Average Gas Consumption

[scubadada]

A quick thousand views, now more than 74,000. Seven more votes in the poll, now 872

The median, mode, and weighted average remain 0.5-0.59 cu ft/min or 14.2-16.9 l/min.

If you have not voted in the poll, please consider doing so. If your average RMV has changed, please change your vote.

Go diving

 

[scubadada]

More than 75,000 views and 878 votes in the poll

The median, mode, and weighted average remain 0.5-0.59 cu ft/min or 14.2-16.9 l/min.

If you have not voted in the poll, please consider doing so. If your average RMV has changed, please change your vote.

The best of diving to everyone

 

[Blackcrusader]

More than 75,000 views and 878 votes in the poll The median, mode, and weighted average remain 0.5-0.59 cu ft/min or 14.2-16.9 l/min. If you have not voted in the poll, please consider doing so. If your average RMV has changed, please change your vote.

The best of diving to everyone

I did a dive a few dives today with an American technical diver on vacation. He has no camera rig and dang, he was in great horizontal trim and barely moving the last dive. Me I have my camera rig and was taking a couple of videos and some photos and moving around to get my filming done. I thought I wasn't doing too well on gas consumption.

Something definitely not right in my head...... Sac rate 8.03 I just felt a bit off
AL 80 200 bar start 90 bar end. Really slow dive.

Thing is Shearwater cloud shows it as bar/min 0.73 The tec diver was at 1.00 as he uses a transmitter so checked after the dive. So is the new standard bar/min?

 

[rsingler]

So is the new standard bar/min?

No. Whether it's pressure in bar, or pressure in psi, SAC is tank-dependent. In order to compare your consumption with your American technical buddy, you have to account for your potentially differing tank sizes. If you two each had the same tanks, yes - you could compare your differing consumption via bar/min. But then you couldn't compare with the other 877 divers in @scubadada 's poll.
RMV remains the standard, whether it's l/m or CFM.

 

[therookie]

No. Whether it's pressure in bar, or pressure in psi, SAC is tank-dependent. In order to compare your consumption with your American technical buddy, you have to account for your potentially differing tank sizes. If you two each had the same tanks, yes - you could compare your differing consumption via bar/min. But then you couldn't compare with the other 877 divers in @scubadada 's poll.
RMV remains the standard, whether it's l/m or CFM.

What gets so confusing for newer divers like me is that it seems SAC and RMV are often used interchangeably, when they really are technically not the same thing...

When I first saw that post from @Blackcrusader I thought "How can it be 8.03 if it was 0.73 bar/min? Isn't the conversion rate from bar to psi ~14.5?"

I had to look at that screenshot very carefully to understand that the 0.73 is bar/min and the 8.03 is litres/min. And that put my sometimes-OCD-ish brain at ease again...

 

[scubadada]

No. Whether it's pressure in bar, or pressure in psi, SAC is tank-dependent. In order to compare your consumption with your American technical buddy, you have to account for your potentially differing tank sizes. If you two each had the same tanks, yes - you could compare your differing consumption via bar/min. But then you couldn't compare with the other 877 divers in @scubadada 's poll.
RMV remains the standard, whether it's l/m or CFM.

Yes, there has always been confusion regarding the use of SAC and RMV. I define SAC as pressure/time, either psi or bar/min. As @singler points out, this is cylinder dependent. I define RMV as volume/time, either cu ft or liters/min. This is cylinder independent. My Average Gas Consumption poll, started over 8 1/2 years ago, uses RMV, volume/time.

I started a thread a little over 2 years ago addressing the definitions of SAC and RMV. Less than half defined SAC as pressure/time and defined it as volume/time. Nearly everyone defined RMV as volume/time. I doubt this confusion will ever be resolved. As long as one gives the units, psi or bar/min or cu ft or liters/min, the meaning should be clear.

There, I'm sure that is clear to everyone

Question Thread 'Definitions for SAC and RMV?'

Feb 5, 2023

This topic comes up over and over. Let's see what you think. Please vote once for SAC and once for RMV or vote for #5 and elaborate in your post or #6 if you don't know what this is all about.

• scubadada

 

[kingsisyphus]

I just added mine - current average is a bit over 15 l/min (SAC = ~1.2 bar/min, AL80). Seemed higher than I recalled - checked old data, was more like 11 l/min (SAC = ~1 bar/min) - only thing that has changed is i quit smoking.

Do I need to start smoking again to lower my air consumption? /s

 

[grantmac]

Changed my vote. Now averaging 11-12l/min in drysuit and doubles.

 

[Blackcrusader]

No. Whether it's pressure in bar, or pressure in psi, SAC is tank-dependent. In order to compare your consumption with your American technical buddy, you have to account for your potentially differing tank sizes. If you two each had the same tanks, yes - you could compare your differing consumption via bar/min. But then you couldn't compare with the other 877 divers in @scubadada 's poll.
RMV remains the standard, whether it's l/m or CFM.

Yes I understand for different tank sizes reading would be different. We all using AL80's.
Last few days I have not been bringing my camera rig cause I broke my camera tray. This does change the way I dive a bit. Also switched to nitrox 32% and just sort of doing a near square profile dive. So my lowest NDL of 2 mins was at 50 mins into the dive. Then I slowly ascended from 18m depth got to safety stop level at 56 mins back at surface at 62 mins. Nice warm water 27C and a slow current to drift with.

 

[Dan]

0.61 bar/min on AL 80, that’s pretty impressive!