I've scrolled through all the topics in here but can't find any info.....however it is late and I am tired, apologies if this has been asked before...
I've ordered, but not yet collected a 3litre scuba tank from Go Dive, how many times would that likely fill my 48ci tank?
Cheers
Rich
Theres a fill calculator linked here:
https://www.scubatoys.com/paintball/scubafills2.asp
However the minimum scuba size is an 80. (Which ought to be about 11 litres)
So that’s not going to give you your answer
But it will illustrate that ‘number of fills’ isn’t an exact science, what matters is preservation of the scuba pressure for as long as possible to enable usable fills
In the calculator select ‘aluminium 80 @ 3000psi’ and ‘47ci
Then run each of the 4 options of refilling when at 0, 400, 750 and 1000psi
Only take the results of column one
(the other two columns are to demonstrate using multiple scuba cylinders and cascade filling in stages)
Every time you fill the two cylinders attempt to equalise, but you should stop as soon as possible
Assuming both your scuba and playing cylinders are 3000psi cylinders, if you have an empty playing cylinder and fill to the maximum then you won’t have a 3000psi fill:
You begin with 4 litres at 3000psi plus approx 1/2 litre at 0psi. You then share out that 4litres into 4.5 litres which is a larger capacity and a slightly lower pressure.
Therefore you achieve zero fills of 3000psi (but the reduction is negligible and the gauge looks like it’s on 3000psi
Let’s pretend it became 100psi less over the extra 1/2 litre (first fill = 2900psi
You go al Rambo and suddenly find yourself at 0psi
Take the scuba’s 2900, drop by 100psi and your second fill is 2800psi
You have had zero 3000psi fills, but manage to get 10 fills in excess of 2000psi
The first trick is to never let them equalise, only draw off as little as possible that you could get away with:
For example fill the playing cylinder to no more than 2500psi, the scuba remains over 2500 for much longer so you manage to get multiple 2500 fills before the source scuba drops that low
The second trick is to always top up as soon as possible. This way you are not taking out 0.5l of 2500psi. What you are ideally doing is topping up a few hundred psi at a time
If you can remember mathematics then you might manage to reverse engineer the calculator and make it work for your 4 litre scuba
Because it starts with an 11litre scuba there’s more capacity to maintain the pressure as it is drawing to a relatively smaller playing cylinder (22 times)
In your case the scuba is about 8 times the capacity of your playing cylinder.Not a big drama as it’s pressure you’re after, but the bigger the difference in capacity the more to go around
