I'm looking at purchasing a stainless steel carbonation cap.
If you do a Google search for "stainless carbonation cap" you can see them listed at lots of online brewing stores.
Most of these online stores list the following uses for the cap:
- Cleaning your beer lines
- Use it to counter pressure bottle fill PET bottles
Numbers 1 and 2 make sense to me. However, number 3 is confusing me. How can you counter pressure fill a bottle if there is no way to vent the CO2 as you fill the bottle with liquid. I know that the cap I'm looking at has a barb so you cap put a dip tube to fill from the bottom up but I would have thought that no beer could flow into the bottle if it is sealed and full of CO2. Are all these homebrew stores just putting the wrong description on these caps or am I missing something?
I suppose maybe you could undo the cap a little bit to let the CO2 escape as you fill the bottle. Has anyone done counter pressure filling with a carbonation cap?