Properly using a spunding valve can be a game-changer for many breweries looking to improve carbonation consistency, reduce CO2 costs, and capture fresher flavors.
Whether you’re adopting them for the first time or refining your process — gaining insights from Sean Garvin, assistant Brewmaster at Deschutes, and Peter Batinski, the head of the specialty and sour program at Hi-Wire — proper spunding valve use is about balancing pressure application, understanding fermentation timing, and closely monitoring batch variables.
These strategies can translate into cost savings, better flavor stability, and more consistent carbonation across brands.
“More work and possible opportunities may exist for us within a spunding philosophy and practice,” Garvin said.
Spunding valves allow brewers to capture natural carbonation from fermentation by sealing the vessel and setting a desired pressure. For many breweries, this means less CO2 is needed later for carbonation, improved flavor retention, and better foam stability.
“We use spunding valves at Hi-Wire Hilliard for retention of aromatic compounds and increased head retention,” Batinski said. “Yes, we get a carbonated beverage faster, but this isn’t the main reason we use them.”
At Deschutes, the approach varies depending on the brand and cellar setup.
“We have referred to this process as ‘bunging’ with differing end goals depending on the required process coming out of fermentation,” Garvin said.
While Hi-Wire uses spunding valves for natural carbonation capture, Deschutes applies mild back pressure during diacetyl rest for yeast management and to prepare for dry hop additions — not as a method to reach final carbonation levels.
Both breweries emphasize that timing is critical when introducing pressure to fermentation vessels. Deschutes applies a variable pressure relief valve (PRV) at the transition from free rise to diacetyl rest, typically when the apparent degree of fermentation (ADF) reaches between 76% and 86%.
“For our Lager example, the transition following free rise to diacetyl rest occurs at 76% ADF (~3.5 Plato), and we currently are at 2.5 PSI set point here as well for yeast handling reasons,” Garvin said.
This gradual increase from 0.5 PSI to 2.5 PSI takes about eight hours.
Hi-Wire’s approach is less automated but equally methodical. Batinski determined the ideal spunding pressure through incremental testing.
“It’s been a very long time, but I would attach the valve, and each subsequent batch I would increase the pressure slightly,” he said. “I have found that at my brewery, 10-12 PSI works across all brands when the beer is ready to be spunded.”
Initial pressures should be low to avoid yeast stress, then increased gradually. Deschutes begins with 0.5 PSI during active fermentation before rising to 2.5 PSI at diacetyl rest. Hi-Wire targets 10-12 PSI once primary fermentation slows.
Batinski cautioned that spunding pressure isn’t just about CO2 volumes. Consistency has dramatically improved across all brands by standardizing pressures, he said.
As fermentation nears completion and maturation begins, breweries should monitor both pressure and residual extract drop. Deschutes typically sees a further Plato drop of 0.1 to 0.15 and CO2 volumes approaching 2.0 vols.
Following a diacetyl rest and cooling, Deschutes transitions to forced CO2 to finish carbonation.
“Our automated vessel header matrix changes mode to CO2 supply, with a bump in pressure set point to 10 PSI,” Garvin said.
Clarification is completed with in-line carbonation to meet packaging specifications.
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One of the clearest benefits of spunding valves is the reduction in external CO2 usage.
“If my math is correct, we are using about 60% less CO2 when a spunding valve is attached to carbonate beer,” Batinski said.
While Garvin noted that Deschutes sees “opportunity in this realm for general CO2 savings,” both breweries agree the practice supports operational efficiency and sustainability goals.
For those hesitant about complexity, Batinski assures brewers that installation is straightforward. “Not at all, they are very simple to attach and use as desired,” he said of the setup.
Maintaining positive pressure also helps minimize oxygen ingress — a critical factor in beer stability.
“It can be easily assumed that with positive pressure, you have less chance of exposure to oxygen,” Batinski said.
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