How much air does an LP85 hold at 2400 PSI?

[JohnnyC]

An LP85 will hold 85cuft of gas at 2640 psi. At 2400 psi it will hold roughly 77cuft of gas. At 3600 it will hold roughly 115cuft of gas.

Your latest hydro says you can only fill your tanks to 2400 psi (no + rating). If they are actually LP85's as you have suggested, they will hold 77cuft of gas at rated pressure.

I'm not sure where the confusion is coming from. This was answered at the beginning of the thread.

A + sign means it is rated for 10% overfill from its stamped rating, and must be renewed at hydro. In your case, since your tanks are rated for 2400 psi with a + when it was made, they could be filled to 2640 psi. Since subsequent hydros did not receive the + rating, the rated pressure is only 2400 psi. And the rated capacity is based on filling to this +10% overfill rating. A + sign does not mean that a tank holds more at the same pressure.

 

[CaveSloth]

I measured the tank diameter twice and got the same number both times: 22.25 " Divide that by 3.14 and you get 7.09" diameter.

 

[CaveSloth]

OK, so it sounds like a + sign or not has no effect on how much it holds at a given pressure. Good to know.

Can someone positively confirm that the plus sign beneath my hydro stamp either does or doesn't have meaning?

 

[tursiops]

Does the + rating mean something regarding how much air is in the tank at a specific PSI? In other words, does a + rated tank hold more air at a given PSI than a non-plus rated tank?

Why is there a plus sign underneath the hydro stamp?

No, and No, to your first paragraph questions.

The plus sign has to be reapplied at each hydro. It was not, so it no longer exists.
It only means you can put 10% more pressure (2640 vs 2400) into the tank, thus 10% more volume (85 vs 77).

If they are "85"s, they now function as 77s.

 

[CaveSloth]

Ok, thanks for finally answering my questions!

 

[rjack321]

OK, so it sounds like a + sign or not has no effect on how much it holds at a given pressure. Good to know.

How would a mark on the outside change how much gas was on the inside? If there's 2400psi in the tank with a + on the outside its 77cf. In there's 2400psi in that tank with no + on the outside its still 77cf.

 

[CaveSloth]

How would a mark on the outside change how much gas was on the inside? If there's 2400psi in the tank with a + on the outside its 77cf. In there's 2400psi in that tank with no + on the outside its still 77cf.

It makes sense to me now, thanks.

 

[CaveSloth]

LOL OK GUYS! I get it! I am a dumbass! Thanks for rubbing it in. I was stupid and I had no idea what the plus sign meant. Maybe I thought it was a bad thing like it meant you had to fill it to a higher pressure to get the same amount of air in. I have no idea what goes on inside my head it's all dusty in there.

 

[Lorenzoid]

LOL OK GUYS! I get it! I am a dumbass! Thanks for rubbing it in. I was stupid and I had no idea what the plus sign meant. Maybe I thought it was a bad thing like it meant you had to fill it to a higher pressure to get the same amount of air in. I have no idea what goes on inside my head it's all dusty in there.

No worries. As they say, the only dumb question is that one you decided not to ask.

Be careful out there in the caverns, dude. You should be able to look at your SPG and figure out how much air (in cubic feet) you have in your tank.

 

[tursiops]

Are you sure these are 85s? You say the diameter is 7 inches (178 mm) and WP 184 bars, then the Faber specs suggest a 10 liter tank.....which holds 1840 liters at working pressure, or 65 cuft. If the diameter is 7.25 inches (184 mm) then the Faber specs suggest a 11.9 liter tank, meaning 2190 liters at WP, or 77 cuft. So maybe the diameter is 7.25 inches, not 7 inches?

The Faber specs also show a 13 liter tank that is 7 inches in diameter and 184 bar WP. That would provide 2382 liter when full, or 84.5 cuft. Is the tank length 26 inches (not incl the valve)?