How much PSI is a full 5 lb. tank?

[av8er79]

Ok, I am new to kegging. Picked up some kegs off craigslist and purchased the rest from Keg Connection. I took my 5 lb. tank to the local paintball shop to fill. He filled it for 10 bucks. I got home and after hooking up the regulator it indicateded 850 PSI. When I called and asked him about this, he replied that he fills these for homebrewers often and it is sold by the pound not PSI. He tells me that my 10 bucks got me 1 lb. I have since force carbed my first keg and the regulator is now in the red. ???? Did I get ripped off?

 

[av8er79]

guess i should have done a little more research. I think this answered my question.

https://www.homebrewtalk.com/f35/how-much-co2-psi-5-co2-tank-122590/

 

[zachattack]

If you want to know exactly what the pressure should be:
http://en.wikipedia.org/wiki/Carbon_dioxide_data#Liquid.2Fvapor_equilibrium_thermodynamic_data

 

[solbes]

Yeah if you're really worried about it, get a mass scale thats accurate in the weight range of your tank. If it read 850 psi, then you got your 5 lbs of CO2 or close to it I would venture.

The pressure will drop ~ 150-250 psi when you chill it from 80F to 35F in the fridge. Many people get scared about this. Basically your high pressure gas gauge is worthless, I put very little stock into what it says.

 

[badbrew]

Ok, I am new to kegging. Picked up some kegs off craigslist and purchased the rest from Keg Connection. I took my 5 lb. tank to the local paintball shop to fill. He filled it for 10 bucks. I got home and after hooking up the regulator it indicateded 850 PSI. When I called and asked him about this, he replied that he fills these for homebrewers often and it is sold by the pound not PSI. He tells me that my 10 bucks got me 1 lb. I have since force carbed my first keg and the regulator is now in the red. ???? Did I get ripped off?

That makes no sense. Who is going to buy 1 lb of co2 for a 5 lb tank? And 1 lb for $10 is a big rip off too. I think you may have a leak. 850 psi is probably right at 70 degrees and then 500 psi at 40 degrees.

 

[audger]

If it read 850 psi, then you got your 5 lbs of CO2 or close to it I would venture.

you would read 850 psi if you had 8oz of co2, the same as you would if you had 5 pounds. pressure does not relate to weight at all. your tank will read full pressure when it is anywhere between 100% and 5% full. only when the last drop of liquid CO2 is gone does the pressure start to drop.

the only way to weigh your tank is to actually weigh it.

 

[av8er79]

Solbes, you are saying that 5lbs in a 5lb tank is about 850 psi?

When I first hooked it up the psi indicated 850 and that concerned me so I called the shop and he told me that that i should not pay much attention to the psi since co2 is sold in a liquid form.

 

[zachattack]

Solbes, you are saying that 5lbs in a 5lb tank is about 850 psi?

When I first hooked it up the psi indicated 850 and that concerned me so I called the shop and he told me that that i should not pay much attention to the psi since co2 is sold in a liquid form.

He was saying that, but like audger said he's incorrect. The pressure is independent of how much liquid is in there, as long as there's some liquid it's just a function of temperature. Once it really starts dropping it means you're out of liquid and you'll go through the remaining CO2 very quickly. The VLE data that I linked to will tell you the exact pressure at various temperatures.