I believe you made an error. 2400L @ 15L/m => 160 min @ surface, not 360. 
I think you're still missing my point. I said the calculation was easy. You spent a lot of typing to show it is easy (in spite of the error).
But you can do the same thing never using volume units (liters) at all. All you need to do is know your SAC rate in bar/min instead of L/min. For the numbers you cite, it's 1.25 bar/min.
This will be different for different sized tanks, because the pressure/volume conversion is implicit in knowing the SAC. But once you have that number, which you calculate out of the water, you never have to use volume in the calcs again. Just put the SAC in your wetnotes for the several tanks you use. Since I only dive 3 different tanks, I know them by heart and don't have to check.
Now you can do all the calculations in pressure units directly. At your specified 5 ATA the DAC is 5 * 1.25 = 6.25 b/min. So 45 bar gives you about 7 minutes.
See how quick that was?
But my point is, if you do the calculation like this using pressure directly, it is just as easy in psi or bar, the only thing different is the numbers. Conversions from/to volume is not necessary at all, and that is the only place where metric has a real advantage when it comes to the very limited set of calculations needed for diving.
I recently dove with someone in the US who was from Europe. He was diving metric.
It was almost trivial. Once I heard what he was diving, I still did all my calcs in my head in imperial (since that is the units I know my SAC in and such of the top of my head), and when I communicated with him, I converted.
Volume never entered into my calculations. It never has to. I worked in pressure.
He probably did his calcs using volume (as you did). It didn't matter. Our communication to each other was in units of distance and time. For distance I just did the feet->meters conversion in my head to talk to him in meters (since he was comfortable with that) and we were golden.
I've traveled and dove with non-DIR metric divers, same thing. Not a real issue.
Scuba has a very limited set of mathmetics that are needed - really really limited. Except when using volume measurements, however, the mathmatical steps are identical between them. Only the numbers are different.
Give me a gauge readig in bar, and my bar/min SAC numbers (I'll put those in my wetnotes today), and I can dive anywhere in the world, because the conversion is already done in calculating my SAC numbers.
This is getting off base. The original question: Should DIR require the same units worldwide? I argue that it isn't necessary. Work in pressure for the calcs, and the specific system of units don't matter. You could work in horse-equivalent-weight-per-fortnight and it would be just as easy.
Now, about the 'black gear' issue...
I think you're still missing my point. I said the calculation was easy. You spent a lot of typing to show it is easy (in spite of the error).
But you can do the same thing never using volume units (liters) at all. All you need to do is know your SAC rate in bar/min instead of L/min. For the numbers you cite, it's 1.25 bar/min.
This will be different for different sized tanks, because the pressure/volume conversion is implicit in knowing the SAC. But once you have that number, which you calculate out of the water, you never have to use volume in the calcs again. Just put the SAC in your wetnotes for the several tanks you use. Since I only dive 3 different tanks, I know them by heart and don't have to check.
Now you can do all the calculations in pressure units directly. At your specified 5 ATA the DAC is 5 * 1.25 = 6.25 b/min. So 45 bar gives you about 7 minutes.
See how quick that was?
But my point is, if you do the calculation like this using pressure directly, it is just as easy in psi or bar, the only thing different is the numbers. Conversions from/to volume is not necessary at all, and that is the only place where metric has a real advantage when it comes to the very limited set of calculations needed for diving.
I recently dove with someone in the US who was from Europe. He was diving metric.
It was almost trivial. Once I heard what he was diving, I still did all my calcs in my head in imperial (since that is the units I know my SAC in and such of the top of my head), and when I communicated with him, I converted.
Volume never entered into my calculations. It never has to. I worked in pressure.
He probably did his calcs using volume (as you did). It didn't matter. Our communication to each other was in units of distance and time. For distance I just did the feet->meters conversion in my head to talk to him in meters (since he was comfortable with that) and we were golden.
I've traveled and dove with non-DIR metric divers, same thing. Not a real issue.
Scuba has a very limited set of mathmetics that are needed - really really limited. Except when using volume measurements, however, the mathmatical steps are identical between them. Only the numbers are different.
Give me a gauge readig in bar, and my bar/min SAC numbers (I'll put those in my wetnotes today), and I can dive anywhere in the world, because the conversion is already done in calculating my SAC numbers.
This is getting off base. The original question: Should DIR require the same units worldwide? I argue that it isn't necessary. Work in pressure for the calcs, and the specific system of units don't matter. You could work in horse-equivalent-weight-per-fortnight and it would be just as easy.
Now, about the 'black gear' issue...
