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can anyone please tell how much bigger is a 5000psi 88ci fibre air bottle compare to a 68ci bottle and how many years do they hold? do they need testing? many thanks

88ci is about 30% bigger than 68ci although the Ideal Gas Law doesn't hold for pressures above 200 bar (around 3000 psi) so you will probably get around 20-25% more equivalent volume of air at 4500 psi fill.

The most you'll fill to will be around 4300 psi (300 Bar). If filling yourself from SCUBA/Dive Cylinders (I'm assuming 12L 300 Bar like my own) then you'll get about 4000 psi from first fill with a single cylinder. If you have a two cylinder cascade then you'll get about 4200 psi on first fill.

With a single cyclinder fill system you can expect to drop about 200 psi on each fill, whereas a two cylinder cascade will see about 50 psi drop per fill. You'll get around 10-12 useful fills from a single cylinder and up to 25 from a two cyclinder cascade (I personally use 2000 psi as a measure of a useful fill, getting less than that into the tank is pretty pointless in my opinion)

High Pressure Air tanks for non-diving use (basically without a DIN or A Clamp fitting) have to be tested every 5 years and fibre wrapped bottles have a limited lifespan of (I believe) 15 years. Standard SCUBA/Diving Cylinders with DIN or A Clamp fitting are able to be used for diving so have to be tested every 2.5 years, regardless of what you actually use them for.

I did see that London International Paintball Supplies do a 12L 300 Bar cylinder with integrated fill valve for about £240. This is NOT able to be used for diving so is subject to 5 year tests, rather than 2.5 years. From prices I found when was putting together my own two cylinder cascade system, this is a good price when you consider buying a cylinder AND Fill Station. It's equivalent to finding the best price on a cylinder and Fill Station seperately.

If you want to fill the 4500 psi tanks yourself then you either need a complete system like LiPS do, or get a SCUBA/Dive Cylinder and DIN (NOT A Clamp) Fill Station. LiPS do Fill Stations for around £60 and a 12L 300 Bar cylinder will cost anything up to £275, although I managed to find somewhere reasonably local to me where I bought two new Faber steel cylinders for £175 each.

Finally, most Dive Shops can do a 300 Bar fill nowadays and it will cost about £5 to get a 12L cylinder filled.

hey mick

welcome to the forum, excellent post

whereabouts do you paintball?

Welcome to the forum excellent post loads of info