Carbon dioxide, or CO2, is used in a wide spectrum of modern technologies because of its physical properties. CO2 can be purchased in compressed form in CO2 tanks, for larger applications, and in smaller compressed CO2 cartridge form. There are a number of commercially available CO2 cartridges on the market. These cartridges come in a wide selection of sizes, shapes, nozzle sizes and qualities, and they can be used for a number of applications.
One of the most common uses for commercially available CO2 cartridges is in projectile weapons. A number of paintball guns utilise CO2 cartridges for propulsion, as do most Airsoft guns and a number of air rifles. Paintball guns and larger air rifles/Airsoft guns with automatic fire capability typically use larger gas cartridges, or even small compression tanks, to store the CO2. Smaller CO2-powered Airsoft weapons often use smaller cartridges. CO2 powered guns typically contain an internal gas tank, which is used to store the compressed CO2 from the cartridge that has been used to "charge" the weapon. The internal tank then releases short but powerful bursts of CO2, which are used to propel small metal or plastic pellets (or paintballs) through the barrel of the gun.
Bicycle Inner Tubes
CO2 cartridges can also be used to temporarily inflate bicycle tires. This is useful for emergency applications, such as a popped tire, and takes a fraction of the time required to reinflate an inner tube with a hand pump. To use cartridges in this manner, you need a specialised inflation tool. These tools come with optional flow control for ease of use, and can fit a number of different sized CO2 cartridges, both threaded and unthreaded. Using the inflator, a cyclist can easily pop in a cartridge, attach the inflator to the tyre's inner tube, and have the tube inflated in just seconds. However, CO2 is not useful for long-term inflation, as the gas can dissipate through the rubber, leaving a flat inner tube after a few days. This limits the use of CO2 cartridges for cyclists to temporary or emergency applications.
CO2 cartridges can be used to propel homemade miniature cars along a straight track. This activity is sometimes organised in racing competitions, and is often used by teachers to demonstrate the laws of aerodynamics and momentum. Typically, the participants each design a car within a set of limitations, and each car includes a rear compartment or space to hold the CO2 cartridge. The cars are then placed on a straight track with some form of guide rail, and the CO2 cartridges are simultaneously released, propelling the cars forward at the same time.
One famous application of carbon dioxide is in the creation of carbonated drinks. This can be done at home with CO2 cartridges in a number of ways. Beer brewing enthusiasts often carbonate their homebrews by using a CO2 cartridge to keep the keg under pressure. After a sufficient amount of time has passed, the beer will be thoroughly carbonated. There are also a number of ways in which CO2 cartridges can be used in conjunction with a soda fountain to instantly carbonate beverages while serving them. For example, an improvised fountain could carbonate water or juices while serving them. Yet another way of carbonating beverages is by using a specialised bottle designed to fit the smaller food-grade CO2 cartridges, sometimes called "seltzer chargers." These are a simple and easy way of carbonating drinks using CO2 cartridges.