Although standards and safe diving practices dictate that we always carry an alternate air source, they do not dictate which kind.

Be open-minded about equipment configurations when diving and teaching. Just because someone's equipment doesn't fall into the preconceived categories such as 'standard' or 'normal' it doesn't mean it isn't safe and functional.

H-Valves, CCRs, Sidemount and even the Octopus Alternate Air Source wouldn't be part of everyday diving if it wasn't for those looking to innovate equipment and technique. 

Learn more about equipment in diving and its history and innovation, during your PADI Divemaster and PADI Instructor Development Course. Book Now.

If you're reading this, you must be on the internet. Do yourself a favour and search for Dalton's Triangle - a priceless tool in determining either the Maximum Operating Depth, Fraction of Oxygen or Partial Pressure of gases in a mix, based on the other two factors in the equation. 

Let's do the math on this one first though - Ean40 means the fraction of Oxygen in the blend is 40% O2. If the ppO2 (Partial Pressure of Oxygen) is 1.4 max. we need to divide the ppO2 by the FO2 to find the atmospheric pressure the blend can be used at - 1.4 / 0.40 = 3.6 ATA

Now we convert ATA - Atmospheres Absolute - into the depth of seawater - 3.6 - 1 = 2.6, 2.6 X 10 = 26m/sw

Learn more about physics in diving and its practical application in your PADI Divemaster course and the PADI IDC. Book Now and Ignite Your Life today!

Tidal Volume is approximately 500ml per breath or 7ml/1Kg of bodyweight - with a relaxed diver it makes it easier to guesstimate breathing rates during training and non-training dives and helps you plan dives better. 

Learn more about diving physiology in your PADI Divemaster course and PADI Instructor Development Course. 

Maximum Depth is the third mode found on the eRDPml - input the data found from a previous dive and surface interval along with the time available to complete the repetitive dive and it will give you the maximum depth allowed for that dive.

A handy planning tool to have when trying to make the most out of your diving day while remaining conservative within the no-stop limits.

Learn more about dive planning on your PADI Divemaster and PADI IDC. Book Now and Ignite Your Life today!

Membership Status is covered in the last section of the PADI Instructor Manual - in it, you'll find what Active, Review and Teaching status means.

If a member is currently in Review Status they may not apply for either Master Instructor or Course Director but may still teach and certify PADI courses.