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CO2 Cylinders - The Dangers of Heat Exposure to CO2 Cylinders

CO2 cylinders are considered full once the weight of the CO2 charge is equal to 68% of the weight of the total water capacity of the CO2 cylinder. This is due to the expansion characteristics of the CO2 charge and the dramatic effects temperatures has on CO2. As temperatures decrease, the CO2 charge shrinks; while when temperatures rise, the CO2 charge will greatly expand. Since the CO2 charge is limited to the capacity of the cylinder, these changes are measured as an increase or decrease in pressure.

Below are some examples between the pressure of the CO2 charge within a 20 lb. CO2 cylinder and the affects of exposures to increase temperatures.

    • A 20 lb. CO2 cylinder is filled with liquid CO2 by weight. At the time of the filling, the temperature of the charge was extremely cold, and the pressure is around 100 PSI
    • When a fully charged 20 lb. CO2 cylinder, 68% full by water capacity, warms up to room temperature (around 70° F), the pressure inside the cylinder increases from 100 PSI to 837 PSI.
      • If the same cylinder were to reach 87.9° F, the entire charge would become a gas, no matter the pressure. A fully charged CO2 cylinder at this temperature will develop an internal pressure of approximately 1100 PSI.
        • If this same cylinder were exposed to 120° F temperatures, the internal pressure would be reaching 2000 PSI. This is an internal pressure greater than the marked service pressure of the cylinder. This cylinder was properly filled, and not overfilled.
        • At 155° F, this same cylinder will reach a pressure around 3000 PSI. This pressure is great enough to activate the safety of the valve, venting the charge through the safety – possibly unexpected.


As shown in these examples, when the temperature of a fully charged (properly filled and not over-filled intentionally or accidentally) cylinder increases, the pressure of the CO2 inside increases. The temperature that the safety would activate at and vent the contents of the cylinder out is not that high. The temperature of 155° F could easily be obtained in many different environments, whether it be in a shed, vehicle on a hot day, restaurant kitchen, etc.

Unexpected venting of a cylinder through the safety can startle personnel, lead to accidents, property damages, and/or bodily harm. Coming into contact of the CO2 charge being vented out of a safety can lead to personal injury, including frostbite.

When using, handling, transporting, storing Co2 cylinders, always be aware of the temperature to which the cylinders are being exposed. This is not just the temperature that the cylinder is exposed to at the point in time, but also the maximum temperature that the cylinder will be exposed to at any point in time while the cylinder is in service.

It is recommended that CO2 cylinders not be used at temperature approaching and exceeding 120° F.

For more information regarding technical support documents on cylinders, please visit www.cganet.com.

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