What fuel gases are most commonly used in blowtorches?

The correct choice identifies LPG, which includes both butane and propane, as well as natural gas, as the most commonly used fuel gases in blowtorches. These gases are favored for their properties that allow for effective and controlled combustion.

LPG, particularly propane, is widely accessible and burns cleanly, producing a high-temperature flame ideal for tasks such as welding, brazing, and soldering. Natural gas, consisting primarily of methane, is another common fuel utilized in blowtorches, especially in stationary applications linked to a natural gas supply.

The other fuel combinations are less practical for blowtorch applications. For example, while hydrogen can be used in certain specialized applications, it does not have the versatility and availability of LPG or natural gas. Helium, while useful in various high-temperature applications, does not provide the same combustion capabilities required for tasks that blowtorches typically perform. Similarly, carbon dioxide is a gas that is not combustive and therefore cannot be effective as a fuel gas in this context.