CaveSloth
Contributor
What are the formulas for calculating standard / accepted practice turn pressures for 2 divers A & B with starting pressures and volumes of Pa, Pb, Va, Vb in PSI and CF?
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Are you asking about gas matching when two divers have different sized tanks.
The formulas won't help you much unless you know where they're coming from.
If you don't know where the formulas are coming from, don't use them. Because you aren't able to check if they turn out the right answer. And if you know where they're coming from, you shouldn't have to ask.
that’s not entirely true. You have no idea how many cave divers with years of experience I know that have no clue how to gas match.
Some are older cave divers who weren't taught. Some just don't see the point and choose not to gas match. Others were taught the math and just never use it, so have forgotten it (and could care less). I personally can't easily do the math on the fly since I rarely need to (rarely dive unmatched team), so I use my cheat sheet.I hope that's because they took their cave courses back in the stone age. Nowadays, I think gas matching is taught in all the intro-level textbooks. One of the few things about cave diving you actually can learn from a book. Mine didn't have formulas, though, which is what the OP is asking for. Rather, we were taught to go through it in a step-by-step way. But of course there are also cheat sheets, as you point out.