Air Supply Problem

A friend of mine was concerned that her pressure gauge, which was reading 1,000 psi underwater, would drop to zero psi as she took a breath and then popped back up to 1,000.

This happens when you don't have your tank valve fully opened (usually 3-4 turns) and you start running low on air. You basically are sucking all the air out of the hoses faster than the partially-opened valve can replenish the supply. That is why the pressure drops to zero psi, even if it's just momentary.

But she swears the tank valve was opened fully, so the other option was that something was wrong inside the regulator's first stage. She was advised to stop using it immediately and have it checked. Running out of breathing gas is a major problem, so you should always check your tank valve before jumping in the water to ensure it's fully open.

Besides physically opening the valve, one quick way to check is to take a huge breath on the regulator while you watch the gauge. Even a digital gauge shouldn't budge. If you see the pressure dropping, even just a little bit, and then rising, either the valve is not open entirely, or something inside your regulator is blocking the airflow. Correct the issue before you submerge.

And one more thing. It's important to go over your out-of-air options before you submerge. If you're diving with a buddy, discuss octopus breathing, buddy breathing, which regulator will be donated, and other options before you go under.

Ken Kurtis

http://www.reefseekers.com