Ethyne, or acetylene (C2H2), is highly-popular as a fuel source for welding and metal-cutting.  This is because acetylene flame produces the highest temperatures, and it can easily be concentrated to a particular point to minimize wasted heat. As it also needs the least oxygen to combust properly, it is also the most efficient fuel for welding. An added benefit is that acetylene, like many hydrocarbon gases, is lighter than air; it accumulates far above the floor and away from any fires, reducing the likelihood that it will accidentally ignite. This makes the alkyne a safe, powerful and cost-saving fuel for any welding job.