Carbon dioxide: Characteristics
Why benzene traces can ruin a soft drink
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.Purity and trace impurities matter most. Beverage-grade CO2 must be at least 99.9% with ppm limits on sulphur, benzene and acetaldehyde, because off-flavours ruin products. CO2 has no liquid phase at atmospheric pressure: it is stored as liquid under pressure or as solid dry ice at -78.5 C.
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Purity (beverage grade) | at least 99.9% with ppm limits on impurities (ISBT) | taste and safety in drinks | ISBT guidelines (indicative) |
| Storage condition | liquid at about -20 C and 20 bar | sets tank and tanker design | industry practice (indicative) |
| Sublimation point | -78.5 C (dry ice) | cold chain and food chilling | physical data |
| Density of gas | 1.98 kg per m3 at 0 C | heavier than air; asphyxiation risk | physical data |
Commercial grades
- Beverage/food grade (E290)
- Industrial grade
- Medical grade
- EOR/CCS grade (pipeline spec)
- Dry ice