Is this their proprietary wacky formula? is this thing legot? It measures PSI / Minute. Sounds a lot like SAC. Any SSI folks out there that can assist?
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Calculating air consumption SAC / SCR / RMV
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there are some excellent threads in the archives on gas management and diving planning. After all, that is the reason for figuring out what your consumption rate is (whether you call it SAC SRC RMV and figure it in psi/min or cf/min.)
But something else you might what to practice: looking at your depth gauge and SPG every five minutes and getting an *feel* for what you are actually using at different depths and activity levels.
After a while you should be able to guess what your SPG reads before looking at it with great accuracy. This is not a substitute for proper gas planning before the dive but rather a very useful adjunct to a well planned dive.
BTW... this skill can be learned for different size tanks surprisingly easy. I usually dive double or single 104s and yesterday was diving a single LP72... after the first two checks (10 minutes) I was guessing my SPG right on the money for the rest of the dive.
But something else you might what to practice: looking at your depth gauge and SPG every five minutes and getting an *feel* for what you are actually using at different depths and activity levels.
After a while you should be able to guess what your SPG reads before looking at it with great accuracy. This is not a substitute for proper gas planning before the dive but rather a very useful adjunct to a well planned dive.
BTW... this skill can be learned for different size tanks surprisingly easy. I usually dive double or single 104s and yesterday was diving a single LP72... after the first two checks (10 minutes) I was guessing my SPG right on the money for the rest of the dive.
My guess is that SCR is just SAC. It probably stands for "Surface Consumption Rate" or some such thing. SSI might have called it something else so they could maximize confusion and try to make their students think they invented it.... :mean:
The formulas are simple and not proprietary.
R..
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SAC and SCR are the same thing. They give you a general idea on air consumption. Remember, if you're reading an analog guage, you're just guessing at the closest pressure anyway. I don't know if SSI created the terms or not. Lots of agencies out their have their own names for the same things. Kinda like ABT, absolute bottom time, TBT, total bottom time or total dive time..... same song, different verse.
I thought ABT was actual bottom time and that ABT + RNT (residual nitrogen time) equaled TBT (total bottom time) on a repetitive dive table...
Big Bubbles
Registered
Sac rate is your surface air consumption used fordetermining how much gas you need for a certain dive. Rmv is the same thing only called Respiratory min vol. The way to find this is gear up get wet and use your spg and timer. The formula is psi used divided by working pressure times total cylinder cap divided by depth in feet + 33 divided by 33 divided by the dive time will give you this rate.
O-ring,
You are correct and it is not agency specific.
You are correct and it is not agency specific.
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You've got me O-ring.
I stand corrected.
I stand corrected.
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ppilot
Guest
Hello all, I have a question I was hoping someone could help me with. I have a feeling that this question is dumb, but I am fearless. Feel free to have at me.
Anyway...I have this little wizz-wheel thingy that is supposed to calculate your air consumption. You dial in air used, depth and time and it gives you an SAC number. Now, if I understand the math behind this:
SAC = ((Air used psi/time in min) * 33) / (depth + 33)
Now...how does this give me a surface air consumption? I ask because I generally use a smaller tank. If I go on a boat dive where they give me a big tank, if I try to plan a bottom time using my normally calculated air consumption, won't I get a number that is far too low?
It seems to me that SAC is good only for a given tank size. Is there a way to relate it to a different one? Or am I totally missing something?
Thanks much.
Anyway...I have this little wizz-wheel thingy that is supposed to calculate your air consumption. You dial in air used, depth and time and it gives you an SAC number. Now, if I understand the math behind this:
SAC = ((Air used psi/time in min) * 33) / (depth + 33)
Now...how does this give me a surface air consumption? I ask because I generally use a smaller tank. If I go on a boat dive where they give me a big tank, if I try to plan a bottom time using my normally calculated air consumption, won't I get a number that is far too low?
It seems to me that SAC is good only for a given tank size. Is there a way to relate it to a different one? Or am I totally missing something?
Thanks much.
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