I've also posted this on another airgun forum in hopes that it reaches the widest possible audience! If I violate any forum rules, please let me know, it's my sole intention to save others some of the frustrations I've had trying to find parts and figure out how to do this myself!
Ok, many of you have probably looked at getting into PCP air rifles and decided that, with the price of a 4500 PSI carbon-fiber tank and a hose assembly it's just not worth it. I'm going to share my experience and hope that others can benefit from it, I ended up saving probably a couple hundred bucks on my tank and fill setup. Parts are still coming in, and my tank is off for a fresh hydro right now, so pictures will have to wait a few days but I wanted to get this out there while it's fresh in my mind.
First off, the carbon-fiber tanks that firefighters use are frequently available online, and they come in 3 pressure ratings that I'm aware of. You do NOT want the 2216 and 3000 PSI tanks if you're filling to 3000 PSI, although they might work if you're filling a lower pressure PCP air rifle such as a Discovery. If you're filling to 3000 PSI (such as I need to in my Sumatra) then a 4500 PSI tank is the way to go. When you go searching online and on eBay for a tank you'll find the keyword "SCBA" (>NOT< SCUBA) to be helpful for finding the firefighter breathing tanks. Also, pay attention to manufacture date. According to the D.O.T. these tanks are supposed to be retired after 15 years, I don't know what the actual failure rate is after that period of time and some paintball shops might not care, but it's probably better to buy a tank with as recent of a manufacture date as possible. I bought a "45 minute" (66 cubic foot) tank for $180 shipped, with over 7 years of life left in it, considering that the price of a new "Airhog" tank is around $700, this is a substantial savings. When shopping for a tank, looking for one that has a fresh hydro test (where they pressurize the tank to see if it's safe), is not a bad idea but can add to the cost of the tank. I made the choice to gamble and get a tank that needed a hydro test.
Your next hurdle, after finding a tank, is to get an assembly to fill your air rifle reservoir from that tank. I wanted to make an assembly that would be pretty convenient to fill and has a pressure gauge, bleed valve, and quick disconnect fitting, especially since I'll be filling my SCBA tank at a paintball shop. Also, I've purchased a "quick fill" for my Sumatra from Pyramid, it will allow me to use a quick-disconnect hose fitting. Some air rifles already come with this kind of fill fitting. Back to the hose assembly. SCBA tanks use a special connection that comes in two pieces, a nipple and a nut, this is important to know! For my fill assembly, working from the tank to the gun, I used these parts. First, you'll want the CGA 347 nut and a nipple, the nipple has a 1/4" male NPT fitting on the end that sticks out, this is a standard dimension. I used a "hand tight" nut, BUT if you plan on leaving your fill assembly attached to your tank, you can shave about $10-15 off that by using one that requires a wrench. Next you want a bleed valve that's rated for the highest pressure that'll be going into the tank, I went with a 6,000 PSI bleed valve. I purchased one that had a female fitting on one end and male fitting on the other. Because I'm going to be hooking in a pressure gauge (rated to 5,000 PSI, glycerin filled) the next fitting is a 1/4" female/female/female "tee", and the pressure gauge will attach to that. Next, because I'm using a "hydraulic test hose" rated for 6,000 PSI as my fill hose, and that has 1/8" male NPT fittings on each end, I'll need a bushing to fit that into the tee, a 1/4" male to 1/8" female NPT bushing. I could have had it made with a 1/4" male fitting and done without the bushing, but I had the hose made up after I mail ordered the other fittings and I had been considering a Ralston Industries micro-bore hose. And finally, attached to the end of that hose, is a 1/8" female NPT x 1/8" foster (AKA paintball) quick disconnect.
Now, the cheapest I could find a similar assembly for online was around $160+ shipping. I saved a few bucks by putting everything together myself. Here's my parts list, but if you shop around (or you're lucky enough to live near a hydraulic shop) you can probably shave a few bucks more off that.
The List:
hand tight CGA-347 nut and nipple -----$34.00
MxF 6000 PSI bleed valve -- --------$23.99
1/4" FNPT Tee ----------------$5.88
1/4" MNPT to 1/8" FNPT Bushing ------- $1.00
female paintball quick disconnect -----$16.75
Total for the parts from this vendor:---$81.62
ALSO I had a 6000 PSI hose with 1/8" ID and 1/8" male NPT fittings on each end made at a local hydraulics shop. 2' long and it was $18.20 with tax.
AND I ordered the 5,000 PSI pressure gauge from another source for $10.63
TOTAL PRICE: $110.45 for a "deluxe" fill assembly using quality fittings.
I have teflon tape on hand, so I don't need to purchase that.
Another thing you can purchase to make life easier are a male-to-male paintball adapter for filling your tank at a paintball shop, this cost me a total of $14.76, it's constructed from two 1/8" male NPT x 1/8" foster male fill nipples (AKA paintball fill nipples) and a 1/8" female NPT x 1/8" female NPT coupler. This will allow you to fill your tank at a paintball shop, the shop I called charges $5/fill. It's cheaper than filling my SCBA tank at the fire equipment shop because the paintball shop doesn't have to make sure that it's "breathing" air I suppose.
Ways you can "economize". If your air rifle(s) use a fill probe and you don't have any desire to convert to a "quick disconnect" fixture, you can save a few bucks by not buying the disconnect fittings and just hooking up your fill probe to the hose. You'll still need a way to fill your tank at the paintball shop, or you can just fill the tank at a fire station or fire equipment supply house. Also, you can fill your air rifle without using a hose, I'm paranoid about knocking mine over while filling and possibly damaging the assembly, so I didn't go that route. If you do go that route, you can save a few bucks by ditching the hose and using a F x F x M tee and the appropriate fitting for the disconnect. You can also ditch the pressure gauge if you trust the gauge on your airgun reservoir, but I find that the gauge on my air rifle isn't extremely accurate. This may seem obvious but don't use the gauge on your tank for filling, it tells you the pressure inside the tank and it will do nothing good for you or your air rifle.
One upgrade that I was very much considering is one of those micro-bore .07" ID hoses that everyone loves. They're made by Ralston Industries and there is a list of distributors online. Retail price is somewhere around $31-32 plus shipping for a 3' hose, but if you go shorter with a custom hose you'll save a few bucks. The hose I'm using is .125" ID and only 2' long, so my air loss isn't going to be that bad.
Another upgrade I'm going to do is make a carrying handle/strap out of leather. I have the leather on hand from about 10 years ago, so we'll see how they turn out and I might post some for sale. ::GRINS::
At any rate, I REALLY hope this posting helps some folks. It's very gratifying to have done this myself, and I figure I saved well over $100 over buying a 2002 66 cubic-foot tank and fill assembly pre-packaged. However, there are some VERY reputable sellers with EXCELLENT customer service if you decide you want a "turn key" fill system, just as there are excellent air gun tuners and stock makers. Sometimes it's just more fun to go it yourself. :-)
As a final note, I found both North Shore Compressors and Aerocon Systems to be good sources for the hard to find CGA-347 nut & nipple assembly and the 6000 PSI bleed valve. Most other parts should be available to you locally, I mail ordered mine because I live outside town and I was ordering those parts at the same time. If you have a unique fill probe or something like that it's not a bad idea to go into a shop and bring your parts in with you. Usually the shops you want are listed under "hydraulic" or "hoses" in your local yellow pages. Also, the Ralston Industries micro-bore hoses are available in custom sizes direct from the manufacturer, they were very helpful in emails.
