DIY Zeolite oxygen concentrator

john bunsenburner · Sun Apr 12, 2009 3:53 am

Well as some of you may know I am planning to build a small oxy-hydrogen welding unit. The overall price should stay under 50$ for construction.
Now I need a reliable oxygen source for my purposes and a chlorate torch just doesn't cut it. Therefore I looked a other alternatives and found out about the oxygen concentrators used in hospitals. They use a mineral(a kind of aluminium silicate) called zeolite to filter out impurities and absorb the nitrogen. Now I know that the zeolite i need(yes there is several types) contains Calcium but I know no more. Perhaps one of you works in a hospital or can otherwise tell me what the exact zeolite I would need is, how much it costs(more or less) and perhaps even where it can be purchased(though that will be hard as I live in switzerland).
Depending on how good zeolite will be for my purposes I will either use it or just buy an O2 tank, or use plain air.
Thanks in advance for your help, comments suggestions and questions, they are all greatly appreciated!

rp181 · Sun Apr 12, 2009 9:21 am

Zeolite is used to refine the oxygen, not get it from the air. As far as i know, those can only absorb so much. In the hospital i volunteer at, there is a HUGE liquid oxygen tank outside, that gets filled by the company periodically (praxair i think). Find a local hospital and ask for a oxygen tank. In my hospital, there are tons of supply rooms, each with around 50 filled oxygen tanks (usually around 3000PSI, with built in reg that allows up to 25 PSI in 1/2 PSI incriminates.

jonnyboy · Sun Apr 12, 2009 9:41 am

Why not use the oxygen you get from your h2 set up ?

I would just get a tank from home depot as it's probably simplest solution.. although do they have home depot in Switzerland?

dudeman508 · Sun Apr 12, 2009 10:01 am

rp181 wrote:Zeolite is used to refine the oxygen, not get it from the air. As far as i know, those can only absorb so much. In the hospital i volunteer at, there is a HUGE liquid oxygen tank outside, that gets filled by the company periodically (praxair i think). Find a local hospital and ask for a oxygen tank. In my hospital, there are tons of supply rooms, each with around 50 filled oxygen tanks (usually around 3000PSI, with built in reg that allows up to 25 PSI in 1/2 PSI incriminates.

Are they free, and could I take the reg of.

john bunsenburner · Sun Apr 12, 2009 10:52 am

Wikipedia on Oxygen concentrators wrote: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 %.

A device of this kind can easyly be built if I find some zeolite.

Wikipedia on Oxyhydrogen wrote:Oxyhydrogen is a mixture of hydrogen (H2) and oxygen (O2) gases, typically in a 2:1 molar ratio, the same proportion as water.[1] This gaseous mixture is used for torches for the processing of refractory materials and was the first gaseous mixture used for welding. In practice a ratio of 4:1 or 5:1 hydrogen:oxygen is required to avoid an oxidizing flame.

I need a ratio of 4-5:1 inorder to have a non oxidizing flame, therefore I built myself a hydrogen generator which is NOT an electrolosis cell, instead it functions using water, scrap aluminium and washing soda.

Now back to the zeolite, where can I get it and for how much?

john bunsenburner · Sun Apr 12, 2009 4:20 pm

I don't mean to double post but i really need answers to this, anyone know anything?

Technician1002 · Sun Apr 12, 2009 5:17 pm

john bunsenburner wrote:I don't mean to double post but i really need answers to this, anyone know anything?

Since the common use is medical, I would start with places that do maintenance on the units. A wikiAnswers has a short rundown on how they work, the purity and life.

http://wiki.answers.com/Q/How_do_home_o ... ators_work

Would switching the in service and regenerating sets disrupt delivery?

***Edit***
The primary use is medical. These may be controlled as prescription medical devices. It may be best to stick to welding supplies. Anything medical is most likely very expensive.

jimmy101 · Sun Apr 12, 2009 5:43 pm

Do you know what Zeolite is used for? Can you think of a way of doing it without the Zeolite?

Zeolite has a limited ability to purirfy oxygen from air. Usually an oxygen generator using Zeoplite has two cylinders, one is actively purifying oxygen from the air while the other is being vented/purged to the air. For small quantities of oxygen this works fine. For larger quantities it is not very efficient. For a small medical application the device costs several thousand dollars and uses about as much power when operating as a kitchen oven.
(for example http://gasairsystems.tradeindia.com/Exp ... rator.html and http://www.arrowheadhealthworks.com/ewot.htm)

I suspect a Zeolite based system is going to be more trouble than it is worth. It'll be safer, cheaper, faster and overall more effective to just get a small welding oxygen tank with regulator, flame arrestor and back flow device. If you use (or build) a "medical type" oxygen generator then you must install some type of backflow and/or flame arrest mechanism since medical generators are not designed to be used with flammable gasses. Any combustable gas the migrates back into the oxygen souce will make the oxygen source a bomb. The flammability limits of most combustable gases when mixed with pure O2 are much wider than when mixed with air.

rp181 · Sun Apr 12, 2009 6:06 pm

You are making this way more complicated than it needs to be. It would be a better choice to buy some O2 from the US. You could have a normal electrolysis cell, with a plastic divider. to collect the gasses seaperatly.

Why would a hospital give away free oxygen tank? The reg is directly screwed in the tank.

john bunsenburner · Mon Apr 13, 2009 1:58 am

Hmm, ok, in that case I guess an oxygen tank and reg will be my way to go. Can any of you tell me in what price range I would be in? Anything else I need to know?

jimmy101 · Mon Apr 13, 2009 2:54 pm

john bunsenburner wrote:Hmm, ok, in that case I guess an oxygen tank and reg will be my way to go. Can any of you tell me in what price range I would be in? Anything else I need to know?

Do you have ~$60?
http://www.thegreathardwarestore.com/Pr ... click=2744
Propane and oxygen cylinders, hoses, regulators, torch.

john bunsenburner · Mon Apr 13, 2009 3:08 pm

I do have 60$, but am not in the USA, no way I will find anythign under 100$ here. I think I will go with plain air.

saefroch · Sat Jan 22, 2011 6:46 pm

The last post on this thread was nearly two years ago. Please read.

alvinfredric · Thu Mar 29, 2012 4:40 am

Hi...I am very interested to Know the information about zeolite granules. How it will help to compressing and filtering air and what is the role of zeolite in oxygen concentrator .Can anyone please explain it with diagrammatically. Thanks.

SimplyGo Portable Oxygen

ramses · Sat Mar 31, 2012 1:02 pm

The Zeolite basically absorbs Nitrogen from the air. The Zeolite is "cleaned" of N2 by pulling a mild vacuum on it. There are usually 2 zeolite cells that the concentrator alternates between for a continuous supply of O2. While one is being used to absorb N2, the other is under vacuum to remove the N2 it absorbed.

The ones I've been around will toggle between canisters once every 5-15 seconds.