Enriched Air Nitrox Diving Flashcards

What is the primary reason enriched air nitrox divers must analyze their tank before diving?

Answer: To verify the actual oxygen percentage matches the planned mix

Tanks must be analyzed to confirm the oxygen fraction matches the mix you plan to dive, since an incorrect mix changes MOD and CNS limits.

A diver plans to use EANx36 at 80 feet. What is the partial pressure of oxygen at that depth?

Answer: 1.26 ata

At 80 feet the absolute pressure is 3.5 ata; 0.36 × 3.5 = 1.26 ata pO₂.

Why must enriched air cylinders be marked with a distinctive yellow-and-green band?

Answer: To prevent a diver from accidentally breathing a mix beyond their training

The distinctive band is a visual warning that alerts the diver and others to the enriched oxygen content, preventing accidental use by untrained individuals.

Which body system is most directly stressed by oxygen toxicity during enriched air diving?

Answer: Central nervous system

CNS oxygen toxicity is the primary concern for divers because it can cause convulsions at high pO₂ levels, leading to drowning.

A diver using EANx32 wants to stay within a 1.4 ata pO₂ limit. What is the maximum operating depth?

Answer: 111 feet

MOD = (pO₂ limit / FO₂ − 1) × 33 = (1.4 / 0.32 − 1) × 33 ≈ 111 feet in seawater.

What does the term 'equivalent air depth' (EAD) allow a nitrox diver to do?

Answer: Use standard air dive tables to plan decompression stops

EAD converts a nitrox dive to the equivalent nitrogen exposure on air, letting divers use standard air tables or computers set to air.

When filling an enriched air cylinder, why is it important to dedicate or thoroughly clean equipment before use with oxygen-enriched mixes?

Answer: Oxygen reacts with residual hydrocarbons and can ignite or explode

Oxygen under pressure reacts violently with hydrocarbons such as oils and greases, creating a fire or explosion hazard if equipment is not oxygen-clean.