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 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.
2) The valve can possibly stick open.
Can you damage a valve by opening it too hard? “Yes” it is 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 are 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”.
Can valves stick open? “Yes” but not for the reason that people propagate this antiquated procedure. The industry
has improved over the years and the brass style valves that could “stick open” have NOT been manufactured in over 50
years. The no longer exist in the scuba industry. The valves designed today for the scuba industry, 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.
What if a valve gets stuck open? Firstly, this means the owner of that tank has not been properly maintaining their
equipment and there is corrosion within the valve mechanisms. As the 1st stage regulator is under pressure and impossible
to remove you simply need to empty the tank by depressing the 2nd stage to release all the pressure from the tank. Once
empty the 1st stage then can be removed and the tank must be serviced properly.
Why is a quarter turn or half turn an issue?
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.
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.”
Most of the major training organizations which include PADI, TDI/SDI, BSAC, GUE and DAN all say “turn it all the way on”.
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.
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