Recreationall TRIMIX

[MikeFerrara]

Hey every one. I'm new here but I recognize some names. Interesting thread so I'll throw my couple cents in.

I didn't see any mention of the fact that there are two IANTD rec trimix classes. The first is no deco. The second is Advanced rec trimix and has a max depth of 150, max deco of 15 minutes and a max Fo2 of 50% for deco unless the student has taken the decompression specialist class and then they can use 100%. The Advanced Nitrox is of course ïntro to tech and taught right lays down a solid skill foundation. With the addition of the rec trimix classes we can give students all the tools applicablr for those depths. It does seem like a lot of classes and I'm still thinking about the most efficient and economical way to combine them. If any one has any questions the IANTD standards are on their site. I haven't seen the materieals for the classes yet myself.

helium analyzers...

I just recently had the chance to use one for the first time. Over three days of mixing and analyzing there weren't any surprises. I feel better about not having one now. LOL

Another way to solve the problem of knowing what's in the tank of course is to top with nitrox instead of air. If you know what the nitrox was and that the rest is helium, all you need to do is analyze the O2 to know exactly what you have. I plan to set my fill station up for continuous blending and bank 32%. That makes it easy to mix the mixes that some refer to as standard because all are made by topping with 32%.

Which brings me to my next point. If gasses mix immediately, why are there so many products made to mix them?

I won't try to explain why this is but I can demonstrate it any day for any one who wants to see it. If I mix say 50% and add the O2 through my hyper filter veeerrryyy slowly. When I use my mix controller, which has a flow restrictor and my hyper filter which also has a flow restrictor I can't pump it anyway but slow. I can analyze it and read as low as thirty something percent. I can let the tank sit for a fairly long time and the reading won't have changed much. I can roll that puppy on the ground and it'll jump right up to 50%. The less air I'm topping with and the slower I add it the more pronounced it is.

I asked some one at Purdue about this and the answer was that the geometry of the container had an effect on how the gasses mixed.

I can't explain but it does hapen and I can demonstrate it repeatably.

I don't see it when mixing trimix or lower FO2 nitrox because I'm doing the final topping right off the banks and a slow fill from there is still way faster than off my hyper filter.

Oh, I read where some one mentioned Greg Such. I'd recommend him.

Mike