Although both may be a potential risk, Central Nervous System Oxygen Toxicity is the more apparent one for divers using hyperoxic mixes as this type will only occur at depth.

We track our daily exposure while diving with hyperoxic mixes, such as diving on recreational Nitrox or completing planned decompression procedures while Technical Diving, as the second type relative to divers, is Pulmonary Toxicity. This occurs when a person is exposed to increased pressures of Oxygen for extended periods of time.

Grab your calculators, kids. It's time for Dalton's triangle!

We have the information we need to answer the question, we just need to put it in the right order.

We have the PO2 max we are limiting the dive too so we need to divide that by the FO2 in the breathing mix, this is 1.4/0.32=4.375.

4.375 is the absolute pressure the breathing gas would need to be breathed at to reach the PO2. If we divide this by the pressure per metre in fresh water which 0.097ATM/m minus the 1 ATM exterted at the surface, 4.375-1=3.375. Then 3.375/0.097=34.79 (rounded to 2 decimal places)

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Mali’s PADI Open Water Diver students, Christina and Bert loved their course and would like to continue their education.

After talking about the PADI Advanced Open Water Diver course they realise they won’t have the time to complete the whole course so Mali explains the PADI Adventure Diver option and how PADI Adventure Dives work.

Their goal is to become PADI Advanced Open Water certified as they would one day like to become PADI Divemasters. After discussing their options with Mali they opt to complete their Deep Diver, Underwater Navigator and Peak Performance Buoyancy Adventure with Mali but not certify as PADI Adventure Divers as they plan to take a referral to their local dive centre and complete their Dry Suit and Night Diver Adventure Dives when they return home after this trip.

What does Mali need to do before beginning this program and is she within PADI standards?

“Mali would need to complete the PADI Continuing Education Administrative Document as it is required for any component of the PADI Advanced Open Water Diver course.

She also needs to issue each student the PADI Advanced Open Water Diver student manual too. Even though the students are not completing the entire program, PADI standards dictate that the student must have a personal copy of the materials both during the course and for their use afterwards.

Even though Christina and Bert would qualify for the PADI Adventure Diver certification after the completion of the dives and required knowledge development, their choice to take the referral option is a wise one. This reduces their costs as they will not need to certify for two separate programs.

There is also no time limit set on this referral either in accordance to PADI standards which states the exception for PADI Advanced Open Water Diver and PADI Specialty Diver courses from the standard 12 months after the last completed section of training.”

Gaz Lyden. 

The Con Ed Admin Doc, for short, covers the students for all recreational education after the completion of their entry-level scuba program for 12 months, either with the same instructor or same dive centre.

This means a student completing the PADI Advanced Open Water Diver course may enter the PADI Rescue Diver course with a different PADI Instructor at the same PADI dive centre, or change location and take the course with the same instructor.

It is now required for the PADI Advanced Open Water Diver course and the smart money would be to use it for every recreational continuing education program because of its flexibility. 

Its date depends on which side of the Equator you are on the Autumnal Equinox and its opposite, The Vernal or Spring Equinox signal the change in season just as the Summer and Winter Solstices do. 

Is this the start or end of your diving season?