Switching from CO2 to air

[Johnmac]

Hello all. Just joined the forum and need some advice about air. I'm afraid I am not good with computers or technology in general, and no doubt this question has been asked and answered many times over, so excuse my ignorance!

My four friends and I have various Tippman and BT markers that were running on CO2, and with the January sales and problems getting CO2 fills and or bottles have switched to Air. We now all have 0.8l 3000psi bottles for our markers. We live in Perthshire, Scotland, and have a local dive centre at Dundee and they have so far filled our 0.8l bottles once each at a cost of £3.50 per bottle, which seemed a bit expensive?? Plus it's a half hour drive there and back to fill.

We were thinking of going with a large diving bottle either new or second hand to save us time and money.

Questions are....

What size of bottle/bar do we need?? 12l? 15l??
How much should we expect to pay for a new or second hand bottle in each size??
How much should we expect to pay for a refill of a 12/15l bottle??
Last but not least, how many fills can you expect from a 12/15l bottle into 0.8l bottles??? And are there any problems or issues with dropping pressure as the dive bottle becomes less full??

Many thanks for any help!

John.

 

[Liam92]

well i happen to be a scuba diver as well which comes in handy you can get a good second hand 12l tank for around £100, and since your not going to be diving with them i wouldnt be too worried about buying second hand, but still a good idea to have them tested when due.

well i'm a fan of the bar scale and 230 bar is a standard 12L fill, which is roughly 3,300 psi, which is a little more than what your air tank runs at. so without any specific calculations you could probably expect around 10+ fills. would double check though since i've never done this myself but that sounds like a reasonable estimate. refills at the dive store i worked at go for a few quid, just like the £3.50 your paying, but we also done "air cards" which allowed for a good discount if your filling your tank regularly.

 

[Tom Allen]

the larger the bottle the more capacity it has at a specific pressure, so go for a 4500psi 15L tank if you can get one, and get it filled to 3000psi.

The reason i say get a 4500psi dive tank is, you will eventually upgrade your playing bottles to 4500psi to get longer playing times, so it would be pointless buying a 3000psi or 3500psi dive tank and having to change it when you upgrade. There are other benefits but i won't go into these at this time.

The reason i say get a 15L dive tank is, you'll get more fills from a 15L than a 12L

A fill for your dive bottle will be roughly the same as your paying for each gun bottle, around £3 - £5

 

[Gee Tee]

I've got a 15L 232bar rig myself, and several of my teamates also own 12L 300bar bottles. We used to 'self fill' a lot more years ago, before most sites had compressors and provided air for free. The team worked the dive bottles in specific order, usually bulk filling from the 232bar tanks and topping up to full 4500psi pressure from the 300 bar. This way we could get fills to a good pressure for as long as possible, but inevitably our rigs still ran low after a full days play.

You will notice a considerable drop off in pressure when bulk filling from a single 232 bar tank. Topping off part empty bottles obviously uses less, but still eats into rigs capacity. I'm not sure how fast it'll happen filling 0.8L bottles (most of mine are 1.1L), but when the pressure drops below 1500 psi you'll struggle to get a useable fill. If you could run to a pair of dive rigs (2 x 232bar or 232bar + 300bar) it'll give you more game time, but considerably more £££ to budget for.

Dive tank fills from my local dive shop cost £4, and re-testing was just under £40 when I had one done last season.

Are there not many sites near you that offer on-site HPA filling facilities?