Okay for you math and or air tank gurus…
The other day I noticed that I got 30 shots from my .257 condor tethered to my 88 cf carbon fiber tank. When I began the tank had 3100 psi in it. When I finished the tank had 2900 psi. That meant 200 psi was used in 30 shots. SOOOOOOO if I start out with 4300 psi in my tank (the max that the dive shop compressor gets me) can I expect to get 210 shots before I am down to 2900 psi? (4300 psi – 2900 psi = 1400 psi divided by 200 psi{air used for 30 shots} = 7 x 30 shots = 210 shots. Just trying to figure out what I’m working with with my “compressor less” set up. Thanks.
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I hope this help you Joe.
http://www.airgunsofarizona.com/Tanks/FillCalc.html.
If you have a small air compressor and you are able to find a cheap used haskel pump with at least 1:30 ratio from Ebay, i could advise you how you can make a poormans HP compressor depends the price you’ll get from the seller.Some of them sells them(Air driven liquid pumps) 200$ if get rid of them.
Your best bet is a SC HYDRAULIC 10-6 series 030 model.This is a good quality non-overpriced American made pump with a high air output capacity which can fill your scuba tank at 5-7 min.They are not as expensive as Haskels but it is hard to find them as a second hand.
Overall you need something similar on this …just must use 10-12bar of pressure for its operation and pump specifications must provide the right ratio to avoid stalling once the pressure gets high.Also you need to build a drip leg to trap the moisture which is simple and easy.
The addition of a bleeding valve is important too.
I built my own tank and my own compressor using two hp pumps and fill it at 700bar.On that pressure i can fill about 40 times my pimped AA up to 380bar to shoot my extra heavy slugs fast and consistent.I know it sounds crazy but this is the way i make things.
You’ll get there eventually, then a compressor….I wish I had the coin for a compressor. Someday, maybe. My buddy sometimes fills my cf tank at the fire dept but he does it too fast and it heats up. When I get home it drops around 2 to 300 psi when it cools. I wish that compressor could put in around 5,000 psi nice and slow.
That would be interesting to me too, as I’m kinda in the same boat, just haven’t dropped for the 4500 tank yet.
Casey,
Five shots on just the rifle tank would get me from 3100 to around 2700 psi. The hard part is no two gauges (at least with my experience) are calibrated the exact same. I would be happy with a ball park. I suppose I could do a controlled test by just shooting my .257 but I also use the tank for two other pcp’s.
I figured the carbon fiber “tank volume” would play a part and I would much rather accept your number than mine 😀
The best thing I can do is next time I get down to 3300 psi in the cf tank (the ideal pressure for my .257) I will tether it and shoot only the .257 and count all my shots down to 2900 psi and then I will know for sure!
I’m not the correct one to answer this specifically, I would imagine however that due to the increased volume in the 4.5K tank, tethered to your rifle and only filled at the time to 3100 PSI may have created a slight misconception on the number of available shots. Don’t quote me, I may be completely wrong, and way off the mark. One way to get a better idea would be to fill the rifle’s tank to 3100, shoot it down to 2900, count the number of shots in that configuration, then multiply by the number of refills, which if I have this right, or at least the tank calculator is, you would get about 116 fills from 2900 back to 3100. So, if we guess that you can get let’s say 5 good shots within that range on the 490cc bottle filled to 3100 PSI, and shot down to 2900 PSI. If the tank calculator is correct in it’s 116 refills, then 5 X 116, refilling at the 2900 mark back to 3100 every 5 shots would be 580. Again, I am not a math major, and don’t know how the added volume of the 88 cu. ft. tank may have provided more shots withing that pressure range. Sorry I don’t have a great answer, might even be completely wrong, but I too will be interested in what the correct answer is, and since I’m trying to make the new asshole list, I figured I would just toss this out there to see if I can make the list too, or maybe not offend who ever it was that thinks we don’t answers each others post much. Maybe from this they will realize when some of us think we don’t have the right answer, we just read and move on. Hell 80 Grit, I’ll be in your same boat at least for a while, even if I don’t acquire the 257 barrel just feeding two Talon SS’s, and an M-Rod (25) eats up all the two scuba tanks can give, and I have to resort to a hand pump if I want more than 3K in the bottle when trying to sling 43 grain EunJin’s until I find a bullet to try.
Good luck figuring out the right answer, but maybe a test to see how many shots you can get from just the tank on the gun, then maybe the calculation would be simple to figure out, or at least get close.
Casey
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Thanks KQ. When the time comes I will go for it. I will start looking on ebay and craigslist as well. It won’t happen anytime soon…bills are piling up lately…but in the future hopefully.