Continuous Gas Mixer

[kidspot]

I just finished reading the Oxygen hacker's Companion - What a great read. I was reminded of the writing style that has made the "Dummies" books so popular. I had a hard time putting it down.

While I'm a ways away from doing anything he mentioned (still a very new diver, but learning all I can) I was fascinated with the plans for the continuous nitrox mixer plans he has on page 105. I was wondering if instead of using baffles anyone had tried using ping-pong balls or marbles instead to premix the gases before they hit the compressor? I remember seeing an aquarium filter that used them to increase surface area, and thought it would also be a great way to create a lot of turbulance in the chamber.

Anyone try this already (or is this really old news that I failed to find in the archives?)

Just curious at this point is all. But I can easily see myself getting into gas mixing in the future - sounds like it's right down my alley. (maybe I'll start by building the O2 analyzer - looks like a lot of others have found them quite easy to build)

Next I'm trying to decide if I should read the HP Gas booster book or the regulator repair book - Vance Harlow has some great material out there.

Tim

 

[Scuba Cowboy]

Vance is one of those people who has done a great service to the diving public. When I first got into using nitrox, so much of the info was kept secret, treated as if only a dive shop was capable of having anything to do with nitrox. The Oxy Hacker book really debunked all the voodoo black magic notion and started me on the road to discovery. I now do all my own nitrox fills, actually I'm one of the few doing them in my county, none of the shops in my area do them. Don't know about your ping pong ball idea, I do know his plans work, built one and it works great. Send him an e-mail and ask about it, I believe he is very helpful and will give you feedback on any idea.

 

[Uncle Pug]

I've thought about the marbles... at first I thought they would be ideal for a tortured path... but they could also present too much flow resistance. A vacuum gauge fitted between the compressor and blender would tell you how many marbles you could lose and still be a blender.

I only have two baffels in my blender... each with randomly drilled holes.

 

[scubatoys]

You're probably thinking "bio balls" not ping pong balls. That's what we have in our aquarium. They have a lot more surface area in them. Another fast and easy baffle is shower drain covers. Already have your holes, just stagger a few in there - assuming you can find some to fit your diameter of PVC.

 

[Dan Gibson]

If you time is worth anything, then just go to McMaster Carr and look for an inline static Mixer. They only cost about $80 and work very well. Depending when you order and where you are, you will have it the next morning.

Here is mine prior to adding helium upgrade:

http://www.allenhost.com/gallery/album341/aal

btw, I have a great source for a $45 O2 reg/flowmeter. You can also get threaded PVC fittings to make this easier than mine. I have since modified mine and will post the new pics some time soon.

I just finished reading the Oxygen hacker's Companion - What a great read. I was reminded of the writing style that has made the "Dummies" books so popular. I had a hard time putting it down.

While I'm a ways away from doing anything he mentioned (still a very new diver, but learning all I can) I was fascinated with the plans for the continuous nitrox mixer plans he has on page 105. I was wondering if instead of using baffles anyone had tried using ping-pong balls or marbles instead to premix the gases before they hit the compressor? I remember seeing an aquarium filter that used them to increase surface area, and thought it would also be a great way to create a lot of turbulance in the chamber.

Anyone try this already (or is this really old news that I failed to find in the archives?)

Just curious at this point is all. But I can easily see myself getting into gas mixing in the future - sounds like it's right down my alley. (maybe I'll start by building the O2 analyzer - looks like a lot of others have found them quite easy to build)

Next I'm trying to decide if I should read the HP Gas booster book or the regulator repair book - Vance Harlow has some great material out there.

Tim

 

[ScottyK]

Next I'm trying to decide if I should read the HP Gas booster book or the regulator repair book - Vance Harlow has some great material out there.

Tim

They are both great books. I would recommend you read the regulator repair book first. As a new diver, it's more likely that the reg book will provide something practical that you can use. Also, if you are technical enough that blending your own gases doesn't intimidate you, you'll probably find servicing and repairing your own regs a cinch.

 

[kidspot]

They are both great books. I would recommend you read the regulator repair book first

oops - already started the booster book - At this point all of them are information for the sake of information (I just enjoy learning new things like this - fascinating) But you are right the reg repair will come in handy soon enough. And I'm looking forward to applying a lot of this stuff in the next year or two (or maybe sooner).

Tim

 

[Uncle Pug]

The inline static mixer looks like it would cause at least some drag on the incoming gases as it has about the same ID as the intake on the compressor. Is this the case? Have you checked your system with a vacuum gauge with and without the mixer in place?

 

[oxyhacker]

You don't have to even email him!

I'm not crazy about ball baffles since they provide a lot of resistance, and don't necessarily double the flow back on itself as it necessary to assure good mixing. Like a series of baffle plates with holes drilled in them, the gas can still channalize to one degree or another so you have in effect several descrete columns of gas zigzagging through the baffles, but hardly mixing. Actually, I don't think this is that much of a prob in real life, but if better, lower resistance methods that do are available, why not use them?

Re marbles and balls with tiny spikes, the #1 rule of building a mixer is not to put anything in it that is small enough to make it into the compressor, or completely block flow if they get loose. this includes nuts, screen, and any part of a larger object that might possibly break off.

Continuous ribbon mixers like the nitrox stick uses, and M-C sells are great -they have very low resistance, so a really good job of mixing, and come in many sizes, so if you are worried about the resistance you can always just go up a size. However, for the homebuilder, I don't think they offer enough advantage over homemade baffles to be worth the price.

Send him an e-mail and ask about it, I believe he is very helpful and will give you feedback on any idea.

 

[kidspot]

You don't have to even email him!

lol -

Thanks for the info - and thanks for an informative (and fun) read - I'm nearly done with the Booster book (well beyond my skills at this point, but fascinating no less) and eager to get to the reg maintenance book.

Thanks,

Tim