What could happen if copper is used instead of a brass hose splice?

Using copper instead of a brass hose splice introduces significant risks, particularly with the formation of copper acetylene under certain conditions. When copper is used in the presence of acetylene—especially under pressure or heat—it can react to form a highly explosive compound. This is a critical concern in welding and gas handling environments where acetylene is employed as a fuel gas.

Brass, on the other hand, is an alloy that typically consists of copper and zinc, designed for strength, durability, and chemical resistance, particularly against the kinds of reactions that could lead to dangerous conditions. While copper itself is a strong material, its reaction with acetylene poses a far greater hazard than any advantages it might have in terms of strength or rigidity.

The other options present potential issues as well, but they do not encompass the immediate and serious explosive danger that copper acetylene formation represents. The emphasis on explosive hazards makes the use of copper in lieu of brass particularly inappropriate in applications involving gases like acetylene.