Capping on foam
I have a co2 jetter in front of the capper to create a foam to evacuate the air in the headspace. How ever sometimes during a filling day there is a good foam already from the filler. When the bottle with foam comes under co2 jetter, the jet stream do not go through the foam so it just compact the foam so there will be a space between the foam and the cap. Can I assume that this space mostly consists of co2 or air? (I think that the foam created during/after snifting comes from to low pressure in the filler bowl combinated with bad gaskets in the filling valve so the filling valve do not close properly. The problem is more common when the pressure in the BBT goes under 0.7 bar. The cent. pump makes about 0.5 bar so the pressure in the bowl goes down to 1.2 bar.)
CO2 and air content
Co2 is heavier than air, so theoretically the bottle should stay completely filled with beer and a "head" of CO2.
Reality however is that because of the movement of the bottles between the filler and capper, there is air flow over the top of the bottles, eroding some of the CO2 and replacing it with air. When capped, the air is trapped inside the bottle.
Solutions here are:
- Replacing your CO2 fobber with a sterile water fobber.
- Getting better control over your carbonation and filling so that the bottles are so full or overflowing and that you do not need a fobber.
- Replacing the head of your CO2 fobber with one of a smaller diameter and increasing the pressure (manometer works great here). Moving the fobber further away from the filler will also give the head more time to rise again.
Let me know how it goes!
Last edited by BelgianBrewer; 04-05-2008 at 01:35 AM.
Now I have run about 20.000 bottles with jet water and co2 jet combinated, with good result. I just need to add a small valve to the water inlet so I can adjust the flowrate depending on the dispolved co2 in the beer / temp
It seems as water goes through the initial foam better than co2.
Our filler uses 190º F water for jetting. The hot water has less oxygen in it and requires less volume jetted into the bottle, it works great. After we fill a bottle, we tip it slightly on it's side. If you see just small bubbles and foam as you tip the bottle on it's side you did a good job of getting the air out, but if you see a very large air bubble (larger than 1/4 inch) then you have air in the bottle and need to jet harder. It's a good quick test that works.