DAC -> SAC?

[Swedinsidemount]

Hi all!!! I recently handed over my tank(s) to my LDS to install a new manifold for a doubles setup and haven't tested my SAC in a while ( and can't now cause i don't have tanks) and was wondering if you could calculate SAC from your Dive Air Consumption (DAC, and yes i made that up)thx...

(most recent dive)
DAC was .71 cf/min
it was a very shallow (average 12 ft)
but with decent current and a BT of 67mins

P.S. wouldn't this be nice to have integrated into your computer? a real time DAC could have so many applications for technical/ cave divers!!!

 

[grantctobin]

Hi all!!! I recently handed over my tank(s) to my LDS to install a new manifold for a doubles setup and haven't tested my SAC in a while ( and can't now cause i don't have tanks) and was wondering if you could calculate SAC from your Dive Air Consumption (DAC, and yes i made that up)thx...

(most recent dive)
DAC was .71 cf/min
it was a very shallow (average 12 ft)
but with decent current and a BT of 67mins

P.S. wouldn't this be nice to have integrated into your computer? a real time DAC could have so many applications for technical/ cave divers!!!

This is nigh incomprehensible. Look up SAC vs RMV. I don’t think a real time “DAC” has any relevance in technical and cave diving.

 

[Degenerate]

P.S. wouldn't this be nice to have integrated into your computer? a real time DAC could have so many applications for technical/ cave divers!!!

We already know our SAC since way back when.

 

[Swedinsidemount]

This is nigh incomprehensible. Look up SAC vs RMV. I don’t think a real time “DAC” has any relevance in technical and cave diving.

I think it could be a neat gizmo that could be added to AI computers quite easily...but thanks<TG>

 

[Swedinsidemount]

We already know our SAC since way back when.

Yes but as you become more experienced your SAC could go down... i have nothing to do so I thought I would poke the brains of SBers

 

[kmarks]

I don't understand what you're asking. You made up something and called it DAC, but you didn't explain it well. When you say your DAC was 0.71 cf/min on your 67 min dive, are you saying that over the course of the 67 minute drive you burned 47.57 cf of air? So basically, you've done the calculation of starting PSI minus ending PSI times tank capacity divided by rated tank pressure and then divided that by bottom time?

If I'm understanding what you mean by DAC, then you only need to multiply it by the absolute pressure at your average depth and divide by one atmosphere to get your RMV, or SAC, depending on who you ask.

 

[Swedinsidemount]

I don't understand what you're asking. You made up something and called it DAC, but you didn't explain it well. When you say your DAC was 0.71 cf/min on your 67 min dive, are you saying that over the course of the 67 minute drive you burned 47.57 cf of air? So basically, you've done the calculation of starting PSI minus ending PSI times tank capacity divided by rated tank pressure and then divided that by bottom time?

If I'm understanding what you mean by DAC, then you only need to multiply it by the absolute pressure at your average depth and divide by one atmosphere to get your RMV, or SAC, depending on who you ask.

Your calculation was semi correct, i just wanted to know if it was a viable way of calculating SAC based on dive history...DAC is your dive air consumption per min based on tank pressure, depth, heart rate, etc. sorry abou that...<TG>

 

[tursiops]

How do you know your DAC? You said it was 0.71 cuft/min.
Where did that come from?

 

[DiveClimbRide]

If you have the average depth for a dive, total time, pressure used and tank size then you can calculate your SAC. Simply work out how many cf of gas you used in total then divide by the average pressure (depth/33 +1) and divide again by total time. Now you have your SAC. In my opinion this is the best way to calculate SAC because it includes the descents and ascents and is more accurate for planning dives. As for whatever dac is I have no idea

 

[Swedinsidemount]

How do you know your DAC? You said it was 0.71 cuft/min.
Where did that come from?

Tank capacity, pressure, air used, average depth, BT... heres a random example:
(80 cubic foot x 2000 psi)/3000 psi = 53.3 cubic feet of air used
53.3 cubic feet / 20 minutes = 2.6 cubic feet/minute at 66 feet depth
2.6 cubic feet/min / 3x atmospheric density at 66ft = 0.89 cubic feet/min SAC rate