Something does add up in my equation?

[Ulfhedinn]

Help me get me head around this arthritic. Something doesn't seem correct.

If my scr is .75 and Im at 4 ata then my DCR is 3 correct? If im using one AL 80 my tank factor is 2.5 so I would be using 120 psi a min at depth? correct?

If I dive with double 80's would my psi/min at depth be 60?

If I'm diving side mount double 80's vs back-mount double 80's is the psi 60 either way if thats the correct psi? Since from what I understand in side mount you dont run cylinders redundant.

This is a two part question. Once I get this worked out Im will add the 2nd part of the equation.

 

[fdog]

Help me get me head around this arthritic. Something doesn't seem correct.

If my [-]scr[/-] RMV is .75 and Im at 4 ata then my DCR is 3 correct? If im using one AL 80 my tank factor is 2.5 so I would be using 120 psi a min at depth? correct?

If I dive with double 80's would my psi/min at depth be 60?

If I'm diving side mount double 80's vs back-mount double 80's is the psi 60 either way if thats the correct psi? Since from what I understand in side mount you dont run cylinders redundant.

This is a two part question. Once I get this worked out Im will add the 2nd part of the equation.

Yes...made a small change for you though.

Can't help you on the sidemount part since I don't dive that way (but it would be 120 psi/minute as you breathe from that individual cylinder).


All the best, James

 

[Jim Lapenta]

Your rate of useage doesn't change. You still use the same VOLUME of gas. You just have double the supply. Figure the useage using volume (cu ft) rather than pressure. Much easier to do.

 

[fdog]

As an aside, I plan with CFM.

Then it's translated to PSI. These are the numbers that go into the water.

Once underwater, I do all my mental math in PSI.


All the best, James

 

[Kevrumbo]

Help me get me head around this arthritic. Something doesn't seem correct.

If my scr is .75 and Im at 4 ata then my DCR is 3 correct? If im using one AL 80 my tank factor is 2.5 so I would be using 120 psi a min at depth? correct?

If I dive with double 80's would my psi/min at depth be 60?

If I'm diving side mount double 80's vs back-mount double 80's is the psi 60 either way if thats the correct psi? Since from what I understand in side mount you dont run cylinders redundant.

This is a two part question. Once I get this worked out Im will add the 2nd part of the equation.

120psi/min in SM as fdog posted above for breathing each independent tank by itself (unless you're using a UTD SM manifolded distribution block with an Isolator Valve, then you would use 60psi/min similar to conventional BM, with both tanks open).

I'm gonna ask y'all a question: which is an easier number to work with, 120psi/min pressure DCR on a psi SPG or 8bar/min pressure DCR on a bar SPG? And in ten minutes at 4ATA depth (100'/30m), you will consume 1200psi, down from a full tank at 3000psi; same as 80bar down from a full tank at 200bar --but which is the easier arithmetic/faster subtraction calculation to figure out your remaining pressure in the AL80 (11L/bar) tank?

Get away from cumbersome US Imperial Units --Go with the Metric System for Scuba. . . !

Diving Metric: Benefits of bar and meters

 

[TSandM]

(unless you're using a UTD SM manifolded distribution block with an Isolator Valve, then you would use 60psi/min similar to conventional BM, with both tanks open)

I thought that, when you were using the UTD distribution block, you had to keep one tank turned off, to make up for IP differences on the first stages?

 

[Ulfhedinn]

I thought that, when you were using the UTD distribution block, you had to keep one tank turned off, to make up for IP differences on the first stages?

I think he was talking about UTD new setup which is this Z-Isolatable Manifold but that still may be the case anyways?

Anyone diving it that can give us a heads up?

 

[Kevrumbo]

Check the IP's of your 1st Stages and match them as best as you can. . .

I dove SM doubles with the original UTD distribution block and breathing only from one AL80/11L tank for the entire dive on a recreational profile (i.e. the other AL80/11L tank was just a "big pony bottle"), and the dynamic instability of one very floaty & the other heavy tank took little to get used to --but wasn't any worse than diving conventional BM with a couple of empty stage/deco bottles clipped to the left side.