GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: gene_sc on February 14, 2013, 10:54:08 AM
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You can determin how many fills on your PCP with different size tanks.
Gene
http://www.crosman.com/university/fill-calculator (http://www.crosman.com/university/fill-calculator)
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You can determin how many fills on your PCP with different size tanks.
Gene; Myself, I haven't yet been able to get one of these fill charts to actually give me a reliable reading yet !
I have a Marauder .22 cal., a scuba tank rated @ 3000 psi, @ 80 cu. in. ...... I fill it to 2600, every time. Then when the gun gauge gets down to
2000, I re- fill the gun to 2600. Now, when I enter this info. into this latest fill chart ( below link ) it states 6 refills ! BUT the reality is, I now have 14 re-fills at the present AND am still going ( re- filling to 2600). SO, as you see, I am having a hard time getting actual reliable info. with fill charts. ......Any ideas / opinions ? ......JUST NOW re- calculated w/ the chart and it NOW states - FOUR (4) Re-fills.......Confusing me even more !
http://www.crosman.com/university/fill-calculator (http://www.crosman.com/university/fill-calculator)
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Gene; Myself, I haven't yet been able to get one of these fill charts to actually give me a reliable reading yet !
I have a Marauder .22 cal., a scuba tank rated @ 3000 psi, @ 80 cu. in. ...... I fill it to 2600, every time. Then when the gun gauge gets down to
2000, I re- fill the gun to 2600. Now, when I enter this info. into this latest fill chart ( below link ) it states 6 refills ! BUT the reality is, I now have 14 re-fills at the present AND am still going ( re- filling to 2600). SO, as you see, I am having a hard time getting actual reliable info. with fill charts. ......Any ideas / opinions ? ......JUST NOW re- calculated w/ the chart and it NOW states - FOUR (4) Re-fills.......Confusing me even more !
You have to enter the water volume of the SCUBA cylinder. A typical 80CF SCUBA cylinder has 677 cubic inches of water volume. When I do this and select the Marauder, fill to 2600 and refill at 2000, the calculator shows 34 fills. If I enter what you did (80 cubic inches of water volume), I also get 4 fills. Remember, 80 CF = the volume of air measured at atmospheric pressure that is compressed into the cylinder at a smaller volume (i.e. 677 cubic inches).
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Got it, Thanks......BUT ( right now I am Laughing & smiling ) and kind of in disbelief, only because I have never gotten anywhere close to 34 fills with this tank and this gun ! :o..... AND, at this time, 14 fills, (only going on past fill experience with same gun & tank) I am almost positive that I am VERY close to this tank needing to be re-filled !( meaning of course, down below 2000 psi) .....sperho, what do you think, talk to me !?! And REALLY appreciate you trying to straighten me out !
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If I were to guess, I would say that the cheesy little gauge that they put on the Marauder is not very accurate. :) Other than that, the Crosman fill guide might be a little optimistic as well. Oh, and there is air loss every time you connect and disconnect the gun (hose volume plus what you bleed off to disconnect).
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Note that this calculator says ~34 fills as well. The Marauder has a 215 cc storage capacity. http://www.calc.sikes.us/2/index.php (http://www.calc.sikes.us/2/index.php), so the Crosman fill calculator is in line with theoretical fills. Leakage, gauge accuracy at the gun and the fill station (you might not be getting a full 3000 psi fill) would account for at least some variation from theory.
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If I were to guess, I would say that the cheesy little gauge that they put on the Marauder is not very accurate. :) Other than that, the Crosman fill guide might be a little optimistic as well. Oh, and there is air loss every time you connect and disconnect the gun (hose volume plus what you bleed off to disconnect).
YES , you are very correct and all counts, gauge and wasted bleed off air ! I will keep a very interested eye on # of fills, (as usual) but even more watchful now. Again REALLY appreciate you waking me up on this matter ! Thank you again !
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You're welcome. I've only recently had to start considering these things because I have a Marauder .22 joining the party in the next day or two...
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Thanks Gene, the chart is awesome. It's better than the way I was doing it, you know, fill the Mrod until it wouldn't take a full charge and then start using the Disco... ;D
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with fill locations.
This can be handy, especially if you are new to air gunning.
I contributed to the locations.
Woops! Goofed already. I had not seen your next post down.
Sorry.
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When using calculators where you can enter the gun's reservoir volume, you can sometimes get more accurate results if you enter the reservoir volume about 5 or 10 ccs larger than it actually is. As already mentioned, that can help account for the air that is lost when you bleed the air line.
Lloyd-ss
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Here is another attempt at solving the problem... It is done by using an Excel spreadsheet and scrollbar options....
Malan
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With a Great White it computes 999 fills!
97 cubic feet = 167,617 cubic inches (per Google), @ 4500 psi, to 3000 psi 1st, & 2000 psi subsequent fills = 999 fills.
Could that even be remotely close?
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Vincine
Your units are way off.... I get 76 fills with your values if I fill a Benjamin Disco from 207 to 138 bar....
Malan
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Remember that 97 cu. ft. at 4500 psi is only 8.86 litres of air in my formula....
Convert cu. ft. to litres and divide by 310 to get litres under pressure....
Malan
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Use this Excel spreadsheet.... The previous one contained a lot of background values and reservoir volumes for
different types of PCP rifles....
I assume when you say "3000 psi 1st, & 2000 psi subsequent fills" you mean you fill the PCP to 207 bar the first
time and refill when the pressure on the gauge drops to 138 bar... You also never stated which PCP or what the
volume of the reservoir is, therefore I assumed a Benjamin Disco type PCP.....
Malan
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W0w! one can get a lot of fills out an old $60 scuba tank! thanks for sharing!
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Great information. Thanks, Gene
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With a MAR177 AR upper
80 cu ft SCUBA tank 677 cu in water volume
3000 psi fill
Fill to 2500
Fill at 1500
With these numbers the calculator reports that 46 refills are possible.
Or about one a week for a 10 1/2 months.
Also 46 fills will power about 5000 shots, one sleeve of pellets
This is fairly close to my experience. Historicall, I fill the SCUBA tank, refill 11 months latter to avoid visual inspection costs, and then when it needs a fill for real, about 18 months after the 11 month fill. It also agrees with my pellet burn rate of about one sleeve per year. Which for me is a lot of shooting.
Those 5000 shots saved 10 bricks of 22. Gotta love pellets.
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With a Great White it computes 999 fills!
97 cubic feet = 167,617 cubic inches (per Google), @ 4500 psi, to 3000 psi 1st, & 2000 psi subsequent fills = 999 fills.
Could that even be remotely close?
The calculator is asking for the internal volume of the tank in cubic inches of water not compressed air. A 97cf 4500 psi tank should have an internal volume of closer to 670 cubic inches of water.
I get 75 fills based on 670ci of water.
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OK being easier.
to carry around, anyone know about a 13CF pony scuba tank 300psi
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I use 90ci 4500psi it fills up my Mrod up to 12 times from 2000psi to 2800 and I'm happy with it. I shot about 30pellets with every fill which is a lot and if you out hunting that's Gold! It's light weight and only 5$ to fill it up. Well worth the money.
I wouldn't go for scuba tank unless is 80cf+ and 3500psi+ is just not worth it for me.
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Good information for a newbie like myself. Thanks ;D
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Where do yall get your tanks filled? Or do you have your own compressors? This is coming from a PCP wannabe. ;D
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Dive shops and fire departments are most common places to fill if you don't have a compressor
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I suppose you could fill a small buddy bottle from a large carbon tank? (If I'm going to spend the same $5 for a fill, I would just as soon spend it on the big tank...)
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New to PCP world here. I recently(7/16) got a MROD Gen2 22 Cal and bought a SCUBA tank rated at 80CF @3000. If I can get 15 fills out of it I'll be happy. 15 fills @ +- 30 shots is close to a 500 tin of pellets.
That's about what I shot with Benj. NP1 XL that about 1.5 years old. Given all the great things I've about the MROD Gen2 I might be incline to shoot it more than the my XL because cracking that barrel is getting to get old.
If memory serves me correctly I read they only fill the aluminum tanks to 2700 to allow for expansion.
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New to PCP world here. I recently(7/16) got a MROD Gen2 22 Cal and bought a SCUBA tank rated at 80CF @3000. If I can get 15 fills out of it I'll be happy. 15 fills @ +- 30 shots is close to a 500 tin of pellets.
That's about what I shot with Benj. NP1 XL that about 1.5 years old. Given all the great things I've about the MROD Gen2 I might be incline to shoot it more than the my XL because cracking that barrel is getting to get old.
If memory serves me correctly I read they only fill the aluminum tanks to 2700 to allow for expansion.
Once you get that Mrod rocking, you may shoot a lot more! :D
I'm pretty sure they fill most aluminum tanks to 3300 psi, I'm sure it's at least 3000. The thing is, if they initially fill to 3000 but don't top it off after the air cools, you end up with 2700....
I used my .25 Mrod with a 3300psi aluminum tank for a at least a year, I got at least 15 full fills and lots of partial fills that were good enough.
If you haven't done it yet, Put an SSG in your Mrod. You will almost double your efficiency. Then you can adjust your rifle for a balanced shot string starting at 2700-2800psi instead of 3000 and make the most of your aluminum tank. You will need to buy or borrow a chrony to get through this if you don't already have one. A low end one is about ~70, and will be one of the most important items in your airgun toolbox.
Once you get your gun set up, your XL will be dead to you! ;D ;D But save money for more pellets... ::)
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here ya go seems rather accurate.
seach this calc.sikes.us/2/