Silicone vs Buna-N
Silicone is softer than Buna-N. Silicone also remains softer at cool temperatures. Because of this, silicone is supposed to provide a better seal.
I use use Buna-N on my liquid posts because they are cheaper and I figure a leak is going to be very evident – Beer is… visible. I use silicone on my gas posts because they seal better. You cannot see leaking CO2, so I want these to seal as well as possible. This also color codes posts for easy identification. Black o-rings are liquid and orange o-rings are gas.
A Note on Gas O-rings I am quick to replace gas o-rings. This leak is difficult to test for. I lost an entire CO2 tank because of a bad gas o-ring. In bulk, these are cheap, replace them liberally.
Dip Tube O-rings
Buna-N: 109 Buna-N O-Ring, 70A Durometer, Black, 5/16″ ID, 1/2″ OD, 3/32″ Width (Pack of 100)
Silicone: 109 Silicone O-Ring, 70A Durometer, Red, 5/16″ ID, 1/2″ OD, 3/32″ Width (Pack of 100)
Buna-N: 111 Buna-N O-Ring, 70A Durometer, Black, 7/16″ ID, 5/8″ OD, 3/32″ Width (Pack of 100)
Silicone: 111 Silicone O-Ring, 70A Durometer, Red, 7/16″ ID, 5/8″ OD, 3/32″ Width (Pack of 100) - Recommendation: use silicone for pin lock kegs
Buna-N: 417 Buna-N O-Ring, 70A Durometer, Round, Black, 3-1/2″ ID, 4″ OD, 1/4″ Width (Pack of 10)
Internal Ball Lock Quick Disconnect O-Rings
Silicone: 013 Silicone O-Ring, 70A Durometer, Red, 7/16″ ID, 9/16″ OD, 1/16″ Width (Pack of 100)
Theses o-rings aren’t exactly the same as the standard square sided o-ring that comes in quick disconnects, but they do work well for me and this is certainly more economical than buying a whole new quick disconnect. Here is an exact replacement for CM Becker Ball Lock Quick Disconnects.
Pin and Ball Lock
I only use ball lock kegs, but it’s my understanding that pin locks and ball locks use the same o-rings. On the post o-rings, the silicone seems to be the best choice. The flexibility of silicone makes them work better than the Buna-N version on pin lock kegs.
McMaster Carr is also a good source for bulk o-rings. McMaster does charge an additional shipping fee. Their website does not show that. It’s added on after you place your order. To get exact shipping charges you need to call or email McMaster for a quote.
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