Breathing from a Free-Flowing Scuba Diving Regulator

A second-stage free flow regulator happens when the downstream valve in the second stage sticks wide open. Most of us have experienced that at one time or other at the surface. You place your regulator in the water at the surface with its mouthpiece face-up, and the next thing you know, your reg is wildly free-flowing. Usually, all you have to do is put your thumb or hand over the mouthpiece or turn the reg face-down, submerged in the water. At the surface, a free-flowing regulator is annoying, but at depth, a regulator locked in free-flow can be dangerous.


Cold water is the No. 1 culprit behind a free-flowing regulator, but there are less-common reasons, too. For example, there have been instances of a diver using their octopus reg to inflate an SMB, only to have it free-flow. A second stage that is clogged with sand, jamming the valve open.

RegulatorsSuddenly, you’re immersed in more bubbles than those produced by a Jacuzzi. So what should you do if your regulator free flows at depth? You can continue to breathe from a free-flowing second stage as you surface, and during your open-water training, you practiced this skill. Follow our tips for dealing with it calmly and safely.

1) Remember your training. Invoke the mantra Stop, Think, Breathe, Act.

2) Remove the second stage from your mouth. Tilt the mouthpiece so that it’s partially in your mouth — grip it on the right side of your mouth as normal, but left the left side rest lightly on your lips, just outside of your mouth. (This allows excess air to escape through the sides of your mouth.)

3) Press the purge button and use your tongue as a splash guard against the roof of your mouth to prevent choking on water. Tilt your head to the right.

4) Keep your mouth slightly open and breathe carefully and calmly from the free-flowing air bubbling next to your mouth.

5) Ascend at a safe rate. A free-flow will deplete your air supply in a matter of minutes, so it’s important that you surface as soon as possible.

6) Once you surface, close the cylinder valve to stop the free-flow.

7) Practice this skill in the pool. It’s not a great feeling to have your reg free-flow, but in the unlikely case it happens to you, it’s best to have practiced this skill. A pool is a safe environment for you to get comfortable with the skill.

Of course, there are other options:

1) If you carry a pony tank, switch to your bail-out gas, and then safely ascend.

2) Switch to your buddy’s alternate air source, and then surface together.

You know the old saying — an ounce of prevention is worth a pound of cure? That’s certainly the case with a free-flowing reg:

1) Make sure your reg is serviced regularly. Don’t dive again with a reg that has experienced a problem until it’s been checked and repaired by a qualified technician.

2) When diving in cold water, get a cold-water regulator that’s designed to prevent free-flows.

3) Don’t let your reg or alternate air source drag on the bottom or beach as it might get clogged with sand or mud.

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