PADI Enriched Air Nitrox Diving 3

Question 1

A diver's nitrox computer shows a CNS clock at 75% after the first dive. What should concern the diver most before a second dive?

Accepted Answer

Accumulated CNS oxygen toxicity exposure nearing its limit

Answer

The CNS clock tracks cumulative oxygen toxicity exposure; diving again without adequate surface interval risks reaching 100% and potential toxicity symptoms.

Question 2

Why does enriched air nitrox reduce a diver's no-decompression limit (NDL) compared to air at the same depth?

Accepted Answer

It doesn't — nitrox extends NDLs by reducing nitrogen percentage

Answer

Nitrox contains less nitrogen than air, so tissues absorb nitrogen more slowly, resulting in longer NDLs for the same depth.

Question 3

What is the recommended PADI pO₂ limit for normal recreational enriched air diving?

Accepted Answer

1.4 ata

Answer

PADI recommends a maximum pO₂ of 1.4 ata for recreational diving, with 1.6 ata only acceptable in exceptional circumstances with close monitoring.

Question 4

A buddy team discovers one diver's cylinder is labeled EANx40 but was only analyzed at EANx36. What is the correct action?

Accepted Answer

Skip the dive and have the cylinder re-analyzed by a qualified technician

Answer

Any discrepancy between the label and analysis requires the cylinder to be re-checked by a qualified technician before it is safe to dive.

Question 5

Which factor does NOT affect the rate at which a diver accumulates CNS oxygen toxicity?

Accepted Answer

Water temperature

Answer

CNS toxicity accumulation is determined by the partial pressure of oxygen (a function of depth and mix fraction) and exposure time, not water temperature.

(PADI) Certified Professional Association of Diving Instructors Diver Practice Test

(PADI) Certified Professional Association of Diving Instructors Diver Practice Test

PADI Enriched Air Nitrox Diving 3