RESEARCH, EDUCATION & MEDICINE
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E X P E R T O P I N I O N S
50
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WINTER 2014
B Y P E T A R D E N O B L E , M . D . , D . S C .
Tank Valves and
Out-Of-Air Emergencies
O
ut-of-air situations are the most com-
mon cause of fatal diving accidents.
Surprisingly, these problems some-
times occur at the very beginning
of dives when the diver should still
have a full tank of compressed gas. How is this pos-
sible? Recently such case was reported through DAN’s
Diving Incident Report System (DIRS). The following
is a brief summary of the case.
A few minutes into the dive, while still descending,
the diver dropped his weights and surfaced in a hurry.
His dive guide surfaced next and found him at the
surface panicking and out of his BCD. The diver’s BCD
was empty of gas and could not be inflated. His tank
appeared to have no pressure. The guide inflated the
victim’s BCD orally, and the victim calmed down. The
guide then checked the valve of the victim’s tank and
found it closed. He opened the valve and found the
pressure in the tank to be 2,200 psi. The victim said that
a few minutes into the dive, as he descended to 30 feet, he
suddenly had no air. He never explained why he got out
of his BCD or whether or not he closed the tank.
The diver most likely did not sufficiently open the tank
valve before his descent. The valve was open enough to
provide some air at the surface and in shallow water. As
the diver descended, however, he did not get enough
air. He tried to open the tank, but in the attempt he
turned the valve in the wrong direction, shutting it
Incompletely open tank valves can lead to out-of-air situations,
the most common causes of fatal dive accidents.
STEPHEN FRINK
