cabonation and specific gravity

[g-nub]

I use a closed system and do my secondary in a keg. I used to put an airlock on it, but figured the extra natural carbonation wouldn't hurt. When I take gravity readings the beer is part carbonated. I was wondering if carbonation effects the specific gravity reading (If I had something on tap now I guess I could see if the S.G. of my beer matched my F.G., but I don't).
Thanks
-G

 

[Orfy]

Anything dissolve in a liquid will affect gravity.
I'm not sure how gas will change the reading. I guess it will give a lower gravity reading.

If you degas it then you should get a true reading.

 

[g-nub]

If you degas it then you should get a true reading.

I could release the pressure but it will still be slightly carbonated.

 

[Orfy]

Can't you take a sample?

 

[g-nub]

I take a sample from the keg with a hand held tap into the hydrometer tube. It shoots out from the natural carbonation and the I wait for the bubbles to go down. There is still a small amount of carbonation (and meanwhile, things (yeast etc.) are separating in my sample).

 

[Orfy]

That's what you want.

After it dies down stir/agitate it until there are no bubbles left.