What is the common designation for 40% oxygen content in Enriched Air Nitrox?

The designation for 40% oxygen content in Enriched Air Nitrox is commonly referred to as "EANx 40." The "EAN" stands for Enriched Air Nitrox, and the "x" represents the variable percentage of oxygen in the mixture. The specific designation "40" indicates that this particular mixture contains 40% oxygen and, therefore, 60% nitrogen. This terminology is widely accepted in the diving community as it clearly distinguishes the oxygen content while allowing for variations in the gas mixtures used for diving purposes. Using "EANx" is particularly beneficial because it accommodates other enriched air nitrox mixtures, such as EAN 32 and EAN 36, making it a flexible way to discuss different oxygen levels.

In contrast, while "EAN 40" may seem acceptable, it is less commonly used, and "Nitrox 40" does not provide the necessary clarity about the enriched air designation. "Oxygen 40" incorrectly implies that the gas mixture consists solely of oxygen, which could lead to confusion in diving applications. Therefore, "EANx 40" is the most accurate and widely recognized designation for this 40% oxygen content in Enriched Air Nitrox.