Jolly Roger Diving

Puerto Lindo, Panama

/blog/quarterturn

Old Habits never die, but divers do!

Within many industries there are methods that people have been taught to do things that honestly are no longer relevant. Within diving it’s the Quarter Turn on tank valves. Otherwise known as “THE QUARTER TURN OF DEATH!”

For many years people have propagated many reasons why it’s important to open a tank fully and then turn it back one quarter turn. Two of the most typical reasons are; 1) You can damage the valve by opening it too hard. or 2) The valve can possibly stick open. With the first “yes” it is technically possible to damage a valve by forcing it to open further than it already is. This goes the same for closing a valve too hard. Inside a valve is soft plastic and rubber components that seal a valve closed or open. Too much pressure on these surfaces will over time cause them to wear out sooner than expected. “So, what!” these soft parts literally cost pennies and can be replaced in less than 15 minutes. I personally would rather replace these parts more often knowing that divers are safe versus “saving a few pennies”. For the second item people need to realize that the industry has improved over the years and the brass style valves that could “stick open” have NOT been manufactured in over 50 years. Today’s scuba valves, when properly maintained, DO NOT stick open or stick closed! It is actually impossible for this to happen as the design of the valve won’t allow this to happen. For those valves that have not been properly maintained the valve will be hard to turn as this is a sign that there is corrosion within the valve mechanisms. This is a potential sign that the owner of the tank is NOT properly maintaining their equipment.

When a valve is only opened a quarter turn or a half turn you may not notice any difference in the function of the regulator at the surface but once you descend the pressure changes will cause the regulator to breath harder and eventually it will fail to function as the partially opened valve won’t be able to supply enough air for the regulator to function properly.

Most of the major training organizations which include PADI, TDI/SDI, BSAC, GUE and DAN all say “turn it all the way on”.

At Jolly Roger Diving our policy is: “All the way ON, or all the way off! A quarter turn is a quarter turn away from death.”

There have been numerous occurrences of individuals running out of air due to a tank that is not fully open and in some of these instances it has led to the diver’s death. Each year DAN (Divers Alert Network) publishes an Annual Diving Report. In the 2018 report there is a documented case of a diver that ran out of air due to a valve being turned closed then opened only a quarter of a turn.

Case 3-410:
A valve not fully open, or fully closed
I went on a guided dive trip for my first dive after receiving my open water certification two months previously. I rented a complete set of gear for the dive. We got on the boat, and I put on the wetsuit and started to put together the BCD and regulators.

I was having a hard time listening to the captain talk while I was trying to remember everything I was supposed to do. The captain saw I was slow to put everything together, so when we arrived at the dive site, he came over and put the gear together for me. He checked the alternate regulator for airflow, and I pushed both buttons on the BCD, and the air flow was fine. He told me to wait and be the last person off the boat so he could recheck everything before I got in the water.

As I lined up at the bow, I took a breath and exhaled from the regulator. It felt strange so I said to the captain, “It feels tight, is that OK?” He said it was fine. I got in the water and joined the group. A fellow diver saw that one of the shoulder straps on my BCD was twisted, so she unclipped it, untwisted it, then checked the other clips on my BCD. I thanked her for the help. Then we all descended. My descent was easy and without incident, but when I got to the bottom, I couldn’t get a good breath. I didn’t understand what I was doing wrong, and just focused on staying relaxed and breathing slowly and evenly. It was difficult to breathe. The air seemed to be “stuttering” in my regulator. I took the regulator out of my mouth, then put it back in and cleared it, and continued to focus and to try to regulate my breathing. I was concentrating on moving slowly and evenly and breathing regularly. But none of it was working. I was still struggling to breathe and bouncing (mostly sinking).

All this time, I had been following fins to stay with the group but then realized I was alone. I did a 360o turn and didn’t see any fins, so I decided to ascend. I quickly reviewed in my mind what to do and started to ascend, still having trouble breathing.

When I surfaced, I gave the distress signal to the boat. The captain swam out and towed me to the boat. On the boat, the captain told me the air valve was completely shut off. I didn’t understand fully what he was saying at first. He didn’t know how that could have happened and called it an equipment malfunction.

After resting, I continued the dive as a snorkeler. The captain had been the last person to touch my valve before I got in the water, and no one touched it while I was in the water. The captain said he turned it fully on and a quarter turn back. Since I know the valve was open before I put on the BCD, the only explanation for the closed valve, and the breathing difficulties I had underwater, is that the captain must have shut off the valve and turned it a quarter turn back on by mistake.

DAN Comment: The days when divers would turn valves all the way on and back a quarter turn are long behind us. Today there is no need for the quarter turn; it is safer to open dive tank valves all the way.

There was also an incident in Florida in 2003 in which a diver perished with more than 140 bar/ 2000 psi of air remaining in his tank. All because his tank valve was only open one quarter of a turn. Published in the Daytona Beach News-Journal

A few more incidents that involved tanks that were only partially opened:
DAN: Left-sided tank valve causes an out-of-air incident.
Single Divers Forum: Tanks on - half turn back or not?

Other dive publications that also do not support the partial turn methodology:
Cave Diver Harry: The Quarter Turn That Kills.
Divers Alert Network: Alert Diver Online - Tank Valves and Out-Of-Air Emergencies
Scuba Diver Life: Valve On, Valve Off