Using corny kegs for fermenting - checking gravity?

[aangel]

So I'm thinking of using old corny kegs to ferment, if only because I've found closed transferring with my better bottles and racking canes to be really awkward. I have a couple questions though:

1 - how can I check gravity with this kind of setup? I don't have a refractometer...would this work?

Use gas-in post for blowoff. When taking a sample, hook up liquid-out post to a picnic tap, close the gas-in post, and let the wort be pushed by co2 pressure out the liquid out post into a hydrometer jar.

I guess if fermentation wasn't vigorous enough I could attach my tank to the gas-in post and just push the liquid out?

I guess in this situation I'd have to cut the end off of the liquid-out post so as to suck up beer and not trub.
So...will this work?

 

[sarsnavy05]

aangel,
There are quite a few posts on this, but it definitely works.
This is the way that I typically ferment my beer.

You can check gravity either the way that you describe through the liquid out post or by opening the lid and pulling a sample with a wine(beer) thief. Opening the lid is probably marginally less sanitary, but proper technique will remedy that. I'd actually recommend this method, since most of my pressurized fermentations seem to have taken longer than ones that were allowed to freely vent CO2.

No modification is necessary to the liquid pickup tube, because once the yeast cake and trub are set in place, they should leave a space around the tube after the first few times that you pull a sample.

 

[firerat]

The only issue I've ever had with fermenting in a corny keg is capacity. A 5 gallon batch with a good fermentation can be messy. 4 gallon or less batches would be perfect though.

I have a modified corny lid with a drilled bung and an airlock attached to it for such uses.

Opening the lid to take a sample is no more "dangerous" than opening the top of a bucket to get a sample.