A clogged alternate second-stage regulator leads to a free-flow for one diver. Here's what happened and our best tips for dealing with it.

Incident Report

Divers: Jon (OW, 12 dives) and Kate (OW, 14 dives) Site: Beach dive, Southern California, 48-foot maximum depth Conditions: Visibility 20 feet, 68˚F, low surf

Jon and Kate waded through waist-high surf, descended and swam over a sandy bottom along a reef and into deeper water. About 200 yards out, at 40 feet, they found kelp growing on the reef. They swam a short distance under the light canopy, looking up at the sunlight playing through the kelp. Kate grabbed her alternate second stage, which was dangling unsecured, and pressed the purge to send a bubble burst through the kelp.

It began to free-flow violently. Turning its mouthpiece down didn’t help; Jon took it and slapped it, but the flow continued. Wide-eyed and in a cloud of bubbles, Kate bolted up through the kelp, still breathing from her primary, with Jon following at a safe rate. After they reunited on the surface, Jon had to inflate her BC and close her cylinder valve to stop the flow.

They surface-swam to shore and exited without incident. Luckily, despite the fast ascent, neither experienced DCI symptoms. Later, a local dive center’s service technician found the second stage clogged with sand, which had jammed it open when Kate pushed the purge.

What They Did Wrong

Kate failed to secure her alternate and she swam too close to the bottom, causing the regulator to fill with sand. Kate ascended at an unsafe rate and ascended through kelp, which could have caused entanglement had it been thicker.

What They Did Right

Jon ascended at an appropriate rate. He ensured that Kate was buoyant before closing her cylinder valve. They didn’t attempt to descend again with malfunctioning gear.

Five Tips From This Incident

1 Don't let your alternate air source (or anything else) dangle. It’s harder to locate in an out-of-air emergency and might be useless if it’s full of sand or mud.

2 If your alternate has been dragging (perhaps accidentally unclipped), don’t purge, but swish it back and forth to clear as much sand as possible. A little sand clears with purging, but a substantial amount can jam things open, causing a free-flow.

3 You can breathe from a free-flowing regulator (a skill you will have learned in the PADI Open Water Diver course). Don’t panic; often the other second stage works normally.

4 If a runaway free-flow occurs, ascend immediately at a safe rate. Avoid ascending through kelp. Stay with your buddy to share air in case the free-flow exhausts your supply.

5 Don't dive again with gear that has experienced a problem until it’s been checked and repaired by a qualified technician.