Continuous Blending with homemade stik

diverb · May 16, 2002

I want to build a nitrox stik to do continuous blending for Nitrox up to 40%.

From the oxygen hackers companion.

My question relates to what calculations I need to do to determine the best diameter for the PVC body

Also, the length of the mixing chamber.

It makes sense that the diameter of the chamber is sized based on the flow rate. Too small, and you are restricting air flow to the compressor, too big, and you will adversely effect the mixing.

In terms of length, I wouls assume flow rate, and diameter come into play in this calculation. Too short, and you don't get a good homogenous mixture.

Any advice would be appreciated?

MikeFerrara · May 16, 2002

I think UnclePug has a home made stick. If he doesn't come on here you might PM him.

omar · May 16, 2002

So you think you can build one for less than $75.00 ??

An inline mixer with threaded ends which allow easy hook up to almost any thing that will work for this use can be had for $75.00 (new).

If you are just interested in the challange than there are a number of wonderful resources available at the local library on flow.

Air is like water, just a different viscosity so you will need to know viscosity, specific gravity, and determine if you have laminar or turbulent flow in the chamber (Reynolds number or similar ).

omar

MikeFerrara · May 16, 2002

omar,
What is there for $75 that will work? I have seen the stick but it goes for about $2000.

omar · May 16, 2002

A static inline mixer, 11inches in length, 0.473 I.D. with 3/8 NPT threaded ends made out of clear schedule 40 PVC. The next size up is $95 (12 x 0.602, ½ NPT)

You will need to get fittings/adapters for the ends, a filter for the intake, and a regulator for the supply gas and hose.

I would get a PVC adapter that goes from the pipe end to the size for a intake filter housing, drill a hole in it and put a barb tube fitting in it for the O2 supply, put the filter & housing on, get a threaded adapter to hose fitting to run to the compressor intake. I would then look on e-bay to get a good oxygen regulator with a variable area flow meter on it and you are done.

You can do all of this for about $150.00

omar

o2diver · May 17, 2002

Omar, where can I pick up these tubes you talk about?? Please shed some light as I'm very interested.
Thanks
O2diver

diverb · May 17, 2002

I am curious to hear more about this too. Do you have a resource that you could direct me too? Part Numbers, anything.

I am an electrical engineer, and while I find it intriguing, I don't have any desire to get into process engineering any more than absolutely necessary. Laminar flow, and sizing pipes, doesn't make my blood pump.

Thanks for the help.

omar · May 17, 2002

These were designed for fluids but as I said before the only difference is the viscosity of the medium. These will work a hell of a lot better than a number of "scuba" blending setups. A case in point is the IANTD blender which is a joke. I was looking for something like this when I setup my blending system. I didn't find them until after (of course). I have put together one of these with 2 of the smaller tubes, a Max air 35 filter/housing, the adapters from the local Home Depot, for a buddy. It works great.

http://www.coleparmer.com/catalog/product_view.asp?pfx=U&sku=0466987&cat=1&sel=0466987

http://www.coleparmer.com/catalog/product_view.asp?pfx=U&sku=0466991&cat=1&sel=0466991

omar

the url is all one line

DNAXdiver · May 18, 2002

The Nitrox Stick uses a SS ribbon vortex mixer similar to the ones mentioned in this thread. Can't rememeber the make or model no. but if you look up the Nitrox Stick patent it tells! But the element alone costs $200-400.

Why not just build the oxygen hackers version? I know of a couple of them in operation, and they seem to work fine. Best thing, since it only costs $10 or so to build if you don't like the way it works you aren't out much.

Originally posted by diverb
I want to build a nitrox stik to do continuous blending for Nitrox up to 40%.

From the oxygen hackers companion.

My question relates to what calculations I need to do to determine the best diameter for the PVC body

Also, the length of the mixing chamber.

DNAXdiver · May 18, 2002

Found it.

Patent no. 05992464

or try this URL if your browser can fit it all:

http://patimg2.uspto.gov/.piw?docid...=6%26f=G%26l=50%26d=ft00%26S1=nitrox%26OS=nit

Continuous Blending with homemade stik

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