oxygen concentrator, pressure swing absorption, system

hi everyone am new here but i feel i am in the correct place. to start with, i am building a furnace to melt metal, i needed to do some welding, so i decided to build my own oxygen absorbtion machine. when complete should be able to process compressed air to oxygen actually its concentrated oxygen. with the pressure swing system, it separates, oxygen and nitrogen, and the trace gases, it can process nitrogen to 98% and above using a molecular zeolite filter, called 13 x, . heres were i could use some wise knowledge, i need some flanges for my machine, i have been all on the net , even today t a local fabricater not small rather large firm however. i thought to myself i could make these myself if i had the tools,(i am a carpenter by trade). so is there anyone on here who can make these flanges or do you reccomend someone. heres the spec.

8"150# raised-face slip on flange i need 2 of these

8"150#raised-face blind flange. thankyou for taking you time to read through.

Paul, you need to tell us where you are in case someone local can help

You should be able to buy pipe flanges like that off the shelf, the ref you give is an american one but if in the UK look for BS10 plate flanges

8" flanges, you'll no doubt want them manufactured from certified material. Like Jason says, simpler (and probably cheaper) to buy off the shelf from people set up to produce these.

Parker Steel have a good range

thankyou for all the replys most appreciated, i am in doncaster south yorkshire,, i will be checking through your suggestions

Hello Paul Jameson

You mention you intend to "build my own oxygen absorbtion machine" That sounds like a very interesting project, Can you elaborate on your design please?

Regards
John

Paul

what sort of flows/pressure and concentration are you expecting from your design?

hello thanks for your interest, , john and bob. firstly my initial concept was to use this system so as to not be purchasing oxygen refills, all i wanted was to do some welding ,brazing without being tied to consumables. so i looked at how, acetylene is produced, and then oxygen, i kind of bumped into it while researching, the design is not my own in fact it is used in a few areas, one being oxygen concentrators used for the medical industry, for people who need purer air , oxygen than the norm, there are also uses by the military, and it is used to produce nitrogen and oxygen, in the nitrogen process oxygen is the waste product with argon and other trace gases, simple process . compressed air is pumped through a zeolite, molecular sieve, to about 120 p.s.i. oxygen or nitrogen depending on your sieve is separated from the air mix, , you can harness either or both,. there is a brilliant design in (Instructables, by imsmoother) full assembly and materials it uses 40 kilograms of molecular sieve, 20 in each reservoir. the creator of this particular model uses it to harness nitrogen, he then goes on and liquidises the nitrogen, very clever, does it on his driveway, however inititialy i want one . i am interested in modifying this design, using smaller materials, it would make more cost effective. so any thoughts would be appreciated, i have just located a supplier for the molecular sieve in the uk, took me ages to find. heres a picture

If you have built a molecular sieve oxygen concentrator then to my mind you are virtually a God. If it is indeed possible, as you suggest, to generate gases and then liquify them in a process that is amenable to home workshop construction, then you are also an alchemist. As a rocket engine man, you have shown me the way to the philosopher's stone.

Hello Paul,

​I was interested to see you post, one item of which you sought some information on.

​Acetylene is produced by the action of water on calcium carbide pellets, it was commonly used in this way on early vehicle lighting. Whether or not you can produce enough to meet the demands of welding, without collecting and compressing the gas, is another matter. Commercially it is stored in pressure bottles fully dissolved in acetone in a porous mass which fills the bottle.

​Without that method of storage under pressure, unstable metal compounds called actylides form with the gas reacting with the storage bottle. These are explosive and will react to shock like nitro glycerine and there were many bad accidents in the early days of acetylene gas welding at the turn on the 18th century when these hazards were not known. If you look at a BOC leaflet you will see acetylene is sold as the dissolved gas.

Regards
Brian

Old oxycons are typically used for surface mixing burners by lamp workers. Ours is a 5l/minute version. They cost around a couple hundred quid from a supplier, or less from a private seller. 10l ones are readily available but rather more expensive. These are all reconditioned ex-medical use, mainly, I would think. They are no longer certified for medical use as the filters are no longer there or compliant.

Oxygen purity can be up to 98%, but performance drops off as the maximum service volume is approached. Down to upper 80s as I recall. Ours is low pressure, so not sure if it would work with an internal mixing torch but I may try it sometime. I'm not too keen on compressing oxygen, but a diapragm compressor might make enough pressure for a short run from a well cleaned compressor tank?

Edited to add that I would not contemplate compressing acetylene on a home scale.  Too dangerous.  Triple carbon-carbon chemical bonds are not very stable!

Edited By not done it yet on 09/10/2016 11:10:19

I think this is a little pessimistic. I don't think Paul intends to build the whole thing from scratch. You could buy the difficult bits and then add your own plumbing and insulation etc.

For example, following Paul's imsmoother reference I found a description of the home Nitrogen liquefying plant. At the heart is a commercial compressor of the type used to recharge scuba diver cylinders (3000psi) . This is the only part I couldn't make. Brand new these pumps start at about £2000.

The main objection to Paul's scheme is likely to be cost. With persistence, good advice and sufficient cash I'm sure he can make it work. What I doubt very much is that he can make oxygen cheaper than he can buy it.

My local hospital is big enough to makes its own oxygen rather than buying it in. The plant needed to make their on-site manufacture of oxygen economic is bigger than my house.

Good luck to Paul, I hanker to liquefy gases too! (Only as a challenge, I don't use gas apart from a bit of soldering and brazing)

Dave

Edited By SillyOldDuffer on 09/10/2016 11:14:48

Very interesting areas I never knew about. But wouldn't oxy-hydrogen be easier?

Instructable mentioned earlier.

Here we go again. After only a few days, I am subjected to yet another insane post by the quite frankly perverted sense of reasoning of some of the individuals that frequent this site.

I struggle like a man put overboard in a force 10 gale to understand what part of my post you see as pessimistic. It was and is intended to be a congratulatory statement of the very highest order. Quite frankly, the original poster has achieved something akin to god like powers in my opinion. As for the liquefaction of gasses using the Joule - Thomson method, I had actually just come here to write about that. One of those ideas you look at and think " why didn't i think of that..."

Please in future read the posts before going off on one. I am really, really sick to the back teeth of this kind of thing from what is admittedly a small minority of people who post here. All you are doing is driving people away.

Stick with it Paul

Invention comes from, perseverance, persperation and the heart.
Formal qualifications may help but it did not stop these men.

**LINK**

Regards

I can vouch for using an oxygen concentrator; I've used a 5 L/min Devilbiss for oxy-propane brazing for years with a lightweight welding torch and propane mixer.. It works fine except when using a large tip at high flows when the oxygen drops off a bit, so make sure you factor this in if you plan to braze hefty components. It costs nothing to run and is a massive saving compared to a hobby cylinder or renting a large one. Molecular sieves are routinely used in science labs for supplying nitrogen and oxygen rather than keep cylinders around. I don't think the oxygen is liquified but rather pressurised in the concentrator - anything which produces liquid oxygen would be extremely dangerous as I can testify after setting fire to a safety screen with it during a science demonstation some years back . . .

Good luck

Hywel

Military aircraft have for many years used OBOGs, on board oxygen generators. While I do not know their details I am sure that liquification ( if such a word exists) of air is not involved. I believe they use some form of "sieve".

Sorry - I have just Googled OBOGS. The company sites I have looked at talk about sieves.

And now to bed.

JA