This is a real plot from a real tank. It’s useful precisely because it went wrong.
What the plot showed
The head pressure when carbonation started was already 7 PSI. It should have been close to zero.
Why that matters
Head pressure is only a proxy for carbonation level if you start from a known baseline. At 7 PSI, the head pressure in the bright tank is not representative of the carbonation level. The tank will still build pressure and the beer will still pick up some CO2, but it will finish undercarbonated: the pressure rise the controller sees isn’t the rise the beer actually got.
The secondary problem: a closed CIP arm
At the start of this run, the CIP arm wasn’t open. Had that persisted for half an hour or more with leak detect enabled (one of FizzWizz’s alert functions), the system would have emailed the brewer automatically. This brewer didn’t have leak detect on, so nobody knew until the beer tasted flat.
The knock-on effects
- The flow rate was nice and slow, so flow wasn’t the problem: the starting baseline was.
- The run dragged on until about 2 a.m. instead of finishing around 6 to 7 a.m. as it would have from a zero baseline.
- The beer was tested and tasted undercarbonated.
- The brewer bumped the target from 3.0 to 3.3 volumes and ran another couple of hours. Our read: the beer was still likely undercarbonated when it finished, because the starting pressure problem was never fixed.
The takeaways
- Start from zero. Before a carbonation run, confirm the tank head pressure is at baseline. If it isn’t, find out why before pressing go.
- Open the CIP arm before you start. This run began with it closed, and nothing flagged it.
- Turn on leak detect. If the CIP arm stays closed for half an hour or more, leak detect emails you, so you don’t find out by tasting flat beer the next day.
Plots look wrong and you can’t see why? Our support team regularly reviews customer plots. Send us yours and we’ll take a look. Contact support.