Left-sided tank valve causes an out-of-air incident

Reported Story

A diver who was traveling outside of the U.S. was rented an air tank with the valve on the left rather than the right. Maximum depth of dive was 95 fsw (29 msw). 40 minutes into the dive at 30 fsw (9 msw), the diver developed difficulty breathing and noticed his pressure gauge fluctuating between 1,600 psi and 500 psi. The diver assumed his tank valve was not open completely so he tried to reach the valve and open it but was not successful. As he swam over to the divemaster, he ran out of air. He signaled that he was out of air and was given his divemaster's primary while the divemaster took his own alternate air. The diver signaled to have the divemaster open his tank valve. Once he did, the diver's air returned and his pressure gauge read over 1,000 psi. The diver returned the divemaster's primary air and replaced with his own. The dive continued without incident.


In Open Water class, divers are taught to always open tank valves completely then turn the valve one quarter turn back. This lets the diver know his/her tank is indeed on and prevents the valve from becoming stuck on the open position. Most standard scuba tanks have valves on the right so divers turn them all the way away from the body and ¼ turn back This can be confusing when the tank valve is on the opposite side. If a diver turns a left-sided valve away from the body and ¼ turn back as they are taught in class, they are actually closing the tank instead of opening it. In this particular case, the tank valve was only open one quarter turn. As the air emptied from the tank, it became increasingly difficult for the diver to draw air. Eventually, the diver's pressure gauge began fluctuating between 1,600 psi and 500 psi. This is a very common occurrence when a tank valve is not open completely. Fortunately, the diver recognized his problem and signaled the divemaster who opened his valve and the dive continued with no further problems. Had this diver not recognized the problem, he may have panicked and had an uncontrolled ascent to the surface increasing his risk of both decompression sickness and AGE. This diver's risk for DCI was significant as his deepest depth was 95 fsw (29 msw) and total dive time up to the out-of-air incident was 40 minutes so nitrogen load was sufficient to cause symptoms.

If ever presented with a piece of equipment that you are not familiar with, always ask for assistance. Never assume anything. Using unfamiliar equipment can be dangerous if you are not educated on its use. Educate yourself ahead of time. Call the dive shop/operator prior to your trip and ask about equipment that you will be using. If something is not familiar, ask questions. Garner as much information as possible ahead of time. Internet travel review sites and scuba blogs are a good place to start. Talk to others that have been diving at that location before. This provides insight on what to expect. Because this diver was not familiar with this type of tank, he did not realize the tank valve was only partially open and it caused an out-of-air incident that could have been catastrophic.

~ Lana P. Sorrell, EMT, DMT