Help with SAC rates

I know this has been brought up before, and I looked in the search, but didn't find all the info I wanted.

First there was a thread once about how to calc the SAC rate, I'll try finding it again, but if somoene knows exactly where it is, could you reply with the link.

Second, I've been playing with the Demo of the "Internet Dive Log" and part of it calculates SAC rates for you. I'm not sure what all of it is... Most of my dives seem to have a "SAC Rate" of 42-15 (not many above 25) This seems to be the rate based on tank size. in the "statistics" section it averages it out for me and says ~58psi consumed per min SAC Rate (PSI/BAR | MIN) 21.06/0.5617

I assume the 21.06 is the rate figured based on tank size, and the .5617 is the one you guys normally refer to, that is tank independent.

Is this right?

Third. Considering that I have 17dives under my belt, and only 4 of them (the open water dives) I don't have beggining and ending PSI for to figure the SAC Rate. How am I doing? I see that .6-.4 is pretty decent. So I guess I'm not doing bad then? Most of my dives seem to be in the .5-.6 range, with an 2 above .7 (first dives after cert, bellow 60feet) and 1 dive at .42 (just this weekend, which this weekend I did .53,.5,.62,.6,.42,.66, and .53 This weekend involved many different dives, including 94' deep dive, and other dives requiring skills to be done, such as using a lift bag)

So being as I have only 17 Dives I assume I'm doing PRETTY Well is that a good assumption?

Just curious where I'm at and where would be a good rate to be at. I still think my consumption S*CKS and would like to have better bottom times, however I know I'm brand new and it comes with time.

Not much time, but SAC is usually expressed in psi/min at surface and is tank dependant.

RMV is expressed in cu. ft/min at surface and is tank independant. Much more useful information.

You seem to be doing okay, but I gotta run and didn't really look that close

MD

SAC rate is normally taught in psi/min at the surface based on the good old aluminum 80.
RMV (Respiratory Minute Volume) is in liters/minute and is frequently expressed as actual consumption rather than a normalized rate at the surface (regulator tests are often at 37.5 and 75 RMV at 5 atmospheres)
SCR, or Surfce Consumption Rate, is generally expressed in standard CFM at the surface and is the term I prefer - I know it's at the surface and it should be CFM.
Rick

Hmm. I was taught RMV for what you are calling SCR. Hadn't seen that term before. Oh well, rose by any other name.

Surface consumption in cfm is what is important as you can apply to any tank and any depth easily.

MD

Ok so it seems the decimal #'s are the vol/min or CFM. Does that sound right? I found a description of how to calc that number in another thread and checked it against one of the records and it was right (well rounded)

WillAbbott once bubbled...
Ok so it seems the decimal #'s are the vol/min or CFM. Does that sound right? I found a description of how to calc that number in another thread and checked it against one of the records and it was right (well rounded)

Click to expand...

Sounds like. I use an RMV of 0.7 for backgas and 0.4 for deco gas for planning.

Sorry your weekend was less than stellar with the bp. Those OMS harnesses suck. If we can get together at Hoodsport you can use my single rig.

MD