# Oxygen tank vs. compressor question **URL:** \ **Category:** Factual Questions\ **Created:** [July 31, 2006, 5:25pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741 "2006-07-31T17:25:54Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![ratatoskK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ratatoskk/32/2987_2.png) [@ratatoskK](https://boards.straightdope.com/u/ratatoskK)\ **Post date:** [July 31, 2006, 5:25pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/1 "2006-07-31T17:25:54Z")
My friend’s mother is in a nursing home and recently had to start using oxygen. In her room is an oxygen compressor that runs on electricity. This has a long tube that eventully runs into her nose, and that’s the source of oxygen she uses while she’s in her room. When she’s moving around the place – to the dining room, etc. – she has an oxygen tank that she moves around with her. Same arrangement with the tubes, but she’s mobile. This may sound like a very dumb question, but – what does the compressor do? Does it actually manufacture oxygen? Or does it just contain oxygen and pump it out? If it just contains oxygen, how is that different in principle from just using an oxygen tank? Tha compressor makes a noise, so I assume it must be doing something, but I just don’t know what. The tank, on the other hand, it totally silent, as you’d expect, it’s just oxygen under pressure with a valve on it. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [July 31, 2006, 5:52pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/2 "2006-07-31T17:52:49Z")
I’d hazard a guess she’s on some sort of CPAP or BiPAP arrangement when she’s in her room, and switches over to plain ol’ oxygen when mobile. The difference is that CPAP/BiPAP pressurizes the airway a bit (It’s most commonly used as a way to manage obstructive sleep apnea) and the plain oxygen doesn’t pressurize the airway. ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [July 31, 2006, 5:54pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/3 "2006-07-31T17:54:21Z")
It concentrates oxygen from the air by removing nitrogen. [Some info.](http://www.fsm.ac.fj/sms/Anaesthesia/WFSA/html/u01/u01_009.htm) ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [July 31, 2006, 7:05pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/4 "2006-07-31T19:05:15Z")
> [@yoyodyne](#): > > It concentrates oxygen from the air by removing nitrogen. [Some info.](http://www.fsm.ac.fj/sms/Anaesthesia/WFSA/html/u01/u01_009.htm) Interesting technology. Can something like that be used in conjunction with automotive emissions to burn fuel more cleanly and reduce NOx? ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [July 31, 2006, 7:40pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/5 "2006-07-31T19:40:58Z")
A 5 liter/min machine is standard and costs about $1000. A 4 liter engine at 4000 RPM would take in about 8000 lpm of air, or 1600 liters O2, so it’d be adding about 5/1600 or increasing the O2 by 0.3%. Not enough to matter I suspect. ---
**Author:** ![ratatoskK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ratatoskk/32/2987_2.png) [@ratatoskK](https://boards.straightdope.com/u/ratatoskK)\ **Post date:** [July 31, 2006, 9:15pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/6 "2006-07-31T21:15:47Z")
That’s interesting info, thank you very much!! 🙂 ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [July 31, 2006, 9:26pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/7 "2006-07-31T21:26:49Z")
Are there any hazards from all the nitrogen being dumped into the air? My grandmother had one, and since it ran so hot, they kept it in a back (unused) bedroom. My understanding is that the room would become very nitrogen rich after not very long. Would that have posed any sort of risk? ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [July 31, 2006, 9:41pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/8 "2006-07-31T21:41:30Z")
> [@Joey P](#): > > My understanding is that the room would become very nitrogen rich after not very long. That’d render the device ineffective. You can’t suck oxygen out of a room that deosn’t contain any. ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [July 31, 2006, 9:51pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/9 "2006-07-31T21:51:25Z")
5 lpm is about what two people doing moderate exercise would use up. I don’t have any room in my house so tightly sealed that I would worry that two people exercising in it would suffocate. And as Squink mentioned, if the O2 is getting depleted it would be a self-limiting process. ---
**Author:** ![Alive\_At\_Both\_Ends](https://avatars.discourse-cdn.com/v4/letter/a/73ab20/32.png) [@Alive\_At\_Both\_Ends](https://boards.straightdope.com/u/Alive_At_Both_Ends)\ **Post date:** [July 31, 2006, 10:00pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/10 "2006-07-31T22:00:44Z")
> [@Joey P](#): > > Are there any hazards from all the nitrogen being dumped into the air? My grandmother had one, and since it ran so hot, they kept it in a back (unused) bedroom. My understanding is that the room would become very nitrogen rich after not very long. Would that have posed any sort of risk? Only from lack of oxygen. The atmosphere is 80% nitrogen, so it clearly isn’t poisonous in itself - we’d all be dead if it were. But you can’t survive on air without any oxygen in it. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [July 31, 2006, 10:06pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/11 "2006-07-31T22:06:42Z")
> [@Squink](#): > > That’d render the device ineffective. You can’t suck oxygen out of a room that deosn’t contain any. :smack: I meant to ask that too. ---
**Author:** ![ratatoskK](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ratatoskk/32/2987_2.png) [@ratatoskK](https://boards.straightdope.com/u/ratatoskK)\ **Post date:** [July 31, 2006, 10:12pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/12 "2006-07-31T22:12:03Z")
Other than the requirements of the device – what about someone hanging about in the room? How much nitrogen would be concentrated? (I guess that’s a silly question because the room isn’t hermetically sealed… 😕 ) ---
**Author:** ![Alive\_At\_Both\_Ends](https://avatars.discourse-cdn.com/v4/letter/a/73ab20/32.png) [@Alive\_At\_Both\_Ends](https://boards.straightdope.com/u/Alive_At_Both_Ends)\ **Post date:** [July 31, 2006, 10:24pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/13 "2006-07-31T22:24:15Z")
> [@ratatoskK](#): > > Other than the requirements of the device – what about someone hanging about in the room? How much nitrogen would be concentrated? > (I guess that’s a silly question because the room isn’t hermetically sealed… 😕 ) If the room was hermetically sealed, then no nitrogen would be “concentrated”. This device doesn’t \*create \*nitrogen, so there can never be more nitrogen in the room than was there to start with. ---
**Author:** ![Stainz](https://avatars.discourse-cdn.com/v4/letter/s/ecd19e/32.png) [@Stainz](https://boards.straightdope.com/u/Stainz)\ **Post date:** [August 1, 2006, 2:39am UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/14 "2006-08-01T02:39:26Z")
The concentrator produces “air” that is more oxygen-rich than room air, but less than a cylinder or liquid O2 system. Concentrators are good for nighttime and sitting around, but for more active patients, cylinders or liquid O2 systems are the way to go. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [August 1, 2006, 3:04am UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/15 "2006-08-01T03:04:16Z")
> [@Alive At Both Ends](#): > > If the room was hermetically sealed, then no nitrogen would be “concentrated”. This device doesn’t \*create \*nitrogen, so there can never be more nitrogen in the room than was there to start with. Actually, the nitrogen would be concentrated. It’s just backwards. Instead of adding nitrogen, you’re subtracting oxygen. So in a closed room (not hermetically sealed, but closed nonetheless, would it become an issue after a while? ---
**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\ **Post date:** [August 1, 2006, 3:43am UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/16 "2006-08-01T03:43:00Z")
> [@Joey P](#): > > Actually, the nitrogen would be concentrated. It’s just backwards. Instead of adding nitrogen, you’re subtracting oxygen. > > So in a closed room (not hermetically sealed, but closed nonetheless, would it become an issue after a while? Reduce the oxygen concentration enough and sure, it will become an issue. Exactly when it does is hard to tell without knowing the infiltration rate of air from outside the room, how much circulation you have naturally in the house, etc. Some rooms might be much more dangerous than others. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [August 1, 2006, 4:21am UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/17 "2006-08-01T04:21:07Z")
Let me rephrase this then. Suppose I was getting one of these machines. Would the manufacturer warn against keeping it in an enclosed room? ---
**Author:** ![Alive\_At\_Both\_Ends](https://avatars.discourse-cdn.com/v4/letter/a/73ab20/32.png) [@Alive\_At\_Both\_Ends](https://boards.straightdope.com/u/Alive_At_Both_Ends)\ **Post date:** [August 1, 2006, 8:09am UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/18 "2006-08-01T08:09:57Z")
> [@Joey P](#): > > Actually, the nitrogen would be concentrated. It’s just backwards. Instead of adding nitrogen, you’re subtracting oxygen. You’re subtracting oxygen, true - but the percentage of nitrogen in the air remains the same. Remember, your lungs are taking in the oxygen from the air (whether directly or via the concentrator, it doesn’t matter) and replacing it with carbon dioxide. In the long term the air in the room would be 80% nitrogen and 20% carbon dioxide (except that you’d be dead long before the oxygen level reached zero, but never mind). The point is that the nitrogen levels are unchanged at 80%. ---
**Author:** ![The\_Flying\_Dutchman](https://avatars.discourse-cdn.com/v4/letter/t/9fc348/32.png) [@The\_Flying\_Dutchman](https://boards.straightdope.com/u/The_Flying_Dutchman)\ **Post date:** [August 1, 2006, 1:08pm UTC](https://boards.straightdope.com/t/oxygen-tank-vs-compressor-question/366741/19 "2006-08-01T13:08:48Z")
> [@Joey P](#): > > Let me rephrase this then. > Suppose I was getting one of these machines. Would the manufacturer warn against keeping it in an enclosed room? This is one of the funniest GQ threads I’ve ever come across. No one ever has been concerned about sleeping in an enclosed room. The little old lady and her machine are consuming no more oxygen per minute than when she was a young teenager without the benefit of the machine. Her lover should have no problem at all. I see **Alive** has addressed the nitrogen concentration issue.