Aqualung Computer Algorithm

[acahir]

Just wondering if anyone here knows the answer to a clarifying question. I was reading through the Aqualung i550C manual, but I'm going to assuming this might relate to any Aqualung computer using Z+.

On p14, the manual says:

The i550C utilizes the Z+ to calculate nitrogen tissue loading. Performance is based on Buhlmannn ZHL-16C algorithm model.

which to me implies it's using a 16 compartment model. Yet in the previous paragraph about the N2 Bar Graph I happened to notice:

The i550C monitors twelve difference nitrogen compartments simultaneously and the N2 Bar Graph displays the one that is in control of your dive at any given time.

So is Z+ a 12 compartment model, or is the i550C just ignoring the 4 slowest half-time compartments because they don't really come into play in rec diving limits?

 

[rongoodman]

It's hard to say because it's a proprietary model, but it's true that the slowest compartments show little build-up, even over the course of a one week or ten day trip with 4-5 dives daily.

 

[Centrals]

Dive Computer Algorithms For Dummies

Let’s look at the theoretical models behind modern dive computer algorithms, the differences between the various options and the ways you can influence the algorithm.

dipndive.com

Z+ is based on 16 compartment but as explained it is a proprietary model so anything is possible.
Could be typing error?

 

[acahir]

Yea, that was my understanding too. Just seems like a very specific typo, so much knowledge hidden in this boards, figured it was worth asking.

 

[dmaziuk]

So is Z+ a 12 compartment model, or is the i550C just ignoring the 4 slowest half-time compartments because they don't really come into play in rec diving limits?

I am not sure what you have to do to get your 10-hour or slower TC to be controlling. (Aside from saturation diving, obviously.) DSAT people had some accumulation in the 8-hour compartment by day 6 of relatively intensive diving, so it may be possible...