Keg to Keg Transfer - 5 gal to 2.5 gal?

[Hagelslag]

I recently got a 2.5 gal corny and I'm looking to do my first transfer from a 5 gal corny. I've read up on the forums about the jumper method, but my question is:

How do you know when the 2.5 gal corny is full?

Checking with my fingers to see if its cold won't work because I plan on cooling my 2.5 down to reduce foam.

I don't want it exploding , or more importantly, squirting beer everywhere..

Do I just leave the pressure valve on the 2.5 open until beer comes out?

Thanks in advance.

 

[Gritsak]

If the beer you're transferring is cold, you should have condensation on the outside of the keg that closely approximates the level of beer. You can also just open the lid and look when it gets close.

If you wanted to go really overboard, you could fill up the 2.5g keg with water and weight it, then keep the keg on the scale when transferring. When it gets close to that weight it's close to being full.

 

[Cpt_Kirks]

You're not going to explode the little keg.

If you find that you have over filled the 2.5 gallon, just move the gas line over to it and squirt some of the beer back into the 5 gallon.

 

[betarhoalphadelta]

You know, I'll probably be lynched for this, but when I'm filling my 5 gal kegs (I brew 10.5 gallon batches so I can't just fill until I run out of beer), my kegs are usually full of starsan foam, to the point that the starsan foam is erupting out of the the corny lid like a volcano. And I can't see the beer level in the keg.

So you know what I do when I know I'm getting close to the top? I dunk my hand in starsan, put my finger at the bottom of the CO2 tube, and fill until I can feel cold liquid on the other side of my finger. I get a fill to within one finger-width of the bottom of the CO2 tube.

If you don't like the option that requires you to touch the beer, I recommend just using a sanitizer for the 2.5 gal keg that doesn't foam up like starsan, opening the lid, and watching the fill level as you go.