Partial Pressure Blending Trimix

[wedivebc]

I was recently looking for a copy of the blending chart that uses the want/have/need/ boxes for trimix. TDI has a nitrox one in the blending manual but I couldn't find one for trimix.
So I put together this simple spreadsheet and thought I would post it here in case anyone else could find it useful.

 

[Storker]

I have to admit I didn't check your worksheet, but is it based on the ideal gas law, or do you include van der Waals coefficients as well?

 

[northernone]

Thanks for sharing. I'll keep it handy. Clean, simple and does what's needed.

Thanks,
Cameron

 

[wedivebc]

I

I have to admit I didn't check your worksheet, but is it based on the ideal gas law, or do you include van der Waals coefficients as well?

ideal gas law formula. If you do any amount of blending you will find the accuracy is sufficient for the mixes we use. People get wrapped up in multi decimal place accuracy then use analog pressure gauges to mix and dodgy cells to analyze. Really for what we do in diving if the O2 is within 1% and the helium is within 5% it make little different in the outcome of the dive.

 

[Storker]

If you do any amount of blending you will find the accuracy is sufficient for the mixes we use.

Depends on your tank pressure. Over here, 300 bar tanks aren't uncommon, and if you fill to 300 non-ideality is an issue