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A Guide to Understanding Pulse Flow Settings on Portable Oxygen Concentrators

by | Jun 25, 2013 | Featured, Learn | 114 comments

One of the most confusing aspects of portable oxygen concentrators (POCs) is the pulse settings. Are they the same as continuous flow settings? Is there a difference in the setting from one POC to another? I am going to provide a detailed response to these common questions. Be warned! Since this is such important information, this post is longer than usual because I wanted to be sure all the information is in one place.

On an oxygen cylinder or home oxygen concentrator, a setting 3 LPM provides 3 liters per minute, or 3,000 milliliters, of actual oxygen output. However, the average breathing rate is 20 breaths per minute, or once every 3 seconds. Therefore, an oxygen user only inhales about 1/3 of the output, or 1,000 mL. The science and math behind an oxygen conserver recognize that 2/3 of the oxygen is wasted, so if it is provided only when the user is inhaling, the oxygen can be conserved. When an oxygen conserver is used on an oxygen cylinder, it simply makes the oxygen last longer; when put into a portable oxygen concentrator (POC), it allows the unit to be smaller and the batteries to last longer.

The amount of oxygen output and the actual amount a patient receives on the various pulse settings depends on several factors.


The first is the conserving ratio of the conserver that is used. Conservers use a 3:1 to 6:1 ratio, with the 3:1 ratio providing the largest amount of oxygen, and 6:1 providing the smallest amount of oxygen. When a conserver is used on an oxygen cylinder, a 3:1 ratio will allow the cylinder to last 3 times longer; a 6:1 ratio conserver will allow the cylinder to last 6 times longer.

In simplest terms, a conserver with a 3:1 ratio provides, in pulse doses, 1/3 the amount of the oxygen of the setting used. At 3 LPM, it provides 1 LPM, or 1,000 mL – the same amount of oxygen the average person would naturally inhale at 20 breaths per minute! I have provided a table of the pulse flow output using various conserve ratios:

 1 LPM
333 mL667 mL1,000 mL
250 mL500 mL750 mL
200 mL400 mL600 mL

Seems pretty straightforward, but it gets more complicated.


Another factor that determines oxygen output is the delivery method of the conserver. There are actually five common delivery methods:

  • Pulse – this method delivers a fixed amount of oxygen each time it detects inhalation. As soon as it delivers the oxygen, it stops until the person takes another breath. All electronic conservers use this method of delivery.
  • Demand – this method delivers oxygen as soon as it detects inhalation and then uses continuous flow until the user exhales. Dual-lumen conservers use this delivery method.
  • Hybrid – this method delivers a pulse at the beginning and then uses declining continuous flow until the user exhales. Many pneumatic conservers use this method.
  • Minute Volume – this method delivers a fixed amount of oxygen per minute. The amount of oxygen delivered with each breath depends on the breathing rate of the user. Slower breathing rate equals larger amount of oxygen per breath; faster breathing rate equals smaller amount of oxygen per breath.
  • Uniform Pulse – this method delivers the same amount of oxygen with every breath, regardless of the breathing rate. Slower breathing rate equals less oxygen over the course of a minute; faster breathing rate equals more oxygen over the course of a minute.

Many people interested in a POC already use a conserver on their oxygen cylinders. Let’s look at some popular conservers:

  • Chad Evolution – 5:1 ratio, electronic conserver, pulse delivery, uniform pulse delivery up to 40 breaths per minute
  • Chad Bonsai – up to 6:1 ratio, pneumatic conserver, hybrid delivery, uniform pulse delivery up to 40 breaths per minute
  • Drive SmartDose – unknown ratio, electronic conserver, pulse delivery, uniform pulse delivery
  • Invacare Element – 3.5:1 ratio, pneumatic conserver. uniform pulse delivery up to 40 breaths per minute
  • Medline EconO2mizer – 5.7:1 ratio (at 2 LPM), pneumatic conserver, hybrid delivery

Now let’s look at popular portable oxygen concentrators. First, some POCs provide both continuous and pulse flow options, while some only offer pulse flow. When not in continuous flow, all POCs use an electronic conserver that is built into the unit, thus all POCs use a pulse delivery method. Since actual conserve ratios are not provided by the manufacturers, I am giving a rough ratio based on the detailed information of oxygen delivered per breath found at OxiMedical.com.

  • DeVilbiss iGo, Invacare Solo2, Oxlife Independence, SeQual Eclipse 3 – all of these units provide roughly a 3:1 ratio, uniform pulse delivery (I am not certain if this is up to 40 breaths per minute; however, I have never heard of anyone out-breathing one of these larger, more powerful POCs)
  • Respironics SimplyGo – roughly a 4:1 ratio, uniform pulse delivery up to 40 breaths per minute for setting 1-4, 30 breaths per minute for setting 5, and 20 breaths per minute for setting 6
  • Respironics EverGo (the SimplyGo’s predecessor – discontinued, but still available from some dealers) – roughly a 4:1 ratio, uniform pulse delivery up to 20 breaths per minute for setting 1-4 and up to 15 breaths per minute for settings 5-6 (patient can easily out-breathe the unit at settings 5 and 6 when breathing faster than 20 breaths per minute)
  • Inogen One G2 and G3, Invacare XPO2 – roughly a 5:1 ratio, minute volume delivery
  • AirSep FreeStyle, LifeChoice Activox – roughly a 6:1 ratio, minute volume delivery

When all is said and done, most people can use the SAME pulse flow setting as they do continuous flow setting. Some find that they need to bump up the setting a notch or two, especially on the smaller POCs that have a 5:1 or 6:1 ratio. Since so many factors contribute to the actual amount of oxygen inhaled, the flow setting number is sometimes just a number. The actual amount of oxygen needed is simply what it takes to raise the blood oxygen percentage to an acceptable level as directed by a physician. A fingertip pulse oximeter provides the numbers that are most important.


  1. Larry

    Very helpful Information.

    • Brenda

      Thank you very insightful Brenda Trail

    • chester castoe

      yes indeed it was very helpful I purchased an inogen 3 an I wonder if it will hurt it run contionus or do I need to buy a stationary uniy to go with it

      • Allison Waters

        While the Inogen One G3 can be run 24/7, I recommend you have a home unit for your sleeping hours. A home concentrator provides continuous flow oxygen, which is usually recommended by doctors, and also has a more robust motor, which will last longer and allow you to not wear out your Inogen prematurely.

      • Gail Walraed

        Please I need help I am on oxygen of 2 liters on my home concentrator I am now getting a portable oxygen concentrator and the therapist says is should be on a setting of 4
        The home is continuous and the portable is pulse

        Why the difference in the settings home 2 portable 4

        Gail Walraed

        • Allison Waters

          The home unit is providing oxygen at a rate of 2 liters per minute, or 2000 mL. The amount of oxygen you actually receive depends on how many times you inhale per minute as well as the length of inhalation, As an example, if you breathe 20 times per minute you inhale once every 3 seconds and would receive about 1/3 of the 2000 mL or 667 mL per minute.

          The portable unit is providing a pulse flow of setting 4. The number 4 is an arbitrary number set by the manufacturer and the amount of oxygen delivered depends on the conserving ratio used by the manufacturer. For instance, an Inogen One G3 at setting 4 provides 840 mL per minute. The amount of oxygen delivered with each breath will be based on your breath rate so if you breathe faster you will receive less oxygen per breath and if you breathe slower you will receive more oxygen per breath (the unit tracks your breath rate and makes adjustments accordingly).

          The setting you need can best be determined by using a fingertip pulse oximeter at the various pulse flow settings to see which setting will provide enough oxygen to keep your blood saturated at the level recommended by your doctor.

  2. Jim Gloudemans

    If one uses pulse mode while sleeping, and inhalation becomes less pronounced in deep sleep, what do the POCs do — does the sleeper still get oxygen?

    • Allison Waters

      All POCs have a built-in No Breath Alarm. Units that offer pulse and continuous flow will alarm, will alarm and then switch to continuous flow mode if no breath is detected. Units that are pulse only will alarm. This alarm usually wakes people up and they will receive oxygen when they begin breathing properly through their nose. The Inogen One G3 will alarm and then switch to auto pulse mode. In this mode, it will deliver oxygen, but it will most likely not be timed with the user’s breathing so very little oxygen may actually be inhaled.

      • Ricky J Bacon

        Does the use of an Oxy-mask 1125-8 increase the ability of a G3 to provide low flow need during sleep?

        • Allison Waters

          The OxyMask would not provide sufficient negative air pressure on inhalation to trigger the delivery of oxygen on a pulse-only unit like the Inogen One G3. Masks can only be used with continuous flow oxygen delivery.

  3. Mark johnson

    I have a devilbiss IGo. When using pulse it inevitably cannot detect my inhale and switches to “full” or constant mode. Their tech person suggested I try a flared canula. I did and it did work for about 30 seconds longer before auto switching to constant flow. He advised if it did not work, my inhale was not strong or sudden enough to trigger a pulse delivery. My plumenary doctor agreed this was a likely cause for the performance failure.
    My question is; if this happens with the IGo will it likely happen with other portable o2 machines and/or canisters? Are there any machines that are more likely to detect my inhales than my IGo?
    I need O2 for treatment of sleep time sleep apnea. I need O2 for camping out as my business calls for me to be in the field sleeping overnight away from power. Locations for my work are sometimes well away from a place I can use a camping trailor with it’s power source.

    • Allison Waters

      With regard to your current set-up, how long is the tubing that you are using? If you are using more than 7 feet, I recommend shorting it up to 7 feet while in pulse flow. The less distance there is the easier it will be to trigger the pulse.

      If your cannula/tubing is already short, then you may want to try the SeQual Eclipse. It has an adjustment for breath sensitivity not found on any other unit. It may work well for you.

    • W Bell

      I have used Air-Sep free style for years for my portable. The pulse activation is sensitive enough to pulse during conversation. I have now out demanded my Air Seps so am looking for an alternative portable for extended periods. For my 24/7 needs I have changed to liquid. No power required, smaller portable cylinders are available for multiple day camping trips and the smallest portable unit gave me 9 hours per fill when I was using two liters. Liquid frees up a lot of situations to where I need a POC for flying and other times I do not have my own transportation. Not every supplier provides liquid, but usually one exists in a service area. Wally

  4. Kelly

    I have been using a Bonsai POC on tanks and set the LPM at 6 when mowing and such. I just bought an Inogen g2 and when it is set on 6(the cash patient model goes to 6) it is not even close to enough. I don’t think I am an extreme need patient and am surprised the Inogen gives so little Oxygen. I can’t imagine very many people could use the g2 successfully and hate to pay the price if I can only use it when flying. I need a portable for flying and this one will work but is there a better solution? I would like to do away with the tanks and just use a portable concentrator.

    • Allison Waters

      This is a great example of what I explained in the article above. The Bonsai conserver that you use on your tanks provides a Uniform Pulse up to 40 breaths per minute; while the Inogen One G2 provides Minute Volume Delivery. Thus, when you breath faster during activity, such as mowing, the Bonsai can keep up with your breathing rate and provide more oxygen when you need it. On the other hand, the Inogen is going to provide a consistent amount of oxygen per minute and cannot accommodate a faster breathing rate. You actually receive less oxygen during heavy activity with the Inogen unit than with a Bonsai conserver. For patients with lower oxygen needs, the Inogen provides higher flow settings to accommodate higher breathing rates during activity. However, if your oxygen needs are higher to begin with (4 or above), a unit such as the Inogen does not give you much “breathing room.”

      The Inogen One G2 is the most powerful pulse only unit available. For increased oxygen at the higher pulse settings, a larger, more powerful unit, such as the SeQual Eclipse or eQuinox would be necessary.

      • David McLane

        Thanks Allison. For some reason I never made the distinction about settings on tank conservers as opposed to POC delivery settings. It’s now obvious to me that a regulator like my Easypulse5 at a 4 will be able to deliver more than my G3 POC at 4 on heavier exertion with more frequent breaths per minute. It also tells that when I plan some heavier activity I might want to temporarily go to tanks.

    • Mark L. Pearson

      I cannot speak directly to your situation but I have found out what helps me when on pulse on a concentrator and getting insufficient oxygen. I learned that I have to slow down a bit, to take deeper breaths and ensure I am using a pursed lips breathing technique I learned in pulmonary re-hab.

      I get odd looks from people at work and airports but they have no idea. Attitude is everything and I look past the looks and sometime comments. I am confident that most people would just give up put in the situation I am in. I plan on continuing to work and travel with no self imposed end in sight.

      Best of luck in your situation, and I hope this helps you.

  5. Mike

    Thanks for providing all of the information. I will be flying for the first time with my
    Inogen One G3 in about one month. The trip will be from California to Hawaii ( 5 Hrs) so I need to get things correct. Currently I keep my flow setting on either 2 or 3. My Dr. Suggested that it would need to be raised to 4 for the flight.

    My question, does the increased flow sound like enough given the provided information? Total travel time including layovers and plane change will approach 10 hours. With the airlines required 50% reserve! this would require 3, 16 cell batteries minimum. Are you aware of any cost effective solution other than purchasing $6-700 worth of batteries that likely will not be used again? Thanks in advance for your help.

    • Allison Waters

      Most people use the same flow setting while flying as they do on the ground since airplanes are pressurized to around 10,000 ft and POCs can maintain the purity of oxygen at that altitude. However, since your doctor must complete a Physician’s Statement for the flight, the airlines will determine battery need based on the flow setting he/she specifies.

      You may want to look into renting batteries for your flight. I think oximedical will rent batteries for POCs.

    • Ellen H

      Look around, you may be able to rent batteries for the trip.

  6. bud tuss

    I have a inogen one that shows a 02 sensor. Is there a way to reset this. Nothing in manual. Thanks

    • Allison Waters

      If the display says O2 Sensor Fail – See Manual, then it cannot be reset.

      The manual says: “The concentrator’s oxygen sensor has malfunctioned. You may continue to use the concentrator. If the condition persists, contact your equipment provider.”

  7. Les

    Can I please receive some further advice whether the G2 could be used for somebody on 2l/min oxygen who at the same time cannot be on more than 2l/min as he is oxygen driven therefore at risk of coma

    • Allison Waters

      Since the Inogen One G2 is a pulse only unit it will not provide more than 2 LPM on setting 2. On continuous flow, if a person breathes 2 LPM at one breath every 3 seconds (20 breaths per minute) they would receive only 1/3 of the 2000 mL, or 667 mL per minute. The Inogen provides a maximum of 420 mL at setting 2. Of course, a doctor’s evaluation would be deciding factor.

  8. Mark

    Is there a POC that will deliver 6 LPM on continuous flow? If not how do you convert the 6 PLM to a pulse rate?

    • Allison Waters

      The highest continuous flow of POCs on the market today is 3 LPM; however, the Oxlife Independence will soon provide 4 LPM. Generally a person would use the same pulse flow as continuous flow, particularly at low flows such as 1 or 2 LPM. However, at higher flow settings for 4 LPM or more, a POC may not be able to keep up with the breathing demand of the user. Thus I would not recommend a pulse only unit such as the Inogen One G2 even though it provides pulse settings up to 6. Instead, a SeQual Eclipse or SeQual eQuinox, which are the most powerful units on the market, would be your best bet for providing high pulse flows. Both units provide continuous flow up to 3 LPM, regular pulse settings up to 6, and super settings up to 9. Ultimately, a fingertip pulse oximeter will be needed to test the patient for adequate oxygen saturation while using a pulse flow on a POC.

  9. Diane Vicorino

    I am so confused about the POC. I am looking at a Inogen One G3 and trying to figure if it would be adequate for me. I have been prescribed OX for exertion only. I do not need for resting or sleeping. I am currently using a M6 canister with pulse deliver at 2 LPM. I just don’t like hauling all these canisters around and makes me nervous leaving them in the car. Can you tell me if the Inogen G3 would work for me. I counted my breaths and came up with about 17 per minute.

    • Allison Waters

      It sounds like the Inogen One G3 would be very suitable for your needs. It provides pulse only up to setting 4. At setting 2, the small battery would last 4 hours and the large battery would last 8 hours. However, be sure to purchase your unit from a company that allows you to return the unit without penalty just in case it does not work. OxiMedical offers a no-penalty return within 10 days.

    • Eugene Jarrett

      I used an Inogen One G3 for 2 years. I do not think it is adequate for anyone who really needs oxygen therapy. And they are completely useless on a airline flight.

  10. Sam

    Thanks for posting answers to concerns about POCs. Please explain warm up time and what oxygen is available then. Thank you

    • Allison Waters

      Since portable oxygen concentrators do not store any oxygen, they do not have a full capacity of oxygen to supply immediately upon start-up. The warm-up is the time during which the machine begins filtering air and concentrating the oxygen. It usually takes only a few minutes for the oxygen to achieve maximum purity; however, most manufacturers allow for 10 minutes for warm-up before alarming in the event there is an issue and the unit does not produce the specified purity. During the warm-up the purity is gradually increasing; however, manufacturers do not provide specification of purity during this time.

  11. Alaa Alnajjar

    Dear Allison,
    my mom is 78 years old and she was prescribed a POC ,she uses a 3L/min during wakefulness and 4L/min during sleep.
    she has a an oxygen machine that she uses when she is in the house but she needs a portable concentrator to use when she goes out . i showed her the simplygo but she thought it was big and heavy for her .
    do you think the inogen one g3 is good for her?

    • Allison Waters

      It sounds like the Inogen One G3 would be a good fit for your mom. It provides up to pulse setting 4 and weighs 5 pounds, so it should provide enough oxygen for her needs and be light enough to carry (it’s half the weight of the SimplyGo). Be sure to find a good dealer that will let you exchange or return the unit if it does not work for her.

  12. George N Gray

    Purchase of an INOGEN ONE G3

    Good day Angela Waters
    I’m in the process of buying the above POC as I suffer from COPD and require it so that I can travel into the Drakensberg Mountains, and up to Johannesburg which is 6000’-00” above sea-level, where there is 20% less oxygen in the air.

    There appears to be a minor problem in that I am now trying out my second POC of this type, and find that when I come under stress, ie walking up hills, riding an exercise bicycle the green light and the puff of oxygen frequently occur at the wrong time, on occasions when I’m still breathing out. I tend normally to breathe slowly and reasonably deeply as I used to play rugby, and having resided in Johannesburg I found that this was the best method to breathe. Shorter breaths leads to panting etc while the longer deeper breaths assist to control my pulse rate. I’m now 77 years of age and suffer from COPD and AF which is under control. At sea level where we currently reside, I can manage fairly well but the heat and humidity does cause me some problems.

    As this is the second trial new machine I conclude that I must be doing something wrong. Also note that after cycling on the exercise bicycle with virtually no load on the pedalling, with the POC set at 3, I finish after 5Kms and walk through to the lounge and check my O2 % and pulse rate. The O2 % was 92/93 pulse in the mid 80’s I can also achieve those figures without the POC but as I stated I require assistance oxygen when I leave the coastal area of try to rush myself.

    Can you please consider this matter and possibly advise me as all comments would be most helpful.

    Your Area Staff are excellent and provide a great service but as this is the second attempt I thought that perhaps the Manufacturer’s would be of assistance to me.

    • Allison Waters

      Inogen’s technical service manual provides the following information about the trigger sensitivity:

      “The conserver will trigger when the negative pressure at the internal sensor reaches 0.12 cm H2O (+/- 20%). This low trigger sensitivity allows for breath detection of very shallow breathing, but may also result in the occasional trigger due to motion of the cannula or motion of the concentrator. The trigger sensitivity may vary.”

      If the conserver is triggering falsely only occasionally then there is nothing to be concerned about. However, if it consistently triggers falsely then it is possible that the unit has a faulty trigger sensor.

      The best test of POC efficacy is satisfactory blood oxygen levels; however, since you are able to achieve good O2 % without the unit, we really won’t know for certain if the unit is working properly until you are able to travel to high altitude environments.

  13. Joseph Pellenberg

    i am contemplating buying a G2 for out of the house,shopping and travel. I will us my
    non portable unit for in the house. I maintain a reading on my pulse ox of 93 -94 ata setting of 3 or so on my stationary machine. Will the G2 supply me with an equivalent amount?

    • Allison Waters

      The Inogen One G2 is a pulse only unit that provides up to setting 6. You may need to use the Inogen One G2 on a higher setting than you do with a continuous flow unit, but it has enough higher settings to accommodate that. Certainly check with your doctor, but it sounds like the Inogen One G2 would easily provide sufficient oxygen for your needs.

  14. Lola Pappas

    I have pulmonary hypertension and need nocturnal oxygen at 2L/m. I will be travelling overseas and my doctor will complete the physician’s statement required by the airline. I would also like to get your opinion as to whether I can travel using a pulse dose POC and at what setting. If you think yes, would Inogen 1 be a good machine for me to purchase?

    Thank you.

    • Allison Waters

      The key to being able to use a pulse flow is the ability to trigger the pulse by breathing through your nose. Most people have shallow breathing while sleeping or breathe through their mouth and are not able to consistently trigger the pulse while sleeping. However, others do just fine. Knowing your breathing habits while sleeping and discussing it with your doctor will assist you in making a decision.

      If you are able to use a pulse flow unit, then yes, the Inogen One G2 or G3 are good models. If you need continuous flow, then I would recommend the Respironics SimplyGo.

  15. Wes

    Thank you for your insightful information. I would respectfully encourage all who need such useful information to use this site .Thanks again Wes

  16. Kim

    I have a 7yr old niece (who only weighs 30lbs) with CF that is on 24hr oxygen. Right now for portables she has to carry around the cylinder tanks with a pulse regulator (set at 3). Not sure if the pulse flow settings on a POC would be the same. At night she’s on continuous flow of 3lpm. Would a POC work for her? I would really like to get her one as her insurance won’t get her one. It’s easier to carry an extra battery around instead of extra tanks.

    • Allison Waters

      A POC should work just fine for her since she is already used to pulse flow. You’ll want to check the amount of oxygen per breath that her conserver (pulse regulator) is delivering and compare it to what she would receive at the same setting on the POC you choose. You may have to increase the flow setting on the POC to get the same amount of oxygen.

  17. Rosemary Sneeringer

    I have read all of the the responses. Very helpful but here is my situation. I have COPD and have just recently been put on oxygen at a rate of 2. I am continuous flow now. I have a small tank that is pulse and can be turned to continuous flow. But if I do that that it only lasts about 45 minutes. I am not very good at it but now thanks to you I know I need to breathe thru my nose. I have been looking at the Simply to Go. I am 110 lbs. and 5′ 1/2. Inches. 10 lbs. seems really heavy for me . I want to be able to fly and travel, walk etc. What if I cannot adjust to pulse? Then the battery only lasts 2.3 hours. This is scary to me but I value your opinion. Thank you. You

    • Allison Waters

      Since you have a tank that can be used on pulse flow, I recommend practicing with that for several weeks before you invest in a portable oxygen concentrator. You should be able to determine within a couple weeks whether you can get used to pulse flow.

      As for the SimplyGo, yes it is 10 pounds, and I expect it to be difficult for you to carry for more than a few minutes at a time. However, it does come with a wheeled cart so you would be pulling it along more often than carrying it. You may want to try pulling a small suitcase to see if it is too heavy for you. The new SimplyGo Mini is only 5 pounds (half the weight), but it provides pulse flow only and does not provide continuous flow at 2 LPM, which you may need for overnight travel.

      The battery for the SimplyGo last 3.5 hours on setting 2 pulse, but you’ll need extra batteries for travel, especially for flying. Keep in mind that you can use the DC adapter when traveling by car so you don’t have to worry about the battery draining while you’re driving. Airlines require 150% of flight time in battery power, so if you have a 4 hour flight you would need 6 hours of battery time.

  18. Damian Sokol

    I recently got an Inogen G3. My question has to do with sleeping at night. I can set the machine at two or three lpm but when my breathing gets slow and peaceful, the Inogen does not adjust to this low intake and fires off the alarm.

    Is there a way, like a special sensitive canula, that would help?

    • Allison Waters

      You may want to try a flare-tipped cannula. This cannula flares out at the ends, filling your nostrils better, resulting in a more sensitive trigger. Many people find this cannula helpful. If your unit continues to give a no-breath alarm with this cannula, then you will have to switch to another model that provides a continuous flow.

  19. Leonard Norris

    are the inogen 3 and oxygo the same machine, just different names

    • Allison Waters

      Yes, the OxyGo is an Inogen One G3 that has been privately labeled for the company that sells them.

  20. Sabina

    Hi Allison, thank you for your blog and helpful answers.
    I use 2lm oxygen concentrator while sitting and 4lm while walking. I want to travel abroad and would like to hire a pulse oxygen concentrator. I am doing about 42 breathes walking and 26 sitting. Could you help to choose which POC ll be ok for me to hire? I am looking at inogen 2. The companies i contacted just say it gives 4 lpm on setting 4 as i need, but reading your blog i understand it doesnt work that way.

    • Allison Waters

      The Inogen One G2 is the most powerful unit under 10 pounds; however, it may not keep up with your breathing rate while walking. It will consistently produce 840 mL per minute on setting 4, giving 42 mL per breath on setting, but only 21 mL per breath on setting 4. It also provides only a pulse flow and may not be suitable to use while sleeping. It certainly is more convenient to use a smaller unit so you may want to rent a unit for a few days or a week before you travel to test it out and see if it will work for you.

      If the Inogen One G2 does not work, then you will need a larger unit like the SeQual Eclipse 5. It can easily handle your faster breathing rate at the higher flow setting. The drawback is the weight and size – it is 18 pounds.

  21. Sabina

    Dear Allison, thank you very much for your answer. Your posts in your blog saved me a lot of money. Only here i could find the correct information about POC.

  22. Julia

    Hi Alison, I’m doing research for a novel and would love some expert help! Am I right in thinking that the Inogen One has a light to indicate breathing? In other words, does the light flash with each breath? If not, do you know of any other POCs that do?
    Thanks in advance.

    • Allison Waters

      Yes, the Inogen One G3 has a Breath Detection Light that blinks with each breath. It also has an alarm feature, listed in the manual as follows:

      Breath Detection Alert Mode. The Inogen One® G3 will alert with audible and visual signals for “no breath detected” when this mode is enabled and no breath has been detected for 60 seconds.
      At 60 seconds, the device will enter into auto pulse mode and once another breath is detected, the device will exit auto pulse mode and deliver normally on inspiration. The display’s mode indication area will show a bell icon, flashing red light and display message when the alert is enabled.

      Best wishes for your novel’s success!

      • Julia

        You are a star, Alison!! Thanks for your help.

  23. Rex Tribble

    I have ordered a Respironics SimplyGo for my wife. She is currently on the bottled oxygen and uses a setting of 3 for continuous flow and pulse.
    We would only be able to use this machine on pulse mode.
    On their site they state that this unit will work with up to 30′ of oxygen tubing. It does not say whether this is for continuous floe only or not.
    They also state not to use with an extension cord for power.
    Our problem is we do not have power outlets close enough to use without needing either a 10′ heavy duty extension cord or a 7′ nasal cannula with 5′ more tubing added ( 12′ total ).
    Could we get buy with a short heavy duty extension cord without hurting anything?
    If not, do you think a short 5′ extension added to her 7′ nasal cannula would work on the 3 pulse setting?

    • Allison Waters

      Since the manual does not explicitly limit the 30′ oxygen tubing to continuous flow, I would think it can be used for pulse flow as well. I see no problem with your wife using 12′ cannula/tubing. I also suspect the use of a heavy duty extension cord would not be an issue; however, this question is best answered by the factory since they are the one’s who decide your warranty coverage in the event damage is incurred.

  24. Janet

    I am oxygen dependent while sleeping and with any exercise. I use a stationary O2 concentrator @ 2L with my Bipap while sleeping, because of sleep apnea and pulmonary hypertension. I also have emphysema and use a M 6 tank with walking exercise @ 5L pulse dose. I would like to have a POC that would serve my purpose for exercise and also traveling, especially for night use. What POC do you recommend for me?

    • Allison Waters

      The POCs that would meet your oxygen needs are the SeQual eQuinox, SeQual Eclipse 5, or the Oxlife Independence. All of these provide up to 3 LPM continuous flow and 6 or more on pulse flow.

  25. barbara duncan

    I am nervous about taking first flights with POC. I have the Inogen One G3 and plan on taking 2 back to back 3 1/2 hour flights from San Francisco to Philadelphia.

    I have 2 four hour batteries and just spoke to the Inogen support staff about buying extra batteries. One person recommended I buy the new 9 hour battery while another recommended just buying an extra four hour battery and taking all 3 with me to make sure i have the 150% capacity required.

    Do you have any advice? Normally I use oxygen only at night at rate of 2. But i know traveling for hours at the limited oxygen in aircraft can trigger more trouble in breating?

    Thanks for any advice you can offer.

    • Allison Waters

      For a total of 7 hours of flying you need 10.5 hours of battery time. If you will be using setting 2, then the larger battery will last 9 hours but is still not enough by itself to meet the requirement of 150% of flight time in battery capacity. Therefore, you would still need to bring at least one of your smaller 4-hour batteries for a total of 13 hours. Alternately, if you purchase another 4-hour battery, you would have a total of 12 hours, which would meet the requirements. The choice is based on your personal preference considering cost, the number of total batteries you want to bring with you (1 large and 1 small vs 3 small), and whether you would have use for the larger 9-hour battery in the future.

  26. Susan DeMan

    My 82 yr old dad has Pulmonary Fibrosis. Lung capacity at 78%. now using Eclipse POC with continuous 1-2 LPM. (increase to 2 LPM with activity) doing well with O2sat 94-98%.
    He wants to try a pulse, but I am concerned that the pulse mode will not maintain his O2sat above 95%, especially with activity.
    He wants to look at the Imogen G3 or G4.
    He often has to be reminded to nose breathe vs huffing via his mouth.
    Do you have any input for how pulse vs LPM will be effective?

    • allison

      Your dad’s oxygen requirements are low so as long as he learns to breathe through his nose he should do well with pulse flow. Since the SeQual Eclipse that your dad already uses has pulse flow settings available, it would be easy to try pulse flow (under the care of his physician) before investing in another unit. Effectiveness is measured with a fingertip pulse oximeter. Keep in mind that the Eclipse provides the greatest amount of oxygen per breath at each pulse setting and a 2 on one model is not the same as a 2 on another model. While your dad may do quite well with the Eclipse on pulse setting 1 or 2, he may need a setting 3 or 4 on a pulse only unit like the Inogen models, which provide smaller amounts of oxygen at each setting.

  27. vince coyner

    Hi Allison,

    Great piece!!!

    My mother has an Inogen One G2 that goes up to 6. She is currently on 4 continuous. Given that the Inogen is a 5:1, are you saying that if she used the G@ at a rate of 5 that she would probably get as much oxygen as she does at the rate of 4 continuous? I’m not interested in the time while sleeping, but rather during the time driving in a car or pushing a cart in the store.


    • allison

      If an oxygen user breathes 20 breaths per minute on 4 LPM continuous they would receive about 1/3 of the total 4000 mL being produced, about 1333 mL per minute. The G2 provides 1050 mL per minute on setting 5 and 1260 mL on setting 6. Neither of these quite reaches 1333 mL, although most people can use the same setting, or one setting higher, on pulse flow as they do on continuous flow. What a personal actually inhales is dependent on many factors including breath rate, the length of inhalation, timing of the pulse oxygen in relation to inhalation. There is no way to determine the exact setting that will be sufficient to keep blood oxygenated without the use of a fingertip pulse oximeter. The reading on an oximeter is the number that tells you the full story.

  28. kathy ballard

    I have large continuous flow oxygen machine in home. I have 35 ft tubing, as I can move about in my home. I have it set at 3 pm, however I do better when its set to 3 1/2. Is this due to the length of the hose.

    • Allison Waters

      Most home concentrators can provide optimal levels of oxygen with up to 50 feet of tubing so 35 feet should not be a problem. If you do better at 3 1/2 it’s possible you simply need more oxygen. Check with your physician or respiratory therapist to be certain.

      • stewart

        I have used a variety of Portable Oxygen Concentrators with mixed results.
        I find that the world at large is not as aware as we should be inasmuch as the dialed in setting does NOT necessarily correspond to the the LPM flow rate – an important item you first published several years ago.

        Currently I am using LOX, and have vessels at home that get refilled 2x monthly, and a Helios Marathon 850 for my portable use.

        The Helios Marathon has an option of “On Demand” vs. Continuous flow.

        I do not believe, however, that either of the numerical values directly relate to the LPM flow rate, but are merely close (closer than a POC) rate published with the various OEM data . . .

        Stewart M –

  29. Barry Drake

    I have just bought an inogenone G.3 I have a mild degree fibrosis and at the moment have some blood clots. When I walk on setting 5 the G3 seems to get a mind of it’s own and delivers when it wants Which leads to my oximeter giving a low reading after a while. At the moment I need O2 24/7 but have been told that when the clots have gone I won’t be so dependent on O2. I take 18/20 breathes a minute and at the moment sit at rest or sleeping on setting2 . Do you think there is a fault with say the trigger switch or is it my high demand due to the clots at the moment

    • Allison Waters

      While walking, you are probably breathing faster than the Inogen is able to keep up at that setting. In other words, you are out-breathing the machine. I recommend you take your Inogen to your doctor and use it while doing a 6-minute walk test. I look forward to hearing back from you after you visit your doctor.

      • Barry Drake

        Hi Alison. When I spoke to you it was early days and I haven’t been using it very much, and being housebound I have used an indoor one that the hospital here in Malta lets me have for as long as I need. I started feeling much better these past few days and so started to use the inogen machine as I live in a penthouse apartment without a lift and have to negotiate 46 steps to get back up. I had had the same thoughts about my breathing technique out-breathing the machine so have now altered my technique and am now I am going out on a regular basis. So nice to know I can speak to someone with your knowledge, thank you
        Kind Regards

  30. Lorraine

    I don’t know anything about POC’s but purchased a SeQual Eclipse 3 for my Aunt who recently passed. I have listed the POC for sale and the buyer asked me if it can go to 9 on Pulse. The POC does not list a Pulse dose setting higher than 6.0 at a Bolus Size of 96. The chart list Bolus Sizes up to 192 but no Pulse Dose beyond 6.0.

    What is the relationship of Pulse Dose to Bolus Size, and does the Bolus Size of 192 equate to Pulse Dose of 9?


    • Allison Waters

      SeQual programmed the unit to only show bolus size at the higher settings on the display screen, but the bolus size of 192 mL is the equivalent to pulse setting 9 so you can tell the buyer that the unit does indeed go up to setting 9.

      • Caroline Dillon

        So pulse setting 9 is equal to pulse at 9lpm?

        • Allison Waters

          Not exactly. The SeQual Eclipse and SeQual eQuinox provide pulse setting 9 and these units produce 192 mL per breath only up to 15 breaths per minute. Faster breathing rates will result is less oxygen per breath. This is due to the maximum capacity of the units to produce 3 LPM continuous flow which is 3000 mL per minute. So at setting 9 x 15 breaths per minute, the unit is giving 2,880 mL per minute. If an oxygen user requires 9 LPM continuous flow, no pulse flow model will provide sufficient oxygen, even at pulse setting 9.

  31. CJ

    Are there any POCs that use the demand delivery method? I’m currently on 5-6 lpm continuous flow, mainly because I cannot breathe effectively through my nose due to sinus & allergy issues. Previously, when I was on a lower dose of oxygen, I used the Respironics SimplyGo until I reached the point where I was continually out breathing the machine, at which point I was put on the E size tanks at my current usage. I was wondering if I used a mask with a demand or a hybrid machine if it would detect my inhalation through a mask (which I believe I could do at a lower pulse rate & keep my saturation level up)?

    • Allison Waters

      There are models that provide pulse (on-demand) delivery of oxygen. However, using a mask would not provide enough negative air pressure to trigger the delivery of oxygen. Masks can only be used with continuous flow oxygen delivery. Unfortunately, using a pulse delivery requires effective breathing through a nasal cannula.

  32. Roderick Buen


    I’m at 2L in my home oxygen concentrator with 94-95% saturation. I just purchase the Activox 4L and would like to know what setting i should use. i did a trial on me at 2L setting on my activox to make sure i saturate well during my short 2.5 hour flight but my oxygen saturation dropped to 85%

    • Allison Waters

      I cannot advise flow settings as this is determined by your physician; however, it is likely you need to use whatever setting allows you to remain saturated at a satisfactory level.

  33. Joan Wood

    I am buying an Inogen One G4. and concentratror for home use I was doing the 6 minute walk test and it dropped down from 90 to 89. Another time I did it was only 87 . When my breathing dropped to 89 she stopped me and put me on an oxygen tank and I still had trouble breathing but it remained at 90. what does level 2 mean it is it enough oxygen: Is Inogen G4 and the home concentrator enough for me?

    • Allison Waters

      Level 2 is an arbitrary number set by the manufacturer. It is not equivalent to 2 LPM and is not the same from one POC model to another. On the Inogen One G4, it means you are getting 420 mL per minute. As a point of reference, if you breathe 20 breaths per minute on a continuous flow of 2 LPM you would receive about 667 mL per minute. If the setting 2 on the G4 is not providing you with enough oxygen then you may need to test at setting 3 or get with a more powerful model like the Inogen One G3 which provides 5 pulse settings.

  34. John Fagan

    I have a OXYGO (1400-1000) and I would like to know if it is set on a higher flow setting (I am on 2lpm now) does the increase in lpm affect the length of the battery time. I have never tested the battery length but I know I am getting over 4 hours now.

    • Allison Waters

      Yes, the increase in flow setting will decrease the battery time. Roughly, the large battery will decrease about 1 hour and the small battery will decrease about 1/2 hour with each increase in flow setting.


    The pulmonologist prescribed 6lpm. In order to fly on a 2-3 hour flight would the SeQual Eclipse with its 9 pulse level be sufficient?

    • Allison Waters

      If you breathe well through your nose, the Eclipse should provide enough oxygen for you; however, you would need to seek medical advice from your physician who may want to test your oxygen levels while using the Eclipse.

  36. Mike Gracher

    Hi – my mom has an Inogen G2 that just started having the red light come on a couple of minutes after turning it on. She called Inogen up about it. The lady there thought it could be repaired, but after I mentioned on the call (speakerphone on) mom had done 3 things before this started, she said that may be involved and suggested a hard reset. The things mom did was change the pulse rate from 2 to 3, change to a new canola, and took the intake screen off to check it. I had her wash the screen, change the rate back to 2, and try another canola. These attempts seemed to only lengthen the time before the red light came on again. Mom also has never replaced the filter thing behind the canola hookup. Could that be the problem?
    I found a kit on Amazon for that – 2 filters & tool. In the meantime I tried cleaning the filter with a eyeglass cleaning mini towlete used for glasses – has some rubbing alchohol in it. Left it out to dry. The filter did seem to have a slight off-white stain that I am not sure got cleaned or not. She has yet to retry the unit as she has a G4 to use and a floor model OC.
    I searched for this red light problem and a user posted a similar scenario at another place and never got an answer to it, so I eventually found this thread with lots of good info.

    So if the red light still comes on, it’s either get the filter kit, have the unit fixed or she gets another. She likes the G2 because it puts out more than her lighter G4 unit does. G2’s can still be found new, barely.

    • Allison Waters

      When the red light comes on, is it solid or blinking? Also, what audible alarm do you hear (how many beeps)? Finally, when it alarms, there will be a message on the display – what is the message that appears?

  37. Mike Gracher

    3 beeps — solid on — low oxygen

    Took a lot longer to go off this time after the filter disk cleaning try.
    Used to go off quicker.

    I think the G4 uses the same filter as the kit I saw online looks a lot like the one for the G2
    if so, I should get the G2 kit and then can use it for the G4 at least if it’s not the solution.

    • Allison Waters

      The alarm is indicating the oxygen purity is below 82%. It sounds like the sieve columns need to be replaced. This is an internal item on the G2 model so it would have to be sent in for service. Keeping the intake filter very clean and using a lower flow setting will temporarily allow the unit to produce a higher purity for longer periods of time. I would advise against purchasing a G4 filter as it is not the same size as the G2 filter and will not fit the G2 unit.

      If the unit is still under warranty then the sieve column replacement would be covered under warranty. In this case, I recommend you contact the company from which you obtained the unit as they would be able to assist you with a warranty repair.

  38. Mike Gracher

    Probably her moving the setting from 2 to 3 triggered it in the first place.

    No longer under warranty. They did offer a new W for 6 months or one for 2 years – then it would be covered for repairs.
    Her G4 she bought has a lifetime W.

    Thank you for the info.

  39. Gordon VHarmon Harmon

    I have an oxy go (the same as the inogen G3)? I can easily out breath it on a setting of 4 when I am walking. I don’t see any difference in a setting of 5. Am I expecting too much or just leave it at three or four?
    Thank you

    • Allison Waters

      If you are out-breathing the unit at setting 4 then you will not benefit from setting 5 since it will have an even harder time keeping up with oxygen production at the higher setting. Ideally you need a unit that can keep up with fast breath rates, such as the SeQual Eclipse; but unfortunately, it is not as portable as your OxyGo2.

  40. Victor Pacheco

    Excellent article. I’m a new oxygen user, so this is very informative and I look forward to revisiting this site as my needs change and the technology advances. Thank you,

  41. Gordon V Harmon

    I have a G3 for daily use and a DeVibliss for night – both on a setting of 3. I seem to get the same O2 readings with the G3 set on 1 as I do with it set on 3 during the day. . Is less flow better overall for a non-exercise activity?
    Thank you,
    Gordon Harmon

    • Allison Waters

      It is generally recommended that you use the flow of oxygen that will provide the desired O2 readings. Unfortunately, I am unable to provide specific advice and would recommend you speak with your doctor about adjusting your flow settings.

  42. Rich Busby

    Dear Allison, I have an Inogen One G3 for portable use and an Invacare Platinum 10 for home use. The Invacare does fine at home but if I am doing much at all, the G3 does not keep up. I have to stop and let my O2 build back up. What is the best, the biggest O2 producer, I can use outside the home? I usually have a power source available, 120 volt ac or 12 volt dc. My Inogen has 2 small batteries. The Invacare is too heavy and too bulky to take with me in the car or on a motorhome trip (the motorhome has a generator and so does the camp grounds we stay at. My hope is that I can get ready at home on the Invacare and when ready to leave, use the Inogen (this I have done) while driving. The problem is at camp grounds when I do not have the Invacare. If I could get a little more O2 I could handle campsites (taking my time and with a wonderful wife). Would the SeQual Eclipse 5 be a good choice and what is your opinion? You are doing a great service to O2 users, keep it up, Thanks, Rich

    • Allison Waters

      Yes, the SeQual Eclipse 5 is exactly the unit I would recommend. It is the most powerful POC being made, providing up to 3 LPM continuous flow and up to 9 pulse flow settings. Having the capability of producing 3 LPM gives the unit the power to keep up with higher breath rates on the pulse settings so you get much more oxygen at the same pulse flow setting on the Eclipse than you would on the Inogen One G3. To further explain, the Inogen One G3 provides a maximum of 1050 mL per minute so at setting 5, you receive 52.5 mL per breath at 20 BPM, 35 mL per breath at 30 BPM, and only 26.3 mL per breath at 40 BPM. On the other hand, the Eclipse provides a maximum of 3000 mL per minute so at setting 5, you receive 80 mL per breath at 20 BPM, 80 mL per breath at 30 BPM, and only a slight dip to 74 mL per breath at 40 BPM.

      The drawback of the Eclipse is the size and weight. It is considerably larger and heavier than the G3 and cannot be carried over your shoulder. Instead, you would wheel it on a cart. But it is much smaller than your large Invacare unit and sounds perfect for your camping trips.

  43. Alice Marquez

    What setting should my Oxygo be at for 2 Liters? I cant find it on the manual. Than you

    • Allison Waters

      The OxyGo is a pulse only model so I recommend you read the entire article to understand how pulse settings relate to liters. For the short answer, the following is the close of the article:

      When all is said and done, most people can use the SAME pulse flow setting as they do continuous flow setting. Some find that they need to bump up the setting a notch or two, especially on the smaller POCs that have a 5:1 or 6:1 ratio. Since so many factors contribute to the actual amount of oxygen inhaled, the flow setting number is sometimes just a number. The actual amount of oxygen needed is simply what it takes to raise the blood oxygen percentage to an acceptable level as directed by a physician. A fingertip pulse oximeter provides the numbers that are most important.

  44. Susan Green

    Allison, you have the best site I’ve seen. Thank you. I notice, however, you have not mentioned the Inogen One G5. I’ve read the promotional literature and some reviews, it sounds great. Are there any downsides I should be aware of? I like to hike if possible. So far I’ve just used a tank in a backpack. (If I take a deep breath I get two puffs. 🙂 )

    • Allison Waters

      The Inogen One G5 is the latest edition to the Inogen line of POCs. It provides 6 pulse flow settings, making it the most powerful unit of its class. I am not aware of any downsides of the G5 and would recommend it for those who find it meets their oxygen needs. For backpacking, I also recommend a backpack and it will balance the weight between both shoulders.

  45. Michael P Croke

    I am looking for a POC to wear fly fishing (walking) and need to get biggest bang for my buck. I am looking at Inogen G3 or G5. What do you think?



    • Allison Waters

      The Inogen G3 and G5 are very similar. The G5 provides a bit more oxygen, up to 1260 mL/min at Setting 6. And the battery lasts a bit longer on the G5. But the G3 is an excellent machine as well. So if the cost is better for the G3 then don’t hesitate to get it. If oxygen and battery times are appealing and the cost is not prohibitive the G5 is the winner. Either way, I don’t think you can go wrong. With either, I recommend a backpack to keep your arms and free to cast.

      • Michael Croke

        What I didn’t mention is that I have a G3 in need of repair (System error)
        and I can only find one company to repair, but what they do is repair and return with a 975.00 Lifetime Warranty and Service plan. So the diff between a new G5 and my repaired G3 is considerable. So how much is the larger dose of O2 worth.


        • Allison Waters

          The maximum output of the G3 is 1050 mL/min. The larger dose offered by the G5 is only worth it if you need a higher flow setting. If you are currently using 2-3, then having up to setting 5 with your G3 is probably sufficient for the near future. However, if you are already using your G3 at settings 4 or 5, then having the extra setting on a G5 might be the way to go.

          • Michael P Croke

            Thank you ….do you know what the comparison is between an O2 dose on a concentrator vs a conserver on a tank i.e. setting 5 ?


          • Allison Waters

            It would depend on the conserving ratio of the conserver on the tank. I recommend you review this article as I provide information on conserving ratios and provide the ratios for many popular conservers, as well as portable concentrators including the G3. If you don’t see a particular conserver, an internet search for the specifications might be helpful.

  46. Michael P Croke

    Thank you G5 it is.

    Kind Regards

  47. Jerry Richmond

    I get an audible “hiss” on pulse breath on portable canister and wonder if I have turned it on correctly. My O2 numbers hold yet seem to be a bit lower than max. any ideas?

    • Allison Waters

      From your description, it sounds like it’s the normal puff of oxygen that is delivered when using pulse flow. However, I recommend you contact your supplier to confirm.

  48. Savina Helms

    Hello, I could really use some advice. I maintain a 93% sat while I am sitting or relaxing, but when I start to walk, my 0xygen requirement increases to 4 L just to keep my 02 sat at 88-90%. Currently, I miss out on all outings with my family and am mostly stuck at home with my plug in home concentrator and my 4 stupid E cylinders. What POC would you recommend for my 02 needs?

    • Allison Waters

      The smallest and lightest POC that might work for you is the Inogen One G5, which has pulse settings up to 6. If it does not provide enough oxygen for you, then a larger unit that provides a continuous flow setting might be necessary. These would be the Philips SimplyGo or GCE Zen-O.

      • Savina Helms

        Thank you for such a quick response, I really appreciate it.

      • Savina Helms

        Also, what conserving ratio does the G5 use?

        • Allison Waters

          Inogen continues to use slightly better than a 5:1 ratio, providing 210 mL per setting, for a maximum of 1260 mL at setting 6.