Technology · FAQ
Carbonation and CO2 FAQ
Carbonation is the physics that makes CSD a different machine category: gas dissolves in cold liquid under pressure, and it must stay dissolved through filling. This FAQ explains the principles in plain engineering terms — the ones that decide the filler, the gas plant and the running cost.
CO₂
The universal carbonation gas
444+
Líneas entregadas
71+
Países exportadores
20,000
m² workshop
2011
Se fundó Sunswell
Respuesta corta: CO2 dissolves better in cold liquid under pressure, which is why CSD lines cool the product, carbonate it in a pressure vessel, and fill it with an isobaric counter-pressure valve that equalises the bottle before it opens. Gas losses happen at every stage — filling, purging, storage — and they are a running cost, so the gas plant and the filler design decide how much fizz you keep and how much you pay for.
🎯 Conclusiones clave
- CO2 solubility rises as temperature falls and pressure rises — cooling before carbonation is not optional.
- Isobaric counter-pressure filling keeps the gas in solution by pressurising the bottle first.
- Gas losses at filling and storage are a real running cost — the design decides them.
- Bulk CO2 storage beats cylinders at volume, with a site-specific layout.
- Specify the carbonation level and the product temperature — they set the gas plant.
En esta página
1. The physics in one paragraph
CO2 is a gas that dissolves into liquid, and the amount that stays dissolved follows two rules: colder liquid holds more gas, and higher pressure holds more gas. Warm the drink or drop the pressure and the gas comes out of solution as bubbles — which is foam at the filler and lost fizz in the bottle. Every machine in a CSD line exists to keep the drink cold and pressurised until it is sealed.
That single paragraph explains the cooler, the carbonator, the isobaric filler and the capper. The rest is engineering detail.
2. The carbonation plant
The carbonation plant is a pressure vessel where chilled, deaerated product meets CO2 under controlled pressure, reaching the target gas volume. It is fed by the water/syrup skid and feeds the filler. The design points are the product temperature, the pressure, and the residence time — set by the recipe's gas-volume target.
Under-sizing the carbonator starves the filler at rated output; over-sizing wastes money. Size it on the recipe and the line output, with the product temperature stated.
3. Why filling must be counter-pressure
If a carbonated drink is filled into a bottle at atmospheric pressure, the pressure drop makes the gas come out of solution instantly — foam, fizz loss, underfilled bottles. The isobaric filler pressurises the bottle with CO2 to the tank pressure before the valve opens, so the drink enters a bottle at equilibrium and the gas stays in solution.
Counter-pressure filling is not a choice for carbonated product — it is the only way to fill without losing the gas. A gravity filler cannot run CSD.
The capper then seals the bottle before any pressure release, and the bottle's internal pressure is part of its design spec.
4. Where gas is lost
Gas is lost at the filler (purging and venting), in storage (pressure venting), and in the process (dissolved gas in waste streams). The losses are a running cost — CO2 is bought, not free — and the design decides how much leaks. Recovered or recycled gas systems exist for large plants, with payback that depends on gas price and volume.
Ask the supplier for the expected gas consumption per thousand bottles at your recipe. The honest answer is a spec number, and it belongs in the proposal.
5. CO2 storage and supply
CO2 arrives as bulk liquid in a pressure tank or as cylinders. Bulk storage suits volume production and lowers the per-unit gas price; cylinders suit small plants and simple logistics. The choice is a site decision: space, local supply, delivery frequency and safety permitting.
Plan the storage location with the layout — the gas line to the carbonator should be short and safe, and the local supplier's delivery schedule should match your consumption.
6. Fizz quality and consistency
Consistent fizz means consistent gas volume, bottle after bottle: the recipe target, the temperature control and the filler's counter-pressure behaviour all have to hold. Temperature drift is the usual culprit for inconsistent carbonation — a cooler that cannot hold the product temperature makes the gas plant chase a moving target.
Quality also means the right CO2 grade and clean product path: impurities and oxygen in the water degrade both taste and gas retention, which is why deaeration sits before carbonation.
7. What to specify
To spec the gas side you need four numbers: the gas-volume target for the recipe, the product temperature at filling, the line output, and the bottle (which sets the counter-pressure behaviour). Send these to the supplier and the proposal will include the carbonator, the cooler, the gas plant and the expected consumption.
The whole gas side lives upstream of the máquina de llenado de refrescos carbonatados and is engineered with it as one system — ask for a combined proposal, not two separate quotes.
Preguntas frecuentes
Why is the drink cooled before carbonation?
CO2 dissolves better in cold liquid. Cooling first lets the carbonator reach the target gas volume at a workable pressure, and it controls foam at the filler.
Can a gravity filler run carbonated drinks?
No. Carbonated product must be filled under counter-pressure, or the pressure drop releases the gas as foam. Isobaric filling is a requirement.
Where does CO2 go in production?
It is consumed into the drink, and some is lost at filling, purging and storage. Losses are a running cost — the design decides how much.
Bulk tank or cylinders?
Bulk liquid storage lowers the per-unit price at volume; cylinders suit small plants. The choice depends on consumption, space and local supply.
What causes inconsistent fizz?
Temperature drift is the usual cause. If the cooler cannot hold the product temperature, the gas volume varies bottle to bottle.
Does Sunswell supply the carbonation side?
Yes — Sunswell supplies complete CSD lines including water treatment, deaeration, cooling, carbonation and isobaric filling as one system.
Acerca del autor.
Escrito por el equipo de ingeniería de Sunswell, liderado por Howie solFundador y director ejecutivo, con 14 años de experiencia en I+D de equipos de llenado y moldeo por soplado, y en la entrega de proyectos llave en mano en más de 71 países.
Última revisión: 28/08/2026 · Revisado por el equipo de ingeniería de Sunswell
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