Exam Focus
- Explain how temperature, applied pressure, and gas blend maintain the brewer's intended carbonation level.
- Measure liquid beer temperature at the keg and faucet when troubleshooting foam.
- Distinguish carbonation-maintenance pressure from pressure used only to move beer through a system.
Carbonation maintenance
Applied carbon dioxide pressure should preserve the carbonation already in the beer. The correct setting depends on beer temperature, desired carbonation, altitude, and gas blend, so pressure changes should be made from a carbonation target rather than from foam symptoms alone.
Start with measured temperature
Foam troubleshooting should begin with liquid beer temperature. A keg may be cold while beer warms in a tower, trunk, wall penetration, or faucet. Measure beer in the glass and compare it with cooler and system targets before changing applied pressure.
Why pressure changes can make things worse
Raising or lowering pressure to chase flow can overcarbonate or undercarbonate beer over time. Once carbonation drifts, the draft problem becomes harder to solve than the original temperature, restriction, or gas-blend issue.
Key Terms
- System balance
- Matching applied pressure to total restriction so beer pours at the intended flow rate while maintaining carbonation.
- Gas blend
- A dispense gas mixture used to provide enough push pressure while controlling carbon dioxide partial pressure.