Gas topping off spreadsheet or website?

[Griffo]

There's a whole bunch of pre-made charts here -> UW Explorers Dot Net » Downloads - UW Explorers Dot Net

 

[rx7diver]

I've never had a good mind for memorizing formulae. So for this type of thing I always return to first principles:

FO2 in final mix

= (FO2 in 1st gas)(proportion of 1st gas) + (FO2 in 2nd gas)(proportion of 2nd gas)

= 0.32 x (2,200 / 3,400) + 0.21 x [(3,400-2,200) / 3,400]

= answer


(Of course, this is the same solution given above by eponym.)

 

[HenrikBP]

Mix blender for iphone (and I think Android) is a nice app for exactly that purpose:

App Store - Mix Blender

 

[Rhone Man]

I wrote a spreadsheet to do this for me (for nitrox and trimix). Happy to e-mail it to you if you PM me your e-mail address.

 

[Hepcat62]

PADI (ahem!) actually do a nice little bit of software, for windows, called the Gas Mix Calculator.

Allows you to plan initial fills, or top-offs, for air, nitrox and trimix. Metric and/or Imperial. Gives MOD (1.4/1.6) whilst you're at it.

It normally comes with the 'Gas Blender' course manual.

I never cared much for that program - mostly because it's really geared for partial-pressure blending with 100% O2. I wrote my own gas blending program that intelligently supports arbitrary nitrox mixes as fill gasses, along with helium. It made it way easier for my (sadly now defunct) LDS to blend the GUE standard gasses, as well as saving a lot of time with producing the vast majority of trimix blends customers were requesting..

Now that I think about, I should really polish that thing up and release it somewhere. At the time I wrote it (and I haven't looked around much since), it was one of only two programs I was aware of that would automatically provide DIRECTLY usable, human-readable fill directions in one step, even when draining the tank to some lower pressure before filling is required (GUE's Gas Management Program being the other one).



EDIT: Just went and looked at GUE GMP again... Surprisingly, it doesn't actually provide instructions for mixing with banked 32% directly, despite that being a huge benefit of the standard gasses. Man, I really should polish this up!

 

[Ulfhedinn]

I never cared much for that program - mostly because it's really geared for partial-pressure blending with 100% O2. I wrote my own gas blending program that intelligently supports arbitrary nitrox mixes as fill gasses, along with helium. It made it way easier for my (sadly now defunct) LDS to blend the GUE standard gasses, as well as saving a lot of time with producing the vast majority of trimix blends customers were requesting..

Now that I think about, I should really polish that thing up and release it somewhere. At the time I wrote it (and I haven't looked around much since), it was one of only two programs I was aware of that would automatically provide DIRECTLY usable, human-readable fill directions in one step, even when draining the tank to some lower pressure before filling is required (GUE's Gas Management Program being the other one).

View attachment 122852

EDIT: Just went and looked at GUE GMP again... Surprisingly, it doesn't actually provide instructions for mixing with banked 32% directly, despite that being a huge benefit of the standard gasses. Man, I really should polish this up!

View attachment 122853

WOW.. looks nice!

If you need anyone to test it... let me know.