CO₂ for a brewery and a bottling line: how much you need and of what purity

Carbonation is only a third of the CO₂ a brewery uses. Consumption per hectolitre, where the rest disappears, the purity the product demands, and how to size the tank and vaporizer.

Ask a brewer how much CO₂ the plant uses and the answer usually starts with carbonation. Carbonation is the smallest part of it. Most of the gas goes on purging, counter-pressure filling and transfers — and that is also where it is easiest to lose.

Where the CO₂ actually goes

Every one of those touches the product or its headspace. That is why the whole plant runs on food-grade CO₂: there is no such thing as «technical gas for purging only» in a beverage line — the purge gas ends up in contact with the beer.

How much per hectolitre

A well-run plant with recovery uses 0.5–1.5 kg of CO₂ per hectolitre of finished product. A craft brewery without recovery, with frequent small batches and manual transfers, spends 2–4 kg per hectolitre. The gap is not technology — it is the number of purges per litre packaged.

For a plant packaging 8 000 hl a month, a 30 m³ tank holds about 29 tonnes — roughly two months of supply at the efficient rate, or one full road tanker delivery with reserve. That is the ratio worth aiming at: one delivery must fit, and turnover must stay fast enough that boil-off does not eat the margin.

Purity: what «food grade» has to mean

The reference documents are the ISBT quality guidelines for beverage-grade carbon dioxide and the EIGA specification. They limit not only total purity but individual contaminants — moisture, oxygen, total hydrocarbons, sulphur compounds, acetaldehyde, benzene. A single number like «99.9%» says nothing on its own, because the compounds that ruin taste act at parts-per-million level. We covered the parameter list in a separate article on ISBT and EIGA requirements.

A supplier certificate covers the batch as it left the filling plant, not what arrived in your tank after a tanker that previously carried something else. A minimum incoming inspection kit — moisture, oxygen, a sensory check — pays for itself the first time it stops a bad batch before it reaches a fermenter.

Sizing the vaporizer, not just the tank

Brewery demand is bursty. A filling line starting up, a tank being purged and a transfer running at the same time can triple the average draw for twenty minutes. Size the vaporizer for that peak: a 300 kg/h unit suits most mid-size plants, while a large bottling operation with several lines needs 1000 kg/h.

• Measure the peak, not the monthly average divided by hours.
• Remember that an ambient vaporizer loses capacity in frost and needs a standby unit or a switchover pair.
• Keep pressure regulation close to the point of use — a long run from the tank costs you pressure exactly when demand spikes.