Beverage CO2 Cylinder Duration

CO2 leaves the cylinder two ways: it pushes beer out of the keg, and it stays dissolved in the beer that leaves. Both scale with volume dispensed, which is why a two-tap bar and a twelve-tap bar pouring the same number of kegs a year use the same gas. Direct-draw systems at 12 to 14 psi run near one pound of CO2 per half barrel; a long-draw system pushing 30 to 40 psi through a glycol trunk uses considerably more, and blended gas changes the arithmetic again. A 20 lb cylinder on a direct-draw system at 1.2 lb per keg carries 20 / 1.2 = 16.7 kegs, and a bar pouring 2 kegs a day gets 8.3 days out of it. The practical output is the change-out point, because a cylinder run to empty goes flat mid-pour and the regulator loses pressure without warning, so a 20% reserve puts the swap at 13.3 kegs, about 6.7 days. That makes a single 20 lb cylinder a weekly item and the bar needs a second one on the wall, not a phone call. Push the same bar to a long-draw system at 1.5 lb per keg and the cylinder drops to 13.3 kegs: the system design, not the volume, moved the delivery schedule. An operating estimate; a cylinder scale and the gas supplier's measured consumption govern.

kegs_per_cylinder = cylinder_lb / lb_co2_per_keg; days_of_supply = kegs_per_cylinder / kegs_per_day; changeout_kegs = kegs_per_cylinder x (1 - reserve_fraction); changeout_days = changeout_kegs / kegs_per_day.

Per-keg gas consumption of a draft system from public draft-beer engineering practice, for which the Brewers Association Draught Beer Quality Manual is the standard reference, by name; a cylinder scale and the gas supplier's measured consumption govern.

The duration arithmetic is division on the bar's own numbers: cylinder weight, pounds of CO2 per keg for the system type, kegs dispensed per day, and the reserve the operator wants.

Estimate. AHJ and licensed professional govern.

Field names used by the API: cylinder_lb, lb_co2_per_keg, kegs_per_day, reserve_fraction, kegs_per_cylinder, days_of_supply, changeout_kegs, changeout_days

• Per-keg consumption near 1 lb per half barrel direct-draw at 12 to 14 psi; considerably more on a long-draw system at 30 to 40 psiBrewers Association Draught Beer Quality Manual
• Reserve a cylinder run to empty loses regulator pressure without warning, so the change-out is set short of the theoretical endbar operations practice
• Scales with volume consumption tracks the volume dispensed, not the number of tapsdraft-beer engineering practice