CCR SAC or usage

Discussions about Diving Log 6.0 - questions and hints
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Petrus
Posts: 23
Joined: Sun Jul 25, 2010 09:09

CCR SAC or usage

Post by Petrus »

Hi Sven,

an other "feature" request...

I am moving to the dark side... and are playing with a Poseidon Mkvii rebreather,
As stated in a previous forum post, SAC is not calculated for those evil machines :twisted: .

However I know the pressure for both the 02 and dill are present in the mkvii logs and It whould be nice to see to have a 02 and dill "sac" or consumption rate...
Given o2 is important as it indicates the life of the scrubber being able to calculate what your average 02 consumption per minute is... It among things allows me to calculate if it is safe enough to continue on the current scrubber..

If it makes no sense or its not happening for any other reason... don't worry it is still the best dive log program in the universe.... :D

Pieter
divinglog
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Re: CCR SAC or usage

Post by divinglog »

Hi Pieter

I'm just hiding (set to zero) the SAC rate for CCR dives, because I thought it makes not much sense to display the SAC rate for the diluent gas. I'm not a CCR diver, so maybe I was wrong and it makes sense, but it would have much in common with the SAC rate for OC dives. If you say it could be useful I can activate that.

Sven
Petrus
Posts: 23
Joined: Sun Jul 25, 2010 09:09

Re: CCR SAC or usage

Post by Petrus »

Hi Sven,


I agree with you that dill sac is not usefull for me and likely for other divers as well...
but 02 may be a different issue as it is related to scrubber usage !

Let me try to draw the use case, that way you may be able to decide if it is worth and possible at all:

I'm currently using a cannister of scrubber, that is valid for 405 litre of o2, or 135 bar of the standard 3 liter bottle that comes default with the rebreather.

Oficially your supposed to fill the 02 bottle with max 135 bar, but as you can guess that is a hassle so we top it up to the be around 200 bar.

So now (on a piece of papre stored in the scrubber storage kit ) I track both dive time and bar consumed, and basicly calculate my 02 consumption per time unit. So that I know that when I'm close to 405 liter consumed, I know what the max dive time I can make... or if I need to change the scrubber cannister for the dive I wish to make.

So why whould I like to see 02 consumption in dive log?

Track 02 usage over dives to be able to predict dives I can still make on my scrubber.
See acurate 02 usage and have a nice way of tracking changes if they happen.
Track 02/per minute consistent even if I change the size of the 02 Bottle.


I am currently using nothing more then (bar * size)/ time

And to make it even perfect,if you could add a fresh scrubber flag for a dive, so you could even calculate total 02 consumption for a scrubber filling.

I know this whoudl work for me, ans assume it works for other ccr divers as well.
We always whould keep track seperatly as weel, but it whould be great for referencing and planning

thanks,

Pieter
divinglog
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Re: CCR SAC or usage

Post by divinglog »

Hi Pieter

If I understand you correctly, this is not the SAC like it is calculated for OC dives, because you do not take the average depth into account. If you take a look at this blog post where I explain how Diving Log calculates the SAC, you can see a different formula.

I don't think that the current SAC calculation works for your scenario, because the O2 tank is not assigned to a part of the dive profile (usually the diluent is assigned to the profile). So Diving Log cannot calculate the average depth for the O2 tank (I know it's the same as the diluent, but Diving Log does not know that). It's just an O2 tank for the application which is not used in any part of the profile.

I could however add the calculation "(bar * size) / time" into the tank management window for CCR tanks. I would not like to add this into the logbook window to avoid confusion, because it is not the same as the SAC which is usually displayed there.
Petrus
Posts: 23
Joined: Sun Jul 25, 2010 09:09

Re: CCR SAC or usage

Post by Petrus »

sound as a perfect solution to me!

Pieter
stfr
Posts: 2
Joined: Mon Jul 25, 2011 02:15

Re: CCR SAC or usage

Post by stfr »

I hope I don’t hijack the post with this request, but I thought my suggestions would be another solution for this problem.
I personally track the time I have on my scrubber and replace it according to the manufacture recommendations and dive conditions. A field which would allow me to enter the date/time I have packed the scrubber and a second which just adds all dive times (CCR) since then, including the displayed dive would be helpful.

Best – Stephan
divinglog
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Re: CCR SAC or usage

Post by divinglog »

Hi Stephan

Sounds also reasonable. I'll see what makes most sense and maybe we get some more opinions from other CCR users. It will take anyways some time until I can add this, because right now I'm working on the Windows Phone version and there are also some other things which have to be added to the desktop version first.

Kind regards,
Sven
Petrus
Posts: 23
Joined: Sun Jul 25, 2010 09:09

Re: CCR SAC or usage

Post by Petrus »

a scrubber time field whould be ok too. You could argue it is part of the Tank dialog box as it is relevant to consumption.
However any field location whould do.

Thanks
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