# How many CF will This tank hold at 3000 PSI?

I picked up two of these 3000 psi 10 minute geris tanks on eBay two months ago. They are new /unused tanks so I could not resist. I know the threads on the tanks are CGA-346 the standard 4500 psi fireman type tanks are CGA-347.

Can anyone tell me how much air they should hold at 3000 psi. I think they are 11.5 Cubic feet but I am probably wrong.

I have taken photos of the tank and the labels. The photos show it sitting next to one of my 44 Cubic Foot 4500psi carbon tanks.

I was thinking of making it into a pony type of tank to be used for re filling my talon ss tank in the field. Can anyone tell me what I have here?

Thanks

Roger

it looks like 140 min cubic inches, but what does that equal when filled to 3000psi or 3200 psi?

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Viewing 9 replies - 1 through 9 (of 9 total)

Don’t forget to cascade fill your gun… read more here:

http://www.divesports.com/Cascade-Fill-Systems-a/186.htm

You can use one tank to raise the gun to an equalized pressure, bulk filling as much air as possible, and the second tank to top it off to the desired pressure.

Filling your gun to 2800psi instead of 3000psi buys you more fills at that starting pressure. Also consider using one tank for plinking; filling the gun to 2000psi instead of 3000psi while running lighter pellets. Keep your other tank ready for hunting pressure fills of 2800-3000psi… then you can plink on one and hunt on the other.

On my 3000 psi tank, I filled it to 3200, worked ok for a few fillls. I got 8 fills on my 22 marauder (smaller tank only filling to 2500)

Now this trick works really well for a marauder 25 or an air arms where once the small tanks pressure drops to 3k for the .25 marauder or 2800 for the air arms, you can just leave it tethered and shoot the gun to it’s refill point and get many consistent shots without the sharp bell curve. this also means no air is wasted.

To do this I recommend the ninja fill whip for $20

this works great for plinking, or hunting from a bench like I do in Cedarville?

you can also leave the gun connected without bleeding the line between fills, this saves air also.

this doesnโt work for the talon or condor since you need the bottle on the gun to shoot it ๐

but great for marauders, s410โs, discos, 22xx converted pcp pistols, etc.

Roger

P.S. I still have one of the yellow tanks and I use it for the pistol, I now have a 4500 pony tank that I use 90% of the time.

http://www.marauderairrifle.com/forum/viewtopic.php?f=17&t=323

won’t be much good unless you tune your gun for 2500psi or less.

Be a great tank for a Disco or other low pressure gun.

AND a ShoeBoxCompressor to refill it ๐ indeed!!!!

Walter….

Roger,

These 10 min tanks look like they may work good with the new Shoebox compressor.

Fill your Airforce tank and your 10 min tank and your ready to go shooting for 4 tanks worth. How did they work out for you?

> An 80 CuFt. tank holds 80 CuFt. of air at it’s rated max. pressure. No

> matter what size the tank, the volume expressed is at its max. pressure of

> the tank. If i’m wrong, please correct me.

>

Two things:

This is true in theory for an “80 cf tank” in the SCUBA world. However,

in reality a tank labeled as 80 cf will only contain 80 cf of filling-

temperature air at best. The air at bleed-out time may or may not occupy

80 cf if the ambient temperature is different. So “80 cf” is more a

marketing term or rule of thumb than an engineering specification.

Anyway, it was only specified as 80 cf if filled and bled at STP (0C),

and if filled at any reasonable room temperature was more like 75-77 cf.

The meaning of “80 cf tank” has also changed over time. Back in the

day most people used steel tanks at 2600 or 2800 psi,

the standard tank was a certain size, and everybody

knew what you were talking about when you said, “80”. Later

people started using tanks made of better materials and

3000 psi became the standard. “80” still meant something

because the newer tanks were close to the same size.

Now you find 3200 and 4500 psi tanks and steel, aluminum, and

fiberglas variants, and nobody can be sure what you’re talking

about when you say “80 cf tank” because it could refer to several

different physical sizes.

More to the point, not all tanks are labeled by this convention.

AirForce and other PCP tanks are normally specified by internal volume

rather than by the amount of air they hold at standard

temperature and rated pressure. A 160 ci tank in the PCP world

doesn’t mean that the tank holds 160 ci of air, only that

there’s 160 ci of space inside. Air pressurized to 2800 or

3000 psi represents maybe 200 times as much air as the

tank volume, and thus the need for calculators like AirHog’s.

William

An 80 CuFt. tank holds 80 CuFt. of air at it’s rated max. pressure. No matter what size the tank, the volume expressed is at its max. pressure of the tank. If i’m wrong, please correct me.

William,

Big Thanks, for taking the time to answer this.

I may have invested in some fittings. According to the airhog fill calculator:

http://www.airhog.com/tank.htm

Tank Size: 17.9 cf

Tank Fill Pressure: 3200 psi

Fill Gun to What Pressure? 2800 psi

Gun Cylinder Size: 490 cc

Refill Gun When it Reaches What Pressure? 2100 psi

Number of Refills: 3

If I push it, and slowly fill the tank to 3200 psi (using my 4500 psi tanks)

then I may be able to refill my talon tank (to 2800 psi) 3 times ๐

This would be great for when I have to walk in to hunt (or play)

last time I packed in my 44 CF tank. It was bulky and stuck out of my back pack. This may be the perfect solution. ๐ฎ

Thanks again

Roger

I think this is how it goes. If something is off I’m sure somebody

will correct me. Assume all this is done slowly enough so

temperature isn’t a factor.

Say you have a tank that holds 1 cu ft of air. If you now add

another cu ft to the tank the pressure doubles. Add

another cu ft and the pressure triples, and so on.

Atmospheric pressure is about 14.5 psi. To get the number

of cu ft of air to put in this 1 cu ft tank to create a given pressure,

divide that pressure by 14.5. For 3000 psi, 3000 / 14.5 is

207 = “number of cubic feet that must be crammed into a 1 cu

ft tank to raise the pressure to 3000 psi”.

By the way, 207 is also 3000 psi expressed in bars, from

the definition (1 bar = 14.5 psi). See below.

In the meantime, however, your tank is not 1 cu ft, but

140 ci. There are 1728 ci in a cubic foot, so your 140 ci

is 140 / 1728 = 0.081 cu ft. This means that you only have 0.081

times as much air in yours as in the 1 cu ft tank above, so your tank

at 3000 psi holds 0.081 x 207 = 16.8 cu ft.

3200 psi is 3200 / 14.5 = 221, meaning that 221 cu ft have to

be forced into a 1 cu ft tank to raise the pressure to

3200 psi. Again, your tank is 0.081 times as big, so your

tank at 3200 psi holds 0.081 x 221 = 17.9 cu ft.

The easiest way to figure this out is to take the volume of

your tank in cu ft and multiple it by the pressure in bars.

For example, 3000 psi is 207 bar (3000 / 14.5 = 207). A standard

SCUBA tank is something like 0.37 cu ft and change inside, so

it holds 0.37 x 207 = 77 cu ft, which in the SCUBA biz is read “80”.

You can do this in reverse as well. Say a 4500 psi cf tank holds

44 cu ft. 4500 psi is 310 bar (4500 / 14.5). If cubic feet =

volume x pressure in bars, then volume = cubic feet / pressure in bars.

Then volume of a 4500 psi cf tank is 44 / 310 = 0.14 cu ft.

The carbon fiber tank is only 2/3rd again the volume of the small

tank (0.081 cu ft), but it holds 44 / 17 = 2 1/2 times as much air.

Summary:

3000 psi = 16.8 cu ft

3200 psi = 17.9 cu ft

cubic feet = tank volume in cu ft x pressure in bars

William

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Also, check this out for a quick “volume x bar = fill volume”

http://www.wolframalpha.com/input/?i=140+cubic+inch+x+207