for!leaks!in!tubing! While!air!is!flowing,!listen!for!sound!of!escaping!O2!and!run!hand!over!tubing!to!feel!stream.!If!holes!exist,!tube!should!be!replaced,!not!patched.!See!BTA!skills!on!Leaking!(Plumbing)!
13! Clean!all!O2Ycarrying!tubing! Dirt!or!water!droplets!could!block!the!airway.!See!BTA!skills!on!Blockages!(Plumbing)!14! Clean!compressor! See!BTA!skills!on!cleaning/lubricating!(Motors)!
15! Defective!Compressor:!Consider!replacing! If!compressor!is!clean,!and!is!still!not!producing!correct!flow!rate!it!is!probably!faulty!and!needs!to!be!replaced.!
16! Is!the!O2!Concentration!over!60%?! See!BTA!skills!for!Oxygen!Concentration!Measurement!(MechanicalYCalibration)!
17! Has!the!zeolite!canister!expired?! Zeolite!canisters!should!be!replaced!every!25,000!hours.!The!granules!start!black!and!appear!gray!when!they!are!no!longer!efficient!for!use.!
18! Replace!if!possible! If!available,!replace!expired!zeolite!canisters!with!new!granules.!
19! Check!tubing!for!kinks!or!blockages! Ensure!that!all!O2Ycarrying!tubes!are!elongated!and!not!twisted!or!bent.!See!BTA!skills!on!Blockages!(Plumbing)!
20! Check!for!restrictions!in!muffler!and!resonator.!! A!restricted!muffler!would!prevent!waste!gas!from!exiting!the!system!freely.!Disconnect!the!muffler!and!operate!unit!to!see!if!this!fixes!concentration.!
21! Defective!part:!Consider!replacing!PC!board.! PC!board!could!have!tears!or!kinks!that!may!be!irrecoverable.!!
22! Does!the!machine!run!without!overheating!and!making!excessive!noise?! The!unit!should!not!feel!hot!to!the!touch!or!make!loud!excessive!noises.!
23! Ensure!exhaust!vent!is!at!least!3”!from!wall.! The!exhaust!pipe!should!be!far!enough!away!from!external!obstructions!that!the!waste!gas!can!flow!freely!into!the!atmosphere.!




+

24! Open!unit!and!check!foam! Foam!inside!the!machine!degrades!over!time!and!can!fall!into!compressor.!Clean!and!replace!foam!if!possible.!See!BTA!skills!on!Cleaning!(Mechanical)!
25! Check!muffler!for!damage! Ensure!all!tubing!to!muffler!is!intact!and!connected.!Check!muffler!for!cracks,!damages.!Consider!replacing!if!broken.!
26! Check!that!fan!is!connected!and!installed!correctly! Ensure!leads!to!fan!are!connected!correctly.!Check!that!fan!is!installed!in!correct!direction!of!airflow.!!
27! Device!is!working!properly.! With!sufficient!air!flow!and!O2!concentration,!the!machine!can!be!returned!to!service.!




User Care of Medical Equipment – First line maintenance for end users


43


Troubleshooting – Oxygen Concentrators


Fault Possible Cause Solution

1.





Unit not operating, power failure
alarm sounds



No power from mains socket







Concentrator circuit breaker has
been set off.

Electrical cable fault



Check mains switch is on and
cable inserted. Replace fuse with
correct voltage / current if blown.
Check mains power is present at
socket using equipment known to
be working. Contact electrician
for repair if required.

Press reset button if present


Try cable on another piece of
equipment. Contact electrician
for repair if required.



2.



Unit not operating, no power
failure alarm



Alarm battery dead



Replace battery (if accessible)
and test as above



3.



No oxygen flow



Flow not visible



Tubes not connected tightly


Water or matter blocking the
oxygen tubing

Blocked flow meter or humidifier
bottle





Place tube under water and look
for bubbles. If bubbles emerge
steadily, gas is indeed flowing

Check tubing and connectors are
fitted tightly

Remove tubing, flush through and
dry out before replacing

Replace meter / bottle or refer to
biomedical technician



4.



Temperature light or low oxygen
alarm is on



Unit overheated or obstructed



Remove any obstruction caused
by drapes, bedspread, wall, etc.
Clean filters.
Turn unit off and use backup
oxygen system. Restart unit after
30 minutes.

Call biomedical technician if
problem not solved.



5



Electrical shocks



Wiring fault



Refer to electrician





User Care of Medical Equipment – First line maintenance for end users


44


User Care Checklist – Oxygen Concentrators



Daily

Cleaning



9 Remove any dust / dirt with damp cloth and dry off

9 Fill humidifier bottle up to marker with clean distilled water




Visual checks



9 Check screws, connectors, tubes and parts are tightly fitted



Function
checks



9 Check oxygen flow before clinically required






Weekly

Cleaning



9 Wash filter in warm water and dry. Replace if damaged

9 Clean humidifier bottle thoroughly and dry off



9 Remove dirt from wheels/any moving part




Visual checks



9 Replace humidifier bottle if covered with limescale.

9 If mains plug, cable or socket are damaged, replace



Function
checks



9 Run machine for two minutes and check no alarms occur

9 Check (see bubbles) that flow rate varies with flow control







Every six months
Biomedical Technician check required






** 5.*Resources*for*More*Information*about*Oxygen*Concentrators****Featured*in*this*Section:***** Skeet,'Muriel'and'David'Fear.'“Oxygen'Concentrators.”'Care%and%Safe%Use%of%Medical%Equipment.'VSO'Books,'1995.''*' Wiethöner,'F..'“Oxygen'Concentrators.”'Retrieved'From:'http://www.frankshospitalworkshop.com/equipment/oxygen_concentrators_equipment.html'*''''* *'''''




Resources*for*More*Information:'*''Internal*Resources*at*library.ewh.org:*For*More*Information*about*oxygen*concentrators,*please*see*this*resource*in*the*BMET*Library!*' 1. Skeet,'Muriel'and'David'Fear.'“Oxygen'Concentrators.”'Care%and%Safe%Use%of%Medical%Equipment.'VSO'Books,'1995.''''External*Resources:*' 1. Oxygen*Concentrator*Training*Course:*'• This'website'provides'a'short'overview'of'the'background'of'oxygen'concentrators,'how'to'use'an'oxygen'concentrator,'safety'procedures,'and'oxygen'concentrator'diagrams.'Wiethöner,*F.“Oxygen*Concentrators.”*Retrieved*From:*http://www.frankshospitalworkshop.com/equipment/oxygen_concentrators_equipment.html''''''




Oxygen*Concentrator*Bibliography:''''Cooper,'Justin'and'Alex'Dahinten'for'EWH.'“Oxygen'Concentrator'Preventative'Maintenance.”'From'the'publication:''Medical%Equipment%Troubleshooting%Flowchart%Handbook.'Durham,'NC:'Engineering'World'Health,'2013.'''Cooper,'Justin'and'Alex'Dahinten'for'EWH.'“Oxygen'Concentrator'Troubleshooting'Flowchart.”'From'the'publication:'Medical%Equipment%Troubleshooting%Flowchart%Handbook.'Durham,'NC:'Engineering'World'Health,'2013'''Developing'World'Healthcare'Technology'Laboratory.'“Oxygen'Monitors.”'From'the'Publication:'“Biomedical'Technicians'Training'Program,'Session'3'v2,'Special'Topics:'Cardiac'Equipment.”'Engineering%World%Health,'March'1,'2011,'p.'115^159.'''Developing'World'Healthcare'Technologies'Laboratory.'“Oxygen'Concentrator'Measurement.”'From'the'publication:'Biomedical'Technician'Assistant'(BTA)'Skills,'Duke'University:'DHT'Lab,'2011.''.'Malkin,'Robert.'“Oxygen'Concentrators.”'Medical%Instrumentation%in%the%Developing%World.'Engineering'World'Health,'2006.''* Skeet,'Muriel'and'David'Fear.'“Oxygen'Concentrators.”'Care%and%Safe%Use%of%Medical%Equipment.'VSO'Books,'1995.''* Strengthening'Specialised'Clinical'Services'in'the'Pacific.'User%Care%of%Medical%Equipment:%A%first%line%maintenance%guide%for%end%users.'(2015).''' Wiethöner,'F.“Oxygen'Concentrators.”'Retrieved'From:'http://www.frankshospitalworkshop.com/equipment/oxygen_concentrators_equipment.html'*Wikipedia.'“Oxygen'Concentrator.”'Wikipedia,'p.'1^5.'Retrieved'from:'https://en.wikipedia.org/wiki/Oxygen_concentrator'* ''*




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