explain tank sizes to me

[phantomhitman]

Ok, I have never really thought about tank sizes and pressures up until last night. I am looking to buy a 45-45 hp tank by the way. It is quite obvious a 114 4500 holds more than a 68 4500, but which has more shots a 45-45 or 68-3? The 68 has more ci, but less air it can hold, while the 45 is smaller in size but holds 4500psi. Also, I do not know if they make these tanks but just humor me, If I had a 45-5000 and a 68-5000 what is the difference besides the size of the tank? I mean they both hold 5000 psi, so does that mean the 45 is a stronger tank because it is smaller but still holds as much as the 68? Or is there another difference such as I cannot get as many shots off of a 45 compared to the 68?
Sorry for my confusion, it happens all of the time.

[diaper eater]

all i can really answer is your last question, a 45/5k holds 45 cubic inches of air at 5000 psi, while a 68/5k holds 68 cubic inches of air at that same pressure, so the 68 ci tank holds about 1.5x as much air, and thus will have 1.5x as many shots.

[Pickle]

as I understand it....the formula for shots per tank (automags) is as follows.

3000 psi = 10 shots per ci
4500 psi = 15 shots per ci

so 45/45 would be approximately 675 shots

[Blazestorm]

48*3000 = 144,000 in*lbs
68*3000 = 204,000 in*lbs
88*3000 = 264,000 in*lbs
114*3000 = 342,000 in*lbs
45*4500 = 202,500 in*lbs
68*4500 = 306,000 in*lbs
88*4500 = 396,000 in*lbs
114*4500 = 513,000 in*lbs

Because mags use 220 in*lbs per shot, but they can not use the last (TankSize)*(600) in*lbs because they do not operate on the last 600psi

To figure how many shots you'll get, take the amount of air you can get, and divide it by 220, but also don't forget to subtract the last 600psi you can't use. That'll be about how many shots you'll get.

To give you an idea how other guns use their air...

Vikings + Excals - ~150 in*lbs
03 Shockers - ~300 in*lbs
Old Shockers - ~385 in*lbs
Stock Spyders - ~250 in*lbs
Stock Tippman - ~250 in*lbs
Freestyle w/ HE Bolt - ~250 in*lbs
Freestyle w/o HE Bolt - ~300 in*lbs
Tuned Stock Cocker - ~165 in*lbs

These are all figures done by Josh, he's gotten cockers and spyders to the 200psi range.

Equation and leet information provided by PBJosh (He's smart...)

[shatter_storm]

The first number is the number of cubic inches of air the tank can hold, or the capacity, also known as the volume of the tank. The second number is the pressure the tank is rated for, generally 3000 or 4500 PSI.
The primary factor in air capacity is the size of the tank. A 45 cubic inch tank is considered small, the 68's are normal size, 88 and 114 cubic inch tanks are large and massive, respectively. There are also "stubby" 72 cubic inch tanks that are shorter than 68's, but fatter by a large margin.
The secondary factor in air capacity is the pressure the tank can hold. One thing to get familiar with is your cutoff point - the PSI level where your marker system will cease firing. Another thing to remember is that the tank will always have the highest pressure, and every step further down the line towards your marker you go, the lower the pressure will be. The tank itself may hold 4500 PSI, but the tank reg drops that to 1200 PSI or less, usually 800ish psi. You can never regulate air upwards to higher pressures, so once the tank's pressure approaches the cutoff point of your marker, it can be considered empty.
So, an example. My 'mag stops firing around 500 PSI. I use a 68/4500 tank. That means I get about 4000 PSI worth of usable shots out of it (4500 - 500), then my freshly filled tank won't be putting out enough pressure to be usable.
Now, I borrow a friend's tank, a 68/3000. I now only get 2500 PSI worth of usable shots (3000 - 500) and I will run out of air sooner. They're both the same "size" tank, one just holds higher pressure and thus more energy.

You'll get more shots off of a 68/5000 tank than you would a 45/5000 tank. That's due to air capacity. You'll get more shots off of a 45/4500 tank than you would a 45/3000 tank. That's due to air pressure.
Stack a 45/4500 up against a 68/3000 and you'll see that they've almost exactly equal, assuming you fill them both to their rated pressures. The 45/4500 will be smaller and lighter because of it's size and probably because of it's construction. Fiber bottles (fiber-wrapped tanks) weigh a lot less than an aluminum or steel tank does. 4500 tanks are almost always fiber, 3000 tanks can be either fiber, aluminum, or steel.

[Blazestorm]

4500 and 5000 are always aluminum casing wrapped in carbon fiber.

3000 are Steel, and aluminum casing wrapped in carbon fiber. I haven't seen pure aluminum tanks yet, Those would be very light.

[shatter_storm]

Not to jack the thread, but if mags use ~220 in*lbs per shot and the shockers, spyders, tippmanns, and the freestyle all have higher amounts, why is the mag considered a gas hog? Shockers, the freestyle, other electros are LP and can shoot further into the tank, but that 400 PSI doesn't make that much of a difference.

For example, using a 68/4500 tank with 306,000 in*lbs of air:
A mag stops shooting at 600 PSI, giving it 306000 - (68*600) = 265200 in*lbs of usable air, or 265200/220 = 1205 shots.
A '03 shocker stops shooting at 200 PSI (wild guess, I don't actually know), giving it 306000 - (68*200) = 292400 in*lbs of usable air, or 292400/300 = 974 shots.
A freestyle with a HE bolt stops shooting at 200 PSI (another wild guess), giving it the same 292400 in*lbs of usable air, and thus 292400/250 = 1169 shots.
A viking stops shooting at 200 psi (guessed), gets the 292400 in*lbs of air, and then 292400/150 = 1959 shots.

Now, I'm probably wrong about the cutoffs at which the shocker, freestyle, and viking stop functioning, but I'll be nice and say they can shoot down into the tank that low. Obviously, the viking has the crown for efficiency. The mag isn't that bad in comparison - so what are we missing? Why is it a "gas hog"?

[shatter_storm]

and for a little anecdotal evidence, I know I blew through seven pods and one hopper in a woodsball game on a fresh fill before my air ran out. That's almost 1100 shots, plus a bit of air for LX chuff and flash fill shrink would give us the 1205 number I calculated earlier.

[Blazestorm]

They have a .55ci Dump Chamber, and run at 400-450psi correct?

That's how you figure out how much they use.

[phantomhitman]

you guys more than answered my question. thanks for the help, i have to walk away from this thread before i confuse myself though, lotta numbers in here

[Glickman]

heres the easiest way:

45 x 4500 = 202 500

68 x 3000 = 204 000

so the 68 holds only a little more, while the 45 is smaller, id get the 45