Gas Management With Sidemount

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If you can tell, why have a protocol dependent on time or pressure?
Just switch when needed, look at the spg two or three times an hour to be sure.
Dive, don't calculate.
 
I agree, in sidemount is very rare to drain one of the cilinders no matter if are aluminum or steel, as they will get lighter and you will feel that in your trim especially on the aluminum, manteining equalized is the goal of course watching your spg
 
If you can tell, why have a protocol dependent on time or pressure?
Just switch when needed, look at the spg two or three times an hour to be sure.
Dive, don't calculate.
Dive and LEARN : By rote repetition & practical experience, you will eventually know and predict nominally what your consumption rate will be and when to switch tanks. For a particular time interval like five or ten minutes at depth your SPG's should be confirming what you already know. . .
 
That's for sure, when you get to use the same cilinders size in all your dives, especially if you own them, but traveling you hire what's at the dive site or if you don't own any
 
That's for sure, when you get to use the same cilinders size in all your dives, especially if you own them, but traveling you hire what's at the dive site or if you don't own any
Then you obtain the cylinder tank rating size for hire, and redetermine your new pressure consumption rate --doesn't that make sense?

Here for example:

Given a arbitrary nominal volume Surface Consumption Rate (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 manifolded AL80's): 1bar/min per ATA;
12L Twins (Double manifolded HP100's): 0.9bar/min per ATA;
16L Twins (Double manifolded HP130's): 0.7bar/min per ATA.

Or 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 manifolded 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.

Or 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 manifolded 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.

-->The point is: How difficult is it to monitor gas consumption and tank switching for a particular cylinder size when working with simple base quantities like "1 to 2bar/min per ATA" in Metric?
 
The point is: How difficult is it to monitor gas consumption and tank switching for a particular cylinder size when working with simple base quantities like "1 to 2bar/min per ATA" in Metric?
Show me an spg with 1 or even 5 bar precision, or an ai computer for that matter.
 
Reports, yes, but with a measuring tolerance of a few percent.
Anyway: on an normal spg you can count yourself lucky or have a very good eyesight to guess with more than 5bar tolerance.

I personally dislike air integration enough to not even consider it and it would only enable me to do (probably) more precise but totally unnecessary guesswork.
 
Show me an spg with 1 or even 5 bar precision, or an ai computer for that matter.

No. Precision of the SPG is not the point. . .

Which is the easier math to work with: 1bar/min*ATA or 14.5psi/min*ATA?

For example which is the quicker much easier subtraction to see & figure in your head: 200 bar minus 80 bar equals 120 bar? Or: 3000 psi minus 1080 psi equals 1920 psi? Can you figure this out on the fly how much gas pressure you have consumed and keep a running total of how much remains along with timely nominal tank switches? (In other words, SM Gas management is easier in Metric than in US Imperial units).

For example:

Given a arbitrary nominal volume Surface Consumption Rate (SCR) of 22 liters/min per ATA (that's equivalent to 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 manifolded AL80's): 1bar/min per ATA;
12L Twins (Double manifolded HP100's): 0.9bar/min per ATA;
16L Twins (Double manifolded HP130's): 0.7bar/min per ATA.

Or 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 manifolded 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.

Or 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 manifolded 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.

-->The point is: How difficult is it to monitor gas consumption and tank switching for a particular cylinder size when working with simple base quantities like "1 to 2bar/min per ATA" in Metric?
 
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What system you use is less important than that you have a system, understand its limitations and applicability to the dive profile, and use it consistently.
This is important!

Reading this thread, it's less about gas management and mostly about gas balancing. I'm with Bob. What ever you decide on, make it consistent.

I like to keep tanks within 300 PSI. I breathe one tank down 300 psi or to when it's a multiple of 300 and then start the back and forth. Say my tanks are at 3500. The left gets hit first down to 3300, then I breathe the right to 3000, the left then down to 2700 and so on. I use two Hollis DG03 with transmitters. Each has the transmitter on that side as the primary gas and the one on the other side as the second gas. I use rechargeable batteries in the transmitters and they get changed out every other dive. The only errors that I've encountered have been human induced.
 
https://www.shearwater.com/products/perdix-ai/

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