CCR Divers: Hold Your Nose

Pre-breathe – Hold your nose!

Do you ever see your colleagues walking around the boat deck or dive site while pre-breathing on their rig? This is a dangerous practice. Pre-breathing should be conducted in a safe place while watching  your displays.

Did you know that it is important to either pinch your nose or wear a mask while you complete your pre-breathe sequence? If you fail to pinch your nose, and you have a carbon dioxide issue like channeling, a bad mushroom valve or absent canister, then your body will compensate for the rising PCO2 by sneaking in some fresh air through the nose. You may not even notice, but it negates the main safety purpose for the pre-breathe sequence. So, find a safe and relaxed spot to complete your pre-breathe. Watch and compare your displays and then after you pass the test, you can enter the water safely.

Comments

[Marc Laukien]

Thanks for the tip! I never realized how much I unconsciously inhaled and exhaled through the nose during pre-breathing. The difference is measurable. I always wondered why my ppO2 during pre-breathing was dropping so fast. Today, I pinched my nose during pre-breathing, and it dropped at the expected rate, meaning that without noticing, I was breathing partially through the nose before.