lp 108/ how much cubic feet

[scubamarcp]

I was wondering how much cubic feet of air can you get into a lp 108 if you over fill it

Thanks marc

 

[dsteding]

The answer, in the words of my AOW instructor is, "it depends."

How much are you overfilling it?

Assuming an LP 108 is full at 2640 psi, the tank factor (cubic feet per 100 psi is about 4.10 or so (don't have a calculator, take 108/26.4 and you'll get the tank factor in cubic feet per 100 psi).

For example, if you want to take this puppy to say, 3000 psi (and I'm not discussing the merits/negatives of overfilling tanks, just answering your question) you'll have 360 psi more than at full, or just under 15 more cubic feet. Your LP 108 is now a MP 123 . . . take it north of there, and you'll obviously have more air, but the 4.1 cubic feet per 100 psi factor will allow you to figure that out.

 

[Archangel]

And then you pick up your VERY WARM tank with the beautiful 3200 psi fill from the 'fill monkey" and happily hit the water only to find you are back to 2700 due to Charles Law.

 

[The Kraken]

Well, to determine that would call for a destructive test of the tank.

One would attach a pressure gauge with a max pressure indicating hand and fill it until it exploded.

Now, a more pragmatic question would be, "Can I fill, safely, a LP 108 cubic foot capacity tank to ??? (put cubic feet or psi here).

the K

 

[bjpell]

I pump my lp 120's to 4200 psi, let them cool, and do it again so ending pressure is about 3,900-4100 psi. They hold something like 180 cubic feet of air at that pressure. Something to consider is that I have aftermarket hp steel valves and there burst discs, you might want to think about doing this also. Don't let your tank sit long with a hot fill in em, they will likely fail your next hydro if you do. My tanks are 10 years old and just made there last hydro a few months ago, but at this rate I will be lucky to see another passed hydro. I use mine ASAP when getting a "cave fill" in my tanks. With that kind of air in one tank I get almost 4 hours under water at 10-20 ft on the reefs here in sofl.

 

[scubamarcp]

thanks alot guys for the info

 

[PerroneFord]

4200psi eh? Thats a whole lotta pressure on gear.

 

[bjpell]

yeah, thats a lot of pressure, but most gear is made to handle it. My poseidon regs don't mind it. The only downer is the safety issues. Having a tank with more pressure in it then its hydro'd at?!? hydro for a lp is 4,000 psi by what Dive Rite Fill Express tells me, but they fill it up for me every time and don't seem to mind....

 

[loosebits]

Yep, 3600 cold on my LP104's is about as high as I want to go but I always get a bit nervous when they were sitting at 3600 psi when its 50 deg outside and then I get in the nice warm springs... 3700, 3800... time to dive.

How do you know when your tanks are full? When your turn pressure is stamped on them.

 

[diveAK]

thats great, when the turn pressure is stamped on them...