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GLOSSARY
Altitude dive
A dive madeat an elevation greaterthan 300 m/1000ft above sea level.
Ascent rate
The speed atwhich the diver ascendstoward the surface.
ASC RATE
Abbreviation for ascentrate.
Ascent time
Theminimumamountoftimeneededtoreachthesurfaceonadecompression
stop dive.
ASC TIME
Abbreviation for ascenttime.
Ceiling
On adecompression stopdive, the shallowestdepth towhich adiver may as-
cend based oncomputed nitrogen load.
Central nervous systemtoxicity
Toxicity caused by oxygen. Can cause a variety of neurological symptoms.
The mostimportant ofwhich isan epileptic-like convulsionwhich cancause a
diver to drown.
CNS
Abbreviation for centralnervous system toxicity.
CNS%
Central nervoussystem toxicitylimit fraction. Alsonote OxygenLimit Fraction
Compartment
See "Tissue group".
DAN
Abbreviation for DiversAlert Network.
DCI
Abbreviation for decompressionillness.
Decompression
Time spent at a decompression stop, or range, beforesurfacing, to allow ab-
sorbed nitrogen toescape naturally from tissues
Decompression range
On a decompression stop dive, the depth range between the floor and the
ceiling within whicha diver must stopfor some timeduring ascent.
Decompression illness
Any of a variety of maladies resulting either directly or indirectly from the
formation of nitrogen bubbles in tissues or body fluids, as a result of inad-
equately controlled decompression.Commonly called "thebends" or "DCI".
Dive series
A group of repetitive dives between which the dive computer indicates some
nitrogen loading is present. When nitrogen loading reaches zero the dive
computer deactivates.
Dive time
Elapsed time between leaving the surface to descend, and returning to the
surface at theend of a dive.
EAD
Abbreviation for equivalentair depth.
EAN
Abbreviation for enrichedair nitrox.
Enriched air nitrox
Also called nitrox or Enriched Air = EANx. Air that has some oxygen added.
Standard mixesare EAN32 (NOAANitrox I= NN I)and EAN36(NOAA Nitrox
II = NNII).
Equivalent air depth
Nitrogen partial pressureequivalent table.
Floor
Thedeepestdepth duringadecompression stopdiveat whichdecompression
takes place.
Half time
Aftera changein ambientpressure,the amountof timerequired forthe partial
pressureof nitrogenin atheoreticalcompartment togo halfwayfrom itsprevi-
ous value tosaturation at thenew ambient pressure.
He%
Helium percentage orhelium fraction in thebreathing gas.
Heliox
A breathing gasmix of helium andoxygen.
Multi level dive
Asingleorrepetitivedivethatincludestimespentatvariousdepthsandwhose
no decompressionlimits are thereforenot determined solelyby the maximum
depth attained.
Nitrox
Insportsdiving,refers toanymix withahigherfraction ofoxygenthanstandard
air.
NOAA
United States NationalOceanic and AtmosphericAdministration.
No decompression time
Themaximum amountof timeadiver mayremain ataparticular depthwithout
having to makedecompression stops during thesubsequent ascent.
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