What should be done if an EANx tank is inadvertently filled with air?

The appropriate action if an EANx tank is inadvertently filled with air is to avoid diving; the mixture is unsafe.

Enriched Air Nitrox (EANx) tanks are specifically filled with a higher percentage of oxygen, which has been tailored to optimize dive profiles and reduce nitrogen exposure. When a tank intended for EANx is filled with regular air, the composition changes significantly, leading to an unpredictable nitrogen and oxygen ratio that may create risks during diving. The increased nitrogen levels could lead to a higher risk of nitrogen narcosis and decompression sickness, particularly on deeper dives or prolonged exposure.

Consequently, diving with a tank that contains undesired air composition can greatly compromise safety and diver health, making it crucial to refrain from diving until the tank is corrected or properly configured back to its intended gas mix. Always ensuring the correct gas mixture is essential for safe diving practices.