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**lookatme123** · November 24th, 12:20 AM

hi, my friend just got a scuba tank, and a fill station. I was trying to do some calculations to figure out how many fills from the scuba tank will i get into vaious sizes of paintball n2 tanks. but the numbers i got didnet seem right. So i was wondering if anybody knew how many fills could I get from a 80 cubic foot scuba tank, into a 48 ci tank, a 72 ci tank and a 88 ci tank, at 3000psi Or simply the formula to do so. Thanks.

**Angered Fists** · November 24th, 12:32 AM

It depends on the size and pressure of the scuba tank. I can assume you meant that it was a 3000 psi tank since you want 3000 psi fills, but you should specify.

Edit: I should also let you know that each fill will give you less and less shots because as you use more and more air from the scuba tank, the pressure in the tank drops, so the pressure that it is able to fill your tank up to decreases. For example, your first fill will be 2999.9 psi. Your second fill might be 2950 psi. Your third might be 2900 etc. etc. Just made up numbers to help you understand.

**lookatme123** · November 24th, 07:28 PM

ok thanks, the scuba tank max is 5000 psi, but most of the people getting fills have 3000 psi tanks.

**Angered Fists** · November 24th, 07:33 PM

It must be the fill station that is the limits the psi that you fill with then, because if you hooked a 5000 psi source to a 300 psi source, you would damage your tanks. I don't know too much about fill stations, but that would be my best guess, just be sure that its filling 3000 psi and not 4500. What I really needed was the size of the scuba tank in cubic inches, without that I have no idea of how many fills you can expect to get.

**Raydee** · November 25th, 07:49 AM

From what I was told by a guy at my local field you will get 2 full 3000psi fills and then the pressure will drop. He says after the full fills he gets a total of 11 fills from his 80 cubic foot scuba tank into his 68 cubic inch N2 tank with the last few fills only filling to 1400psi or so. Scuba tanks are a good idea if you play alot outside or if your local field rapes you on air but most places charge one price for "All day air" and it not worth lugging the scuba tank around and having everybody at the field ask for a fill.

**Angered Fists** · November 25th, 11:17 AM

Technically even the first fill isn't a 'complete fill'. This has been explained in other threads before, but basically when you hook up your tank to your scuba tank, it just balances the air between the two tanks, so if your scuba tank was 3000 to begin with then your hpa tank can not be filled to 3000 psi. It is not possible.

**Bubbahotep** · November 25th, 01:05 PM

well if the scuba tank and ur tank operate at the same pressure, you will only be able to get one truly full fill when the scuba tank is 100% full. Every fill after the first is lesser and lesser. I could get about 10 sufficient fills, before having to refill.

**lookatme123** · November 25th, 01:11 PM

ok thanks guys. "so if your scuba tank was 3000 to begin with then your hpa tank can not be filled to 3000 psi. It is not possible." wouldent the first couple of fills be full fills sence the scuba tank has 5000psi and we are olny filling tanks to 3000psi? then start dropping off?

**paintthecatBLUE** · November 25th, 05:23 PM

read the first post in this thread Got a question about Scuba tanks? READ THIS!

i don't get the math but at the end it says both cylinders will end up with 2934 psi after the first fill. read it and maybe you can find the formula.

edit: i get the math now, the pressure per volume of both tanks divided by the combined volume of both tanks gives you the psi both tanks will have at the end of the fill. pressure per volume is found by psi times volume, like it sounds, so theres your formula

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