Have not seen this done before!

[lermontov]

About any contamination at depth could cause a fatality.

agreed once you start getting deep contamination is magnified

 

[lermontov]

Even though I am nitrox certified I don't use it for a number of reasons. Do you think I really need to analyze every tank I use - rentals from my LDS and unlimited air tanks on Bonaire? One of the reasons I don't use nitrox is that I don't want to be bothered with the calibration, analysis, logging, etc when my dives are between 30 and 60 feet, with average depth 30-40 feet. What about CO. If I've got to check every tank for gas mix and CO I'll probably go back to snorkeling.

i would put a caveat on that - if im diving in the tropics or 3rd world where standards may not be monitored as closely i check my gas or if see a messy shop with tanks all over the place I check my gas. Ive seen some very dubious operational systems - just watching the gas filling and the way people handle themselves will give you a sense to take cautions