Floating CO2 barrier creator for filling homebrew beer kegs

thingiverse

This is a design for a circular float that sits on the surface of homebrewed beer as it fills a keg. This float has two flat surfaces that are held a fraction of a mm away from each other. A stream of carbon dioxide enters the center of the float and escapes from the small gap at the circumference. In this way, carbon dioxide is distributed sideways over the complete surface of the beer as it fills. This helps isolate the beer from the air above it which could otherwise degrade the beer through oxidation. This device is designed to minimize the use of tanked carbon dioxide when filling kegs. Only a few liters of carbon dioxide are needed to fill a 5-gallon Corny keg whereas to fully purge the keg by simply blowing carbon dioxide into the keg would take over 100 liters. The use of this device was described in an article entitled "Mitigating the Need for Pressurized Carbon Dioxide in Homebrewing" in the July/August 2023 issue of the Zymurgy magazine published by the American Homebrew Association and Brewers Publications: https://www.brewerspublications.com/collections/zymurgy-magazine Because of the direct contact of the float with beer to be later consumed, the materials and processes used to make this print should be food safe by adopting the following: * Use PLA or PETG filament * Use a stainless steel nozzle * Coat the final part with food-safe epoxy resin or silicone A few other parts are needed: * A M5 fitting with a 3-mm barb which is screwed into the center of the float top surface (can be brass as it doesn't make contact with the beer) * 2m of 1.5mm i.d. thin-walled silicone tubing which is attached to the barb fitting * A means of supplying and controlling 100 to 500mL/min of food grade carbon dioxide which is connected to the silicone tubing In use, the float is lowered into an empty keg. A flow of 500mL/min of carbon dioxide is applied to flow through the silicone tubing. After 2 minutes, beer is fed to the base of the keg. As the beer level increases, the float will move with it and maintain a barrier isolating the beer from the air above it. The carbon dioxide flow rate can be reduced to 100mL/min for most of the filling process. Once filled, the keg can be sealed and the headspace pressure-pulsed with pressurized carbon dioxide to remove any residual traces of air.