Empire 20 oz CO2 Tank
The Empire CO2 tank is, like their HPA tanks, simply a Pure Energy tank with an Empire logo. A prospective buyer should know that all CO2 tanks run generally in the $10-$20 range and perform just about identically. They all have the same two-way valve design, one burst disc and are unregulated. I have had two Empire CO2 tanks and used each around twice. One continues to work perfectly but the second tank sprang a leak due to a faulty valve the second time I used it.
The problem with CO2 is that it is highly inconsistent especially in low temperatures and freezes the internals of a marker. How CO2 works is that it becomes a liquid at high pressures meaning that it is stored as a liquid in the tank. Some of the liquid becomes a gas and is used to shoot a marker. Every time a shot is fired, the pressure in the tank lowers allowing more liquid to evaporate and pressurize the tank. CO2 is therefore inherently bad for use in cooler temperatures when warm ambient temperature is not available to facilitate evaporation and when multiple shots are being fired rapidly as the first shot will be fired at full pressure but each shot afterwards will have significantly less pressure.
Being stored as a liquid means that the tank can be much thinner and constructed to much less stringent regulations as HPA tanks making it cheaper. While it may seem worth the price, the $15 spent on a CO2 tank is best saved and spent on at least a steel HPA tank.