Tank or compressor?

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marcella69

marcella69

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Oct 31, 2016
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I have an Omega 75 cu-ft 4,500 psi CF tank. I just bought an Omega 12 cu-ft 4,500 psi CF tank (which I received yesterday) to carry in my backpack to re-fill the bottle on my RAW HMx .357 (130 ft-lbf regulated) rifle (which I will not receive until next month). I also have a 4,500 psi Omega Air Charger that I had been using to charge my 75 cu-ft tank from which I would re-fill the bottle on my FX Impact, which I recently sold. 

My issue is whether I should sell my 75 cu-ft tank and simply use my compressor to charge my 12 cu-ft tank and bottle. I was planning to continue to use my 75 cu-ft tank to re-fill my 12 cu-ft tank; but I noticed that in doing so, I could only get the 12 cu-ft tank to charge to 4,000 psi. Now maybe it's just a matter of the respective gauges not being synchronized or properly calibrated, but I really would obviously like to put as much (safely) air in my 12 cu-ft tank.

I am wondering if anybody out there has encountered this issue and what you decided to do.
 
The air should equalize between the two to a point. Compressed air heating and expanding air cooling throws it off a bit. The temperature has to equalize first before you detach. Also assuming you don't have a check valve inline.
1. If you start with 4500 in the big tank the pressure would drop on it while filling. You will never have 4500 on each.
2. The other thing is when you compress air into the small tank it heats up, and the pressure will indicate higher at first. Your psi will drop when it cools.
3. If you are relying on small gauges for the correct pressure you are in for a wild guess. They are very inaccurate.
 
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Yeah, that's why I'm afraid to fill my gun bottle directly from the compressor. The gauge on the gun is imprecise and likely inaccurate. Plus, it would take only three minutes (if my calculations are correct) to fill the bottle directly, and the gun bottle's max pressure is substantially less than that of the compressor. I'm not confident that I can adequately moderate the pressure without damaging the gun.

I think I'm going to sell my 75 cu-ft tank and fill my 12 cu-ft tank with the compressor, then use the 12 cu-ft-er to fill my gun. The 12 cu-ft-er is rated at the same max pressure as the compressor. Plus, it will take six minutes (again, if my calculations are correct) to fill the 12 cu-ft-er with the compressor. This should give me enough time to regulate the fill and get the full Monte on that fill. 

Want to buy a like-new (only eight months old) Omega 75 cu-ft, 4,500 psi carbon fiber tank (with a trick carrying case: $139.95 retail)? Make me an offer :)


 
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Yeah, I used to use the 75 cu-ft tank when I had my Impact with a spare bottle. I sold my Impact to buy the RAW. The RAW also has swappable bottles, but I had leaking issues due to the frequent swap-outs. So I decided to go with a 12 cu-ft tank to carry in my pack to re-fill my bottle. That way, I can keep the bottle screwed in to the gun all the time to prevent excessive wear on the o-ring. Plus, the tank gives me the equivalent of two spare bottles in the field. So, long story short (too late for that), I no longer need the big 75 cu-ft tank.
 
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Ya think? Maybe you're right. I thought long and hard (huh, huh, he said "long." Yeah, and "hard!") about selling it. I guess it would be a lot more convenient to use the 75 cf tank to fill my gun at home and only use the 12 cf tank in the field. That way, I wouldn't be constantly filling the 12 cf-er. I already listed it in the classifieds, though. I did put a price at the high end and I'm diggin' my heels in, so maybe it won't sell.
 
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"Imold"Day late I just bought a 74cf AV tank and my Armadillo kit should be here today, the reason I got a big tank is so I can tether it to my Bulldog .357 or one of my .25s so I can get some good bench time and not have to worry about refilling....I also have a 90ci tank to take out in the woods with me for refills if needed when hunting.
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Make sure your big tank is regulated OR is only filled to 3K (or whatever the gun your shooting is limited to). I use my regulated 90 cu/in tank for tethering though I do have a regulator to use with my 75 cu/ft tank as well. The 90 cu/in tank is just much easier to use unless it is a long shooting session. I also got a 2 meter hose from Best Fittings in the UK (and E-Bay) so I can tether for fixed location hunting from a blind (Hogs)!

Thurmond
 
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intenseaty22, that's somewhat distressing to me. I was counting on the 12 cf-er to give me two full re-fills on my 480 cc 250 bar bottle in the field (plus a fair amount of partial fills). By the time my RAW comes in to actually see if it does, the 30 day return policy at AOA will have elapsed. As per usual, I have jumped the gun yet again ;-(
 
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