starting to Keg : questions about CO2 volume

[m3B.eer]

Hi everyone. I'm starting to Keg and purchased a 20lbs cylinder, supposedly close to being full.
It came with a N2 regulator for which I bought a adaptor for a CO2 tank.
The tank is fairly heavy, 40lbs.
When I connected the regulator to my 5gal keg, in order to carbonate it, I set the pressure to be just below 10psi to the keg. Temperature here is close to 0C where I'm carbonating. and the tank volume gauge reads 500psi, and slightly less this morning.
I'm wondering how can I now how full is this tank? I hope I wasn't tricked, because it shows in the red zone.

 

[sifty]

I've just kegged my first brews too. Sadly a faulty o-ring on the keg fitting drained my cylinder of gas. Very disappointing as I'd spent ages checking the lines and fittings for any leaks. I noticed the main pressure gauge had dipped slightly, and next day it was empty. Typically when the gauge starts dropping it is close to empty.

Refilled the cylinder and new o-ring with some keg lube and all seemed well. Then I noticed the gauge had dropped again..? However, this coincided with a change in temperature in my garage. The main pressure gauge will change with temperature. It's since gone higher than when I received it after things warmed up, so all seems well.

If you have no leaks and temp hasn't changed the only way to confirm gas level is to weigh the cylinder.

My 5kg cyl weighed 12kg full (with regulator attached) and 7kg empty, so the 5kg charge seemed accurate...

 

[marc1]

Is the tank also being cooled? If you chill the tank it will show a pressure drop.

The only way to see how full the tank is, is to weigh it. There should be a tare weight stamped into the tank somewhere so that you can see what it weighs when empty.

 

[m3B.eer]

Thanks for the feedback guys.
When I purchased the tank there was one similar with the plastic wrap, they were close to being the same weight (filled then) of 40lbs.
I did look on the cylinder but there is no clear mention of empty weight/tare weight. I could show you but I don't understand the numbers on it. The tank is in the garage with the keg now close to 0c. That could be why... I hope.
I checked for leaks with water spray and all, the prong on the keg seems to fit well. And I don't here and pressure sounds anywhere.

 

[GilSwillBasementBrews]

Can you post pics of the cylinder. I’m sure someone will be able to help point you in the right direction. I’m fairly certain all tanks have a tare weight stamped into them. I could be wrong. If so I will be corrected.

 

[m3B.eer]

I got home and took some pics... Best I could get right now.

 

[GilSwillBasementBrews]

I’m pretty sure the tare weight is the 27.0lbs stamped into the collar.

 

[m3B.eer]

Good point, I couldn't tell if it was 270lbs.
If 27lbs and I got a scale at 40lbs... I got screwed 7lbs :-(