CO2 chargers are small metal cylinders filled with liquid carbon dioxide under extremely high pressure. When the charger is pierced or opened, the liquid CO2 rapidly expands into a gas. This expansion process is what drives the charger's function.  

Here’s a breakdown of how it works:

• Pressurized liquid CO2:The gas is compressed into a liquid state and stored within the charger.
• Piercing or opening:When you use a CO2 inflator or another device to pierce or open the charger, the high pressure forces the liquid CO2 to escape rapidly.
• Expansion into gas:As the liquid CO2 escapes, it undergoes a dramatic expansion, transforming into a gas. This rapid expansion creates a significant increase in volume.
• Gas utilization: The expanding gas is then channeled through the device, performing its intended function. For example, in a bike tire inflator, the gas fills the tire; in a soda siphon, it carbonates the water.

The key to the CO2 charger's effectiveness is the rapid expansion of the liquid CO2 into gas. This process provides the necessary force to inflate tires, carbonated beverages, or perform other tasks.