Scuba Diving International (SDI) Computer Nitrox Practice Exam

If a Nitrox blender analyzes the gas at 32 percent instead of the requested EAN30, what should you do?

1. Accept it, as it's within accuracy

2. Refuse the fill

3. Consult with a dive instructor

4. Ask the blender for a detailed explanation

The correct answer is: Refuse the fill

When a Nitrox blender analyzes the gas and produces an oxygen concentration that differs from the requested EAN30, it is important to consider safety and dive planning. Analyzed gas at 32 percent oxygen means the gas mixture is significantly richer in oxygen than EAN30, which contains only 30 percent oxygen. This can result in an increased risk of oxygen toxicity, especially at greater depths, as the partial pressure of oxygen can exceed safe limits for recreational diving. Refusing the fill is the most prudent course of action because safety should always be the top priority. The difference in oxygen percentage in this scenario could lead to dangerous circumstances during a dive. The blend must match specific percentages to ensure that divers operate within safe limits and minimize potential health risks. Accepting the fill might be considered if the variance was within an acceptable accuracy range; however, in this case, the difference in percentage indicates a substantial deviation that is not safe. Consulting a dive instructor or asking the blender for a detailed explanation may involve discussing the problem further but would not directly address the immediate safety issue at hand — which is vital when dealing with gas mixtures used for diving.