For complete combustion during oxyacetylene welding, a ratio of _________ parts oxygen to one part acetylene is required.

For complete combustion during oxyacetylene welding, a ratio of _________ parts oxygen to one part acetylene is required.

• A. 2:1
• B. 1:1
• C. 3:1
• D. 4:1

Answer: (A)

The main idea here is the oxygen-to-fuel balance needed for complete combustion of acetylene in an oxyacetylene flame. When acetylene burns completely, all the fuel reacts with oxygen to form carbon dioxide and water. The balanced chemical equation shows that one molecule of acetylene requires 5/2 molecules of oxygen, which is 2.5 parts oxygen per part acetylene. In other words, the stoichiometric ratio is about 2.5:1, so you’d aim for roughly 2.5 parts oxygen for every part acetylene to achieve complete combustion. Among the given options, the closest practical match is 2:1. That’s why it’s chosen as the correct answer. In real welding, you adjust toward the stoichiometric ratio to obtain a neutral flame, ensuring complete combustion without excess fuel (carburizing flame) or excess oxygen (oxidizing flame).

The main idea here is the oxygen-to-fuel balance needed for complete combustion of acetylene in an oxyacetylene flame. When acetylene burns completely, all the fuel reacts with oxygen to form carbon dioxide and water. The balanced chemical equation shows that one molecule of acetylene requires 5/2 molecules of oxygen, which is 2.5 parts oxygen per part acetylene. In other words, the stoichiometric ratio is about 2.5:1, so you’d aim for roughly 2.5 parts oxygen for every part acetylene to achieve complete combustion.

Among the given options, the closest practical match is 2:1. That’s why it’s chosen as the correct answer. In real welding, you adjust toward the stoichiometric ratio to obtain a neutral flame, ensuring complete combustion without excess fuel (carburizing flame) or excess oxygen (oxidizing flame).