Posted by AADIVER on August 15, 2001 at 09:04:17:
In Reply to: Re: 3rd time's a charm? posted by Steve on August 15, 2001 at 08:43:09:
Many shops require a Nitrox tank to be drained empty before filling regardless the residual amount of gas remaining in it. They are unaware of formulas for "topping off" tanks with remaining gas from a non-blending system. For instance, here's the formula for 40% in an aluminum 80:
Empty: 730 psi O2, then 21% to 3,000
250 670 " " " " "
500 610 " " " " "
etc....
For each additional250 psi remaining, add 60 psi less of O2 up to residual 2,750 psi, add only 65 psi of O2.
There's a computer program that gives the amounts for other O2 percentages of Nitrox but I don't remember the URL.