Carbon dioxide (\(\text{CO}_2\)) cartridges are common, compact cylinders used for various applications, from inflating bicycle tires and powering airsoft guns to carbonating beverages. Because these containers hold gas under high pressure, understanding the risks associated with temperature exposure is important for safety. The term “explosion” usually refers to a violent burst, but in the context of a \(\text{CO}_2\) cartridge, the failure mechanism is typically a controlled rupture designed to prevent such a dangerous outcome. This pressure release, though loud and forceful, is the intended safety response when the internal conditions exceed the cylinder’s design limits.
The Inner Workings of a CO2 Cartridge
A \(\text{CO}_2\) cartridge operates based on the unique phase properties of carbon dioxide. The gas is stored under pressure primarily as a liquid, which allows manufacturers to pack a significant amount of \(\text{CO}_2\) into a small container. This equilibrium of coexisting liquid and gas phases is what generates the high internal pressure at room temperature. The internal pressure of the cylinder is directly governed by the temperature of the liquid \(\text{CO}_2\) inside, known as the vapor pressure.
As the surrounding temperature rises, more of the liquid \(\text{CO}_2\) quickly converts into gas, which dramatically increases the pressure within the fixed volume of the cartridge. This relationship holds true until the carbon dioxide reaches its critical temperature of \(87.9^{\circ}\text{F}\) (\(31.1^{\circ}\text{C}\)). Above this temperature, the \(\text{CO}_2\) exists as a supercritical fluid, a dense gas that continues to experience rapid pressure increases with any further rise in temperature.
Defining the Critical Temperature Threshold
The temperature at which a \(\text{CO}_2\) cartridge fails is not a single fixed number but a range determined by manufacturer specifications and the cylinder’s built-in safety features. Most manufacturers specify a maximum safe handling and storage temperature, often \(120^{\circ}\text{F}\) (\(49^{\circ}\text{C}\)). Exceeding this temperature significantly raises the internal pressure closer to the structural limits of the cylinder material.
The true failure point, where the safety mechanism yields, is usually higher. In a properly filled and manufactured cylinder, the pressure typically reaches a point that triggers the safety device around \(150^{\circ}\text{F}\) (\(65.6^{\circ}\text{C}\)). This pressure is substantial, often exceeding 2,600 pounds per square inch (psi).
Instead of a violent explosion, most modern \(\text{CO}_2\) cylinders are equipped with a rupture disc or burst disc. This safety mechanism is a thin component designed to fail at a specific, pre-determined pressure, such as between 2,800 and 3,000 psi for larger tanks. When the internal pressure hits this set limit, the disc ruptures, allowing the gas to vent forcefully but controllably, preventing a catastrophic structural failure of the cylinder wall.
Scenarios Leading to Cartridge Failure
The temperatures required to trigger a cartridge failure are easily reached in common environments. Any situation that exposes the cartridge to direct, concentrated heat or high ambient temperatures presents a risk of over-pressurization. Leaving cartridges in direct sunlight is a common cause, as the dark metal surface absorbs solar radiation and heats up quickly.
A particularly hazardous scenario involves storing cartridges inside a closed vehicle during warm weather. Even on a mild day, the temperature inside a parked car can rapidly climb well above \(120^{\circ}\text{F}\). This greenhouse effect can quickly push the internal pressure past the safety limit, leading to the rupture disc venting.
Placing a cartridge near a direct heat source, such as a furnace, water heater, or heating vent, creates a risk of thermal runaway. While ambient heat causes a slower, gradual pressure increase, direct exposure to a flame or a stovetop element can cause an instantaneous and dangerous pressure spike. The temperature of the metal casing, not just the ambient air temperature, dictates the internal pressure of the \(\text{CO}_2\).
Safe Handling and Storage
Minimizing the risk of thermal failure requires adherence to practical storage guidelines centered on temperature control. The core recommendation is to store all \(\text{CO}_2\) cartridges in a cool, dry, and well-ventilated area. Storing them in a climate-controlled space, such as a garage or basement that remains below \(70^{\circ}\text{F}\), provides a substantial safety buffer.
It is important to secure the cartridges to prevent them from rolling or falling, which could damage the valve or the cylinder body. Never store cartridges in locations that receive direct sunlight. Furthermore, avoid keeping them in any vehicle, as temperatures inside can quickly become unsafe during sunny or warm conditions.
Always follow the manufacturer’s maximum specified temperature, which is often \(120^{\circ}\text{F}\), and treat this as a firm upper limit. If a cartridge has been damaged, is visibly rusted, or has been exposed to extreme heat, it should be disposed of properly according to local regulations, rather than risking use or continued storage.