AP Air Cylinder Volume

[joe4702]

I'm trying to estimate how many fills I could get from an AL 80 SCUBA tank.
The calculation http://www.airhog.com/tank.htm requires the gun cylinder volume in cc.

What is a typical match AP cylinder volume, say for example on the LP10 or CM162?
I haven't been able to find that detail on the manufacturers websites or by doing general searches.

I'm guessing maybe 50 or 60cc.
Does that sound in the ballpark?

Thanks,
Joe

[Fred Mannis]

What is a typical match AP cylinder volume, say for example on the LP10 or CM162?

The tank for my LP1 is stamped 0.068 L(iters), which would be 68mL or approximately 68 cc.

Would be interested in the results of your calculation

[Nicole Hamilton]

This sounds like a case where precision will likely far exceed accuracy. You can only refill cylinders so long as the pressure in your SCUBA tank is high enough to make it worthwhile. Some (most?) folks try to stretch it out by topping off with a hand pump when the SCUBA tank is only a little low. Also, no one waits 'till the cylinder is empty to refill. Finally, every time you go through the process of filling, you loose some air.

My experience is that one fill on a SCUBA tank lasts about a year. See, wasn't that a lot easier than a lot of math that wasn't going to give you the right answer anyway? :)

[joe4702]

Thanks Fred, looks like I was in the ballpark.

Not trying to come up with exact numbers, mainly
playing with some rough comparisons between AL80 and
various size 300 BAR carbon tanks.

Nicole, about how many rounds do you shoot per SCUBA fill?
That will be more helpful than knowing a fill lasts you 1 year.

Thanks.

[Nicole Hamilton]

Probably about one sleeve, i.e., about 5000 shots/year.

[streamdreams]

I had the problem that my tank is measure in liters not CuFt however

quantity of gas = volume x pressure

so 15L * 232Bar = 3484 liters or air

1 liter = 0.035 314 667 cubic foot

3484L = 122.895 CuFt

and my steyr LP10 holds 68 CC

Which gives an amaising 975 fills !

[Nicole Hamilton]

Which gives an amaising 975 fills !

Well, yes, it'll be amazing if you get that. :)

[jestep]

Refills are a little bit like life -- what you get out of the future depends on what you got out of the past. When the past is empty, there isn't anything left for the future.

Get the SCUBA tank filled every couple of months and use a hand pump frequently to keep your aerobic fitness. Then there will be more past - and more future as well.

Wonder how long it takes to fill a SCUBA tank with a hand pump?????

Jim

[RobStubbs]

I refill my cylinder about every six months and I suspect I get through a tin of pellets every 2 or 3 weeks. That equates to something similar to the above.

Rob.

[joe4702]

Good information. Thanks all.

I can get a new AL80 tank with 200 DIN valve locally for about $165 (incl. sales tax). A similar size CF tank gives probably 10x as many fills, but costs over $500. Going CF would probably only make sense if one shoots a lot of air hungry high-power rifles. The Hill pump with dry pac is ~$250 from our host. Just mulling over the options.....

[Fred Mannis]

Joe,
Many of the field AR shooters in my club use a high pressure carbon fiber tank. But I, for one, would not do that without a regulator to reduce the pressure to 200 bar. One slip and you can destroy a cylinder or cause injury. This was discussed here not long ago - do a search.

Fred

[Pradeep5]

The cost of the CF tanks doesn't make sense unless you tend to move the tank around a lot with you, and a light weight is worth the money.

You can get a reinforced 300 Bar rated cyclinder, for a lot less than a CF tank. $319 for a 106 cuft tank, including 300 Bar DIN valve. There is a risk of overfilling the pistol cylinder tho. You have to make your own choice.

http://www.absolutescubadivingequipment ... y_Code=LUX

Also, you may want to read this, if you haven't already:

http://www.pilkguns.com/scuba.htm

[joe4702]

A 3000psi AL80 tank plus our hosts' yoke/DIN converter gizmo seems to make the most sense for AP. 300 BAR is too expensive once you price in a regulator and risky without one. I just picked up a 2 year old tank in great condition for $85. Thanks for all the input. Now I need to decide on a pistol!

[Mike S-J]

I have to fill my 15 litre scuba tank about every 2 weeks! Oh yeah - but then I also go diving off it. ; )

BTW - any other divers out there who use their breathing-air tanks for refills:
DONT, absolutely DONT, fill your pistol with NITROX / EAN. Oxygen enriched air will react with your o-rings and grease and eventually cause a nasty accident. AIR only. PERIOD.

[joe4702]

Wanted to update this thread with some additional information I discovered.

Another option may be going with a 3442 PSI steel tank, aka HP80.
With a typical 200 BAR match AP cylinder, this tank would provide about
2x the number of fills as an AL80 and a good number of those will
be full capacity (3000 PSI) fills. If you own a Pardini, you'd
be able to fill it's 250 BAR cylinder closer to max capacity.

IMO, the pressure isn't high enough to require a regulator for our use.
You'd still need to be careful not to overfill your cylinder, but I
can't imagine an accidental 15% over-pressure in a 200 BAR
cylinder would be catastrophic. In fact, these tanks typically come with a
combination K/DIN valve for use with standard diving set-ups.
This also means a Yoke-to-DIN convertor is not necessary - the gun
fill adapter will fit right up.

The HP80 also has a size and weight advantage:
~ 6" shorter and 5 lbs lighter than an AL80 tank.

Buying new, an HP80 steel tank with K/DIN valve
is about $65 more than the cost of a standard AL80 + Yoke/DIN adapter
from Pilk.

Apparently these tanks have come on the market within the
last 3 years or so.

Here is a place selling the Worthington HP80 tank for $270 delivered:
http://divesales.com/

These tanks seem to provide some advantages over an AL80 without
the risk or expense of a 300 BAR carbon fiber setup.

FWIW