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Gas Blending Math (He and Nitrox)

Discussion in 'Technical Diving Specialties' started by Raywerner, Aug 29, 2003.

  1. Raywerner

    Raywerner Angel Fish

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    Thanks to the wonderful information Ihave gleaned from posts on this board, and in Vance Harlow's super Oxygen Hacker's Companion, I have built a continuous mixer (knew I could find a use for that OxySpy) to use with my Max-Air 35. Now, the question I have is where can I find the math that would allow me to blend tri-mix using pp blending of He, and topping it off with Nitrox?

    Thanks!
     
  2. Stone

    Stone Solo Diver

    # of Dives:
    Location: We live in Valparaiso, FL and dive out of Destin,
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    Since you are already using continuous mixing for Nitrox, consider continuous mixing for Trimix.

    Uncle Pug and Omar can help.

    In the mean time, try a search using some of the key words in this thread to find some good information and pictures of some nice mixing stations.

    Good Luck!
     
  3. Uncle Pug

    Uncle Pug Swims with Orca ScubaBoard Supporter

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    Ray Continuous Blending trimix efficiently would take a helium analyzer. Expensive but it sure makes topping up partially full tanks easy.

    Doing what you propose is not difficult. GUE standard gases can be PP blended using EAN32 for topping.

    However... if the math escapes you I am wondering if you have taken a blending course and/or a trimix course?

    Still there are several free mix programs on the web that will do the figuring for you... but you really need to have a good understanding of gas blending anyway IMO.
     
  4. Scuba_Vixen

    Scuba_Vixen Solo Diver

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    if the math escapes you I am wondering if you have taken a blending course and/or a trimix course.....


    Tripped the same trigger with me .....
    I know by the time I got to blending for myself, what part of my brain the dive computer hadn't rotted, was pretty well smoked from crunching numbers learning mix.

    I found my TDI blender course made me do all the math with just a calculator and the formulas. When I did the DSAT course, they just give you a program on a CD for the PC. (You'd be SOL if the PC went down and you had tanks to fill)... Unfortunately, both fail to account for real gas factors (z factors), so if you don't have one of the good excel programs to use to make some adjustments with, neither will get you spot on consistantly.

    Ray, by the time you're really ready to do some blending, you'll be giving the "where to find the math" info to the next guy, lol


    Darlene
     
  5. Raywerner

    Raywerner Angel Fish

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    Uncle Pug and Darlene,

    I am in the "just playing with it" stage, and I will be taking the blending course this winter. I did follow Pug's advise and build in the ability to do continuous Tri-mix blending when I constructed the mixer, but I am just trying to gain an understanding of the process before I plop down the $90 per bottle of He that my gas supplier wants. I am fortunate, though, in that I do have an OxyCheq He analizer so I will be ready when the time comes to do the blending.

    That's kinda why the question. Doing Nitrox is simple enough, adding the He is a new thing to me and I am interested in learning as much as I can before I take the course. (Old brain cells need a leg up, you know.)

    Ray
     
  6. Uncle Pug

    Uncle Pug Swims with Orca ScubaBoard Supporter

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    Check out the Atomox website.
     
  7. blacknet

    blacknet Loggerhead Turtle

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  8. Scuba_Vixen

    Scuba_Vixen Solo Diver

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    or is it still just based on ideal gas law equations. Would be nice to see both, so you can tweak in between if you need...
     
  9. blacknet

    blacknet Loggerhead Turtle

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    Hello,

    that's in the works and the palm version does account for He compression by adding 5%. To my understanding O2 compression is very minimal.

    Ed
     
  10. Scuba_Vixen

    Scuba_Vixen Solo Diver

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    Actually, the Z-factor for O2 is less than 1, so you'll add a bit less than the ideal equation gives, same for the top off with air., The He is about 1.06 (these change relative to pressure, but those are approx at 3000)

    It all translates to about +60# He and -8# of O2 and -50# air on a mix of 15/55 at 3200# .... The usual add 5% rule of thumb comes pretty close

    Looking forward to the final product....

    Darlene
     

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