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Arterial gas embolism; lung over expansion injury caused by holding
your breath while ascending allowing air bubbles into the bloodstream
that block its flow. (Any foreign object in the bloodstream capable
of blocking flow is an embolism.)
A blue and white flag recognized as an International
Maritime flag. It indicates a vessel with limited movement, as
with diver or divers below.
Cessation of breathing
American Sign Language - one of the languages used by deaf
people and sometimes by divers for communicating with hand signals
Atmospheres Absolute Over Sea Level (ie gauge pressure)
Advanced open water certification; second level of certification
for some agencies
A tank with an emergency supply of breathing gas suitable for
one's depth (remember that oxygen is toxic at depth). It
bails one out of trouble with air supply, hence the name.
Short for barometric pressure? the method of measurement of air
pressure used throughout most of the world and by the compressed
gas industry. (see psi)
Buoyancy Compensator or Buoyancy Compensating/Control Device.
Inflatable device worn when scuba diving to assist with adjusting
At a constant temperature, the volume of a given mass of gas is
inversely proportional to the absolute pressure; if the pressure
goes up the volume goes down and vice versa
Slowing of the heart, triggered by cold moisture on the face while
Bottom Time a measurement or calculation of the amount of
time spent on a dive
Your diving partner while diving
Two divers sharing air from one second stage regulator or one
breathing from a safe second stage
A part of a tank valve that prevents the pressure in a scuba
tank from exceeding maximum operating pressure by bursting and
venting the tank.
Tight hood or wet suit causing pressure on the carotid arteries
can give a false high pressure signal and slow the heart unnecessarily:
carotid-sinus receptors send impulses to the cardio inhibitory
center of the brain
Closed Circuit Breathing Apparatus, a rebreather, a device
that reuses air by scrubbing or removing the carbon dioxide from
it. There are usually no bubbles emitted.
A term used to describe a crowded dive boat, where the divers
are like a herd of cattle.
Scuba diving certification card
Temperature has a direct relationship on pressure and or volume;
heat will make the pressure increase, heat will also make a flexible
object increase in size
One of many euphemisms for vomiting from seasickness as well as
attracting sharks with a mixture of blood and fish parts
Central Nervous System
Transmission of heat via direct contact. Divers are most affected
by conduction --- water conducts heat 25 times faster away from
a person's body than air
Transmission of heat via fluids. Water is warmed by a person and
rises, replaced by cooler water.
The total pressure of a gas mixture is equal to the sum of the
pressures of each of the different gases making up the mixture
Divers Alert Network; non-profit member organization that does
diving research and promotes diving safety
Decompression sickness, caissons' disease, or the bends; pressure
related injury caused by absorbing excess nitrogen under pressure
while diving; if coming up to fast or staying down too long the
nitrogen will form bubbles after or during ascent that will cause
pain or ill feeling or other symptoms; a common symptom is pain
in the joints causing atypical bending, hence the term "the bends";
symptoms may not appear until days later
The release of nitrogen from the tissues into the bloodstream
and out through the lungs
flag, Diver down flag
The dive flag used predominantly in the United States. It
is not recognized internationally yet is the one most used by
American divers. It is required to be used by them in many states
and locales when they are diving, and many locales have laws prohibiting
boaters and others from approaching within a specified distance.
Deutsches Institut fuer Normung - German Institute for Standardization
an organization that has set many standards, including in electronics.
When used in diving, it usually refers to DIN valves on tanks
which are a more secure design
A set of numbers that indicate the maximum time one may remain
at a particular depth without going into stage decompression diving,
thereby remaining within the no-decompression limits (NDL)
Diver Propulsion Vehicle, an underwater scooter used to pull divers
through the water (which conserves their air).
A dive made at a location (such as Cozumel, Mexico) where the
current can carry a diver along without finning being necessary.
Enriched Air Nitrox; air mixture with oxygen content above
21 per cent
Feet of fresh water
Feet of salt water
Generally refers to the part of the regulator that attaches to
the tank valve (see second stage) can also be part of stage
Mesh bag with locking wire frame used to carry goodies (see bugs)
The amount of gas that will dissolve into a liquid at a given
temperature is almost directly proportional to the partial pressure
of that gas
High Pressure Nervous Syndrome - a nervous disorder caused by
breathing air under high pressure, as in underwater habitats
A surface compressor supplying air via hoses to one or more divers
Excess carbon dioxide caused by diver failing to breathe slowly
and deeply or by heavy exertion. Headache may occur and may result
in loss of consciousness.
Insufficient carbon dioxide caused by voluntary or unintentional
hyperventilation. Carbon dioxide is what stimulates the breathing
action --- if not stimulated by carbon dioxide build up to breath
a diver or skin diver could use up more oxygen than he should
and could cause shallow water blackout when ascending.
Not enough oxygen in the bloodstream
Not receiving enough oxygen
When immersed a person will cool down causing constriction
of the blood vessels, the blood flow will be sent to the main
organs, away from the legs and the body will sense an increase
in fluids and send a signal to get rid of some fluid, causing
one to urinate
A valve with a spring loaded mechanism that allows a reserve of
air in the tank that can be actuated by pulling a lever secured
to the valve.
The standard valve in use today. Both J and K valves took their
names from the 1954 U.S. Divers catalog where they were items
J and K. Both J and K valves are yoke valves, which refers to
their attachment method.
Bag used to lift heavy objects underwater by filling the inverted
bag with air and using its buoyancy to lift the object
A diving boat that one stays on (lives aboard) as opposed to staying
in a hotel
A record of one's dives, including details of the dive. required
by some operators as proof of experience
Aair expansion injury; air accumulates in the chest pressing on
the heart and major blood vessels, interfering with circulation
and the person may feel short of breath
Meters of fresh water
Meters of salt water
Nitrogen narcosis; under the influence of nitrogen while diving
No Decompression Limit - the maximum time one may stay at
a particular depth in order to avoid decompression diving.
Naval Experimental Diving Unit (U.S.)
National Environment Research Council (UK)
A narcotic or intoxicating effect caused by nitrogen at depth
as pressure increases
Any gas mixture of nitrogen and oxygen; though most commonly
used for oxygen mixtures above the normal 21 per cent
National Oceanic and Atmospheric Administration (U.S.)
Naval Medical Research Institute (U.S.)
Extra second stage regulator used by your buddy in an out of air
Occupational Safety and Health Administration (U.S.)
Open water certification; first certification level
Air expansion injury; collapsed lung caused by air in the pleural
cavity; symptom would be coughing up blood
An auxiliary cylinder with an additional supply of air, an
alternate air source with its own regulator
Pounds per square inch; pressure measurement (see bar)
A valve on a snorkel, mask or regulator that allows it to be cleared
Recreational Dive Planner - a dive table for sport divers
developed by PADI
Remotely Operated Vehicle, often carrying cameras
Self-Contained Breathing Apparatus, such as what firefighters
Self-Contained Underwater Breathing Apparatus
Self Contained Underwater Drinking Apparatus. Product attached
to the second stage that can be used to drink underwater.
The part of the regulator that one breathes from (see first stage)
Surface Interval - the time between dives that allows for
Surface Interval Time - same as above.
A term used to refer to a small (American) dive boat, where Coast
Guard regulations only allow a maximum of six passengers
Scuba Lifesaving Accident Management course by the YMCA
Submersible Pressure Gauge - a gauge attached by a hose to
a first stage and indicating remaining air pressure in a tank.
Stab jacket, stabilizer jacket
A jacket style buoyancy compensator.
A reserve supply of breathing gas not carried with the diver.
an example is a stage bottle at the safety decompression stop
at 10-15 feet (approximately 3 to 5 meters) for divers who are
low on air at that point.
Air expansion injury; air in the soft tissues at the base of the
neck, person could feel a fullness in the neck and experience
a voice change.
See dive tables
Thermoclines are layers of water of different temperatures felt
when a transition to water of a different temperature (usually
colder when descending) is made.
United States Navy
Massive coral heads that extend from the depths are referred to
as walls, hence diving near them constitutes a wall dive
A humorous term referring to urinating in a wet suit and the resulting