HOW MUCH PSI IN A NEW 5lb BOTTLE

[DD2000GT]

I just got a new CO2 canister due to my last one being 6 years from the last certification. If I remember correctly, the last time I got my CO2 filled it had 1200 psi of pressure on the guage. I just got it replaced because the psi dropped down to 550 and was in the red "Refill Gas" area. Well I got the new one home and hooked up the regulator and it only shows 600 psi... I measured the weight of the canister minus the tare weight and it comes up to 5 lbs - so why is the psi only at 600?

What is the normal amount of psi you guys are seeing on a new 5 lb. tank?

 

[Chester]

It depends on temperature. The colder it is the less pressure the gauge will read. Don't worry about it, the weight is what matters.

 

[Yooper]

Yeah, those gauges are pretty useless. It'll say "600 psi" until the tank is nearly empty, and then go to 0 in 5 minutes.

If you put your tank in the fridge, the gauge will read even lower! But the same amount of gas is in there.

 

[wilserbrewer]

What is the normal amount of psi you guys are seeing on a new 5 lb. tank?

No normal psi as it is temp dependant. The only real value the second gauge has is when it plummets you know you will be out of gas in a few beers.

 

[Julohan]

Yeah, those gauges are pretty useless. It'll say "600 psi" until the tank is nearly empty, and then go to 0 in 5 minutes.

If you put your tank in the fridge, the gauge will read even lower! But the same amount of gas is in there.

The first and only time my tank emptied it did this. Gauge showed it was full, the next day empty. I thought maybe I had a leak.

When I get my tank refilled again, would it be better to have the tank at room temperature before getting filled?

 

[DD2000GT]

Thanks guys - this makes perfect sense. The temps are in the low 30's now and the guy got the tank from the warehouse (unheated I am sure). I am letting the tank warm up to inside room temp and hopefully it will be closer to 850 psi or so. I did weigh it on the bathroom scale - it weighed 14.4 lbs with the regulator installed and the tare weight of the bottle is 7.5 lbs - so it is indeed a fully filled tank. I always thought the psi was an indicator of how much CO2 I had left - your description is great to know.

I got an aluminum bottle when I swapped it out - it is MUCH lighter than my old steel one. Not sure if there is any advantage to steel over aluminum, but since I lug it back and forth between kegs I opted for the lighter version.

 

[lamarguy]

Not sure if there is any advantage to steel over aluminum

Sure there is. If you catch someone stealing your beer, the steel tank is a more effective lethal weapon. More "thud"!

 

[Pick]

Guys, the reason the pressure gauge behaves the way it does, is because the CO2 is a liquid in the bottle. Your gauge is reading the vapor pressure at the current temperature. So, as long as there is liquid in the bottle the pressure will remain constant if the temperature is constant, until the liquid is all vaporized. Weighing the tank before and after filling would give you a better idea of your CO2 usage.

Propane in tanks behaves the same way. Those propane tank gauges that go between the tank and your grill will operate the same as your CO2 tank gauge.

 

[david_42]

I had steel tanks when I moved to Oregon. The guy at the welding shop asked me if I minded aluminum. Heck no, a full aluminum tank is lighter than an empty steel one!

When your gauge hits 200 psi, you're on fumes and should get a refill. I've got two tanks and run down to 40 psi before swapping.