By Paul Mahoney, Head Brewer at Launch Pad Brewery and Danny Wang at Fermly/Black Shirt Brewing
Overview:
Excess dissolved oxygen (DO) in finished beer reduces flavor stability and shortens shelf life. The brite tank is one of the most critical points of oxygen ingress in the cellar. By using a DO meter to measure DO/CO₂ in real time, we were able to dial in our purge and transfer process. By slowly filling our brite tank from the bottom port and venting CO₂ from the CIP arm we found that we had more complete oxygen displacement during tank purging. We tried multiple methods of purging brite tanks and found the following results:
- Purging through the carb stone at normal carbonation pressure: Very poor results, very high DO readings.
- Multiple CO₂ fill and vent cycles: Solid results, but a lot of wasted CO₂.
- Slow purging from the bottom, with a T fitting: Lowest results, minimal CO₂ waste.
Tank Preparation and Purging
- CIP & Sanitize: Always start with a clean, sanitized brite tank with all tri-clamp fittings attached.
- CO₂ Purge Procedure (CIP Arm Venting):
- Purge Carbonation Stone with CO₂.
- Introduce CO₂ into the tank from the bottom inlet/beer port. Set regulator for around 5 PSI. We recommend a slow flow of CO₂, to avoid as much turbulence as possible. This “bottom-in, top-out” purge uses CO₂’s heavier-than-air property to push O₂ out efficiently.
- Allow oxygen to be displaced upward, venting from the CIP arm. We suggest keeping the valve all the way open.
- Continue until the tank’s headspace oxygen is < 100 ppb, or until stable low DO readings are confirmed. For our testing tanks, a 7bbl brite was around 20 minutes, a 20bbl brite around 30 minutes, and a 40bbl brite around 45 minutes.
- By using this method, we have achieved DO readings after transfer to brite tank between 6 – 18 ppb, somewhat dependent on beer style and secondary additions.
Beer Transfer into the Brite Tank
- Purge Lines and Hoses: Flush product hoses and fittings with CO₂ prior to transfer.
- Closed Transfer Setup:
- Connect fermenter → brite with CO₂-flushed lines.
- Always fill the brite tank from the bottom port, avoiding turbulence and foaming.
- CIP Arm Venting During Transfer: Use the CIP arm as a controlled vent point instead of popping the PRV to the atmosphere. This prevents air ingress.
Post-Transfer Best Practices
- Keep steady CO₂ head pressure on the brite tank once full.
- Regularly inspect PRVs, CIP arm seals, and gaskets for leaks.
Additional Best Practices
- Change out gaskets (tri-clamps, manway, etc) on a schedule. Tri-clamp gaskets are inexpensive and easy to change when breaking down the tank
- Reminder that at average CO elevations, a 1 cm3 volume of air is the equivalent of 100 ppb of O2 in 1.7 BBLs of volume. Purge everything that you connect and make sure the space between fittings are purged of O2.
- Don’t forget to check smaller connection hoses on the CO2 line and keg lines – Oetiker clamps can become loose over time, allowing O2 to enter the transfer/carbonation line.
- Clean under pressure if you can! Always check after your cleaning procedure to see if O2 was introduced somewhere. https://coloradobeer.org/tech-safety-posts/cleaning-under-pressure/
