PDA

View Full Version : SAC in MS-Excel



deepstop
01-31-2009, 09:35
I put this together this morning, while I was writing a post on one of last year's dives in my blog. Wordpress doesn't allow MS-Excel attachments so I thought I'd put it here and link to it.
The one thing I do differently to those on the web is to take measurement error into account and calculate a maximum rate in addition to the one that is published in books. On the dive last year I was describing, the consumption in 10 minutes was 250 PSI. I'm guessing that I can trust my gauge to about +/- 25 PSI, so that's a 10% possible error. Errors can also be made in tank capacity (small), timing, and depth. This example uses my Faber 95 doubles that have a working pressure of 2640 PSI.
Use at your own risk and modify or distribute as you see fit. I'm not claiming any rights to this invention.
The spreadsheet handles Imperial measurements only. If you'd like me to do a metric version then please post a comment on my blog (http://deepstop.wordpress.com/2009/01/31/tech-skills-on-the-kinghorn/).
Chris

nrembis
02-04-2009, 17:44
Looks like it works ok to me...

I was certified the NASDS way with a wheel that measures SAC in PSI per minute not CFM....I still have it....I think its an antique, LMAO

in_cavediver
02-04-2009, 20:28
Looks like it works ok to me...

I was certified the NASDS way with a wheel that measures SAC in PSI per minute not CFM....I still have it....I think its an antique, LMAO

There is nothing wrong with it - as long as you know the tank it was calibrated with. The math is same now as it was then. The only advancement is using CFM. CFM is tank independent, psi isn't

deepstop
02-05-2009, 06:55
I originally certified with NASDS as well, in 1982. I still have the wheel as well with its attached slate lying around somewhere, along with my old NASDS tables on a slate. We used 72 cu ft steel tanks back then, with 10% overpressure. The AL80 was just being introduced into our area at the time.

nrembis
02-05-2009, 08:02
I originally certified with NASDS as well, in 1982. I still have the wheel as well with its attached slate lying around somewhere, along with my old NASDS tables on a slate. We used 72 cu ft steel tanks back then, with 10% overpressure. The AL80 was just being introduced into our area at the time.

Here is a photo of mine, I was certified in 1989 while living in Daytona Beach, there used to be a shop down there in South Daytona named "Adventure Diving" owned by Ed and Cathy Shabelski. I was a kid back then, I think I lived there at the shop as much as I did at home.

http://www.cincybidz.com/sac_calc.jpg