I decided to rearrange this post to be a little more straight forward with the information. The bulk of the info provided here was copied/edited/paraphrased from a Dec 2010 post on Homebrew Finds - so a big thanks to Chris (724b). Rather than copying the blog post's text, I have pared down to just the relevant details no so this is easier to read at a glance. The links and numbers below are currently for ball lock kegs, but if you have the numbers/links for the o-rings for pin locks please let me know and I will add them to the list.
Regarding Buna-N vs Silicone:
Most use Buna-N on the liquid posts because they are cheaper and a liquid leak will be immediately obvoius. Silicone is supposed to seal better, and is generally used for the gas posts. This also has the effect of color coding the posts as Buna-N is black and Silicone is red. Though the keg lid is generally sealing against gas coming out, most use the Buna-N for lid sealing without any problems.
Notes/Additional O-Rings:
I will list extra info and additional o-rings and part numbers here until I have enough to start reorganising it by keg type or similar.
- Dip Tube O-rings $1.96/100 - 9452K172
- Dip Tube O-rings Quad Sealing $4.46/100 - 90025K368 (better seal, less force)
- Post O-rings Buna-N $2.15/100 - 9452K23 (liquid post)
- Post O-rings Silicone $10.71/100 - 9396K24 (gas post)
- Lid O-rings Buna-N $12.69/10 - 9452K218
- Lid O-rings Silicone $7.88/5 - 9396K926
- Internal Quick Disconnect O-rings Silicone $6.11/100 - 9396K18 (see notes)
Regarding Buna-N vs Silicone:
Most use Buna-N on the liquid posts because they are cheaper and a liquid leak will be immediately obvoius. Silicone is supposed to seal better, and is generally used for the gas posts. This also has the effect of color coding the posts as Buna-N is black and Silicone is red. Though the keg lid is generally sealing against gas coming out, most use the Buna-N for lid sealing without any problems.
Notes/Additional O-Rings:
I will list extra info and additional o-rings and part numbers here until I have enough to start reorganising it by keg type or similar.
- The o-ring listed for the Internal QD (9396K18) aren't exactly the same as the standard square sided o-ring that comes in quick disconnects, but the HBF author stated they work well for him and I have found this to be true as well.
- Dip Tube Silicone o-rings $9.44/100 - 9396K74 (thanks crazyworld)
- Sanke Keg o-ring $4.67/10 - 9396k215 (thanks dstar26t)
- barrooze reported that the standard post o-rings for ball locks appear to be a bit small in thickness for use on a pin lock post and he will try using the next thickness up (0.139").