CO2 cartridges are small, sealed metal containers that hold pressurized carbon dioxide, used widely in products like bicycle tire inflators, soda makers, and airguns. While these cylinders are robust, the stored substance contains significant potential energy. A true combustion-based explosion is nearly impossible, but a violent rupture can occur under specific, preventable conditions.
How Pressurized CO2 is Stored
Carbon dioxide is stored inside the cartridge in a unique two-phase state, primarily as a liquid with a gas vapor layer above it. The CO2 is liquefied under high pressure, allowing a substantial amount of gas to be condensed into a minimal space. At a standard room temperature of 70°F (21°C), the internal pressure of a full cartridge sits between 800 and 950 pounds per square inch (PSI).
The internal pressure is directly linked to the temperature of the liquid CO2 within the cylinder. As long as liquid is present, the gas vapor pressure remains relatively constant for a given temperature. Cartridges include a structural safeguard, often a thin metal seal or burst disk, intended to fail safely before the cylinder wall fractures. This feature rapidly vents the gas if the internal pressure exceeds the maximum design limit, which is often over 2,000 PSI.
External Factors Causing Failure
The most common cause of cartridge failure is exposure to extreme heat, which directly affects the internal pressure. If a cartridge is subjected to high temperatures, such as being left inside a closed car or near a heat source, the internal pressure climbs rapidly. Because the relationship between temperature and pressure is steep for CO2, the internal pressure can quickly exceed the container’s structural integrity.
Manufacturers recommend that cartridges not be exposed to temperatures exceeding 122°F (50°C). When this limit is surpassed, increasing heat causes the internal pressure to approach the failure point of the shell or the burst disk. Physical damage also compromises integrity. Dents, corrosion, or deep scratches create weak points that fail at pressures far below the intended maximum.
Rupture Versus Explosion
The distinction between a rupture and an explosion clarifies the risk profile of CO2 cartridges. Carbon dioxide is a non-flammable gas, used in fire extinguishers to suppress combustion. Therefore, a true chemical explosion involving a rapid, self-sustaining combustion reaction is not possible.
The failure event that can occur is a rapid, physical rupture of the pressure vessel. This happens when the container’s structural limit is exceeded, causing the metal to tear or the pressure-relief seal to fail instantaneously. When the pressurized gas is released violently, it generates a loud noise and a rapid expansion of energy, which is often described colloquially as an explosion. The primary danger in this scenario is the potential for cartridge fragments to be propelled outward with significant force, or for the entire cartridge to become a fast-moving projectile.
Essential Safety and Storage Guidelines
Preventative measures focus on controlling the two major factors that lead to failure: temperature and physical damage. Cartridges should always be stored in a stable environment well below the manufacturer’s maximum recommended limit. This means avoiding storage in direct sunlight, near furnaces, or inside vehicles during warm weather.
Before use, every cartridge should be visually inspected for signs of physical compromise, such as rust, deep scratches, or deformation to the metal shell. Users should never attempt to tamper with, modify, or refill spent cartridges, as this alters the container’s engineered safety tolerances. For disposal, cartridges must be confirmed as completely empty before being recycled or discarded in accordance with local regulations.