Average Gas Consumption

What is your average RMV?

  • less than 0.3 cu ft/min, 8.5 l/min

    Votes: 12 1.3%

  • 0.3-0.39 cu ft/min, 8.5-11.2 l/min

    Votes: 108 11.4%

  • 0.4-0.49 cu ft/min, 11.3-14.1 l/min

    Votes: 256 26.9%

  • 0.5-0.59 cu ft/min, 14.2-16.9 l/min

    Votes: 289 30.4%

  • 0.6-0.69 cu ft/min, 17.0-19.7 l/min

    Votes: 142 14.9%

  • 0.7-0.79 cu ft/min, 19.8-22.5 l/min

    Votes: 93 9.8%

  • 0.8-0.89 cu ft/min, 22.6-25.4 l/min

    Votes: 24 2.5%

  • 0.9-0.99 cu ft/min, 25.5-28.2 l/min

    Votes: 10 1.1%

  • greater than or equal to 1.0 cu ft/min, 28.3 l/min

    Votes: 17 1.8%
  • Total voters
    951

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datattack:
I am a newer diver but on good days I can get to around .58 cu ft/min maybe .55? But usually in the .58-.65 range but hoping to get it down to .50-.55 more consistently with more dives under my belt!
Click to expand...
You should be able to get it down. As you gain experience, you should be able to shed some weight from your kit thereby reducing the amount of air you have to add to you BCD. That will get you more streamlined
and reduce your drag in the water. And, you'll get more comfortable int he water. When I first started I was at a higher rate of air consumption than you and I'm consistently below .5 now and have a few times dipped below .4. So keep diving and improving and you'll more than likely get there, too.
 
Just 3 days, another 1,000 views, now more than 84,000. Six more votes in the poll, now 941.

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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.

My wishes for great diving
 
More than 85,000 views and 942 votes in the poll.

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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.

Good diving to all
 
Now, more than 86,000 views and another 5 votes in the poll, for a total of 947

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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.

Great diving
 
it really depends on the kind of dive;
for me:
- double 12l and drysuit; 11.3-14.1; easy dive SAC approx. 12l/min
- double 12l, stage 80cft and drysuit; demanding dive SAC approx 15-16l/min

I voted 11.3-14.1
 
:bday: :hb2:

This thread is nine years old today and is still going strong.

I have been following my own RMV for 15 years now. I have my RMV for 2,014 of 2,045 dives during those years, 98.5%. I already had nearly 450 dives before I started following my RMV. These dives represent a wide variety of recreational and light decompression dives with regard to water temperature, visibility, current... All were with a single back mount cylinder, many solo with a pony, and all were in a wetsuit. My gas consumption has not changed much during this period, a little lower, perhaps with a little less variation. The last 3 years are a bit overrepresented by 2-week trips to Bonaire, where the diving is so easy. It is very clear to me that exertion, being cold, and anxiety are the main determinants of my gas consumption. My highest RMV was 0.63 cu ft/min at Halfway Rock in Cape Ann, MA in 2010. It was a dive in 49-degree water in brisk current. It followed a dive on the Chester Poling where the water was 47 degrees and my RMV was 0.53 cu ft/min. I have 11 dives with an RMV >0.50 cu ft/min. My lowest RMV was 0.26 cu ft/min on a dive in Bonaire. Many of my dives with the lowest gas consumption have been in places I know very well and have easy conditions, like Bonaire or SE Florida. I have only 72 dives with an RMV <0.30 cu ft/min. Though I am 71 years old, I'm hoping to continue my diving for many more years :)

1751546836503.png

mean +/- std dev
 
Kevrumbo:
And here's an exercise on the difference between Volume SAC Rate (also known as RMV) and Pressure SAC Rate, and how to actually use Pressure Sac rate for the cylinder that you are breathing.

Example:
Given a Volume Sac Rate of 22 liters/min*ATA, divide it by the Tank Factor Rating of the Cylinder in use. For an AL80 cylinder with a tank factor rating of 11 liters/bar:

22 liters/min*ATA divided-by 11 liters/bar = 2 bar/min*ATA Pressure Sac Rate

Now instead of a single AL80 with an 11 liters/bar tank factor rating, use a twinset (double AL80's) for a total of 22 liters/bar tank factor rating, and let's see what happens to the Pressure Sac Rate:

22 liters/min*ATA divided-by 22 liters/bar = 1 bar/min*ATA Pressure Sac Rate.

So the point is: your Volume Sac Rate of 22 liters/min is constant across all tank sizes & capacities, but it is your Pressure Sac Rate that will change with the sizes & capacities (i.e. tank rating factors) of the cylinders that you actually use.

______
Below are some example pressure Surface Consumption Rate (SCR) values for a variety of common cylinders with a given arbitrary volume SCR (also known as volume SAC rate or RMV):

Given a arbitrary nominal volume SCR of 22 liters/min per ATA (that's 0.78 cuft/min per ATA in US Imperial Units, a reasonable & achievable volume SCR for most novice divers):

Cylinder Size | Pressure SCR
11L/bar tank (AL80): 2bar/min per ATA;
12L/bar tank (Steel HP100): 1.8bar/min per ATA;
13L/bar tank (AL100): 1.7bar/min per ATA;
15L/bar tank (Steel HP119): 1.5bar/min per ATA;
16L/bar tank (Steel HP130): 1.4bar/min per ATA;
11L Twins (Double AL80's): 1bar/min per ATA;
12L Twins (Double HP100's): 0.9bar/min per ATA;
16L Twins (Double HP130's): 0.7bar/min per ATA.

Given a arbitrary nominal volume SCR of 15 liters/min per ATA (0.53 cuft/min per ATA in US Imperial Units):

11L/bar tank (AL80): 1.4bar/min per ATA;
12L/bar tank (Steel HP100): 1.3bar/min per ATA;
13L/bar tank (AL100): 1.2bar/min per ATA;
15L/bar tank (Steel HP119): 1bar/min per ATA;
16L/bar tank (Steel HP130): 0.9bar/min per ATA;
11L Twins (Double AL80's): 0.7bar/min per ATA;
12L Twins (Double HP100's): 0.6bar/min per ATA;
16L Twins (Double HP130's): 0.5bar/min per ATA.

Given a arbitrary nominal volume SCR of 11 liters/min per ATA (0.39 cuft/min per ATA in US Imperial Units):

11L/bar tank (AL80): 1bar/min per ATA;
12L/bar tank (Steel HP100): 0.9bar/min per ATA;
13L/bar tank (AL100): 0.8bar/min per ATA;
15L/bar tank (Steel HP119): 0.73bar/min per ATA;
16L/bar tank (Steel HP130): 0.68bar/min per ATA;
11L Twins (Double AL80's): 0.5bar/min per ATA;
12L Twins (Double HP100's): 0.45bar/min per ATA;
16L Twins (Double HP130's): 0.3bar/min per ATA.

----
If you know your nominal bar/min consumption rate at depth for the particular cylinder used --you already know by rote what your SPG is going to read after a five or ten minute interval of time. So if I started the dive with a full cylinder at 200bar, and have a depth consumption rate of 8bar/min, I know I will consume 80 bar in ten minutes and the SPG will read 120bar remaining pressure. If I then come up multi-level shallower to a new depth where my consumption rate is 4bar/min, I know in another ten minute interval I'll consume 40bar and the SPG will show 80bar remaining. By normal habit and experience over many dives --you just automatically begin to do this iterative subtraction & SPG tracking process. When you finally reach Min Gas Reserve pressure and confirm it on your SPG, you then start your ending ascent to safety stops & the surface. . . IOW, the SPG is telling you, confirming what you already know and figured in terms of remaining gas pressure.
Click to expand...
**** i am lost again 🤣
 
scubadada:
:bday: :hb2:

This thread is nine years old today and is still going strong.

I have been following my own RMV for 15 years now. I have my RMV for 2,014 of 2,045 dives during those years, 98.5%. I already had nearly 450 dives before I started following my RMV. These dives represent a wide variety of recreational and light decompression dives with regard to water temperature, visibility, current... All were with a single back mount cylinder, many solo with a pony, and all were in a wetsuit. My gas consumption has not changed much during this period, a little lower, perhaps with a little less variation. The last 3 years are a bit overrepresented by 2-week trips to Bonaire, where the diving is so easy. It is very clear to me that exertion, being cold, and anxiety are the main determinants of my gas consumption. My highest RMV was 0.63 cu ft/min at Halfway Rock in Cape Ann, MA. It was a dive in 49-degree water in brisk current. It followed a dive on the Chester Poling where the water was 47 degrees and my RMV was 0.53 cu ft/min. I have 11 dives with an RMV >0.50 cu ft/min. My lowest RMV was 0.26 cu ft/min on a dive in Bonaire. Many of my dives with the lowest gas consumption have been in places I know very well and have easy conditions, like Bonaire or SE Florida. I have only 72 dives with an RMV <0.30 cu ft/min. Though I am 71 years old, I'm hoping to continue my diving for many more years :)

View attachment 907026
mean +/- std dev
Click to expand...

The trend of your consumption over time looks good! You will get to <0.30 in just another couple of years
Mine is moving in the other direction unfortunately ;)
 
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