Gas Blending

Blend up to any target O2/He mix using pure oxygen, pure helium and a bank/topping gas. Leave the starting gas at 0 psi for a fresh/empty cylinder, or fill it in to blend up from whatever's already in the tank.

This target mix can't be blended from this starting gas using O2 + He + the selected topping gas alone.

You have a known mix in the tank and you're topping it off with a known gas (air, or another known mix/bank). This calculates the resulting mix - nothing to solve for, just a weighted average.

You have the wrong mix in the tank. This calculates the pressure to vent down to before topping back up with a correction gas, so you land on the target mix with minimal wasted gas. Not every target is reachable with a single correction gas - if it isn't, try a different correction gas or use Blend Trimix/Nitrox instead.

This target isn't reachable by bleeding down and topping with this correction gas alone - try a different correction gas, or use Blend Trimix/Nitrox instead.