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[b said:

Quote[/b] (aclivity @ Mar. 19 2004,16:47)]this may sound a bit mad, but based on what Mark Chase recommended (i.e. filling one half of a twinset with a whip) then it must be possible to decant from a full cylinder to a twinset via a buddy emergency cylinder?

so, twin 10's breathed down to 100 bar, spare (full) 15l at 232 bar. The manifold is turned off on the twins at the start .......

assuming the buddy emergency cylinder is empty at the start, decant from the 15l to the little cylinder .......

232 bar @15l = 3480l air divided by volume of 15l plus the buddy cylinder (say, 0.4l) = 226bar.

close the valves and transfer buddy cylinder to one half of twin 10s ......

100 bar in a 10l - 1000l of air, plus 226 bar in the 0.4l buddy cylinder = 90l. 1090l of air in a 10.4l join capacity gives an overall pressure of ...... 104.8 bar.

Start the process over again and keep going. So the problem of what do do during the surface interval is solved. I'm sure I could work out on a spreadsheet how many times it would take to transfer maximum pressure to one side of the twins and what that max pressure would be but I'm not sure I could be bothered.

god, this Friday is going on forever isn't it.

it was a stupid idea, but I worked it out anyway (working on a spreadsheet = gives the impression of being hard at work)

I reckon it would take 60 'cycles' of decanting via the buddy cylinder to get within 5% of the pressure you would get by decanting directly. Upi can keep on going forever (according to my spreadsheet model) but the returns diminish probably beyond what is measurable.

However, it did make me think - doing it a couple of times makes sense:

15l ar 232 bar decanting directly into one half of a twin 10 at 100bar:

15 x 232 = 3480l

10 x 100 = 1000l

total gas volume = 4480l

divide by combined cylinder volume (25) = 179.2

Open manifold at this stage ....

(10 x 179.2) + (10 x 100) = 2792l

divided across 2 cylinders - 139.6 bar in both

close manifold

15 x 179.2 = 2688l

10 x 139.6 = 1396l

total gas volume = 4084l

divide by combined cylinder volume (25) = 163.36

do the decant process 3 times and the pressure in the twinset will be 155 bar. After 3 times the increase drops off dramatically. I can provide my spreadsheet if anyone wants it?