Multi level dive
A single or repetitive dive that includes time spent at various depths and whose
no decompression limits are therefore not determined solely by the maximum
depth attained.
Nitrox
In sports diving, refers to any mix with a higher fraction of oxygen than standard
air.
NOAA
United States National Oceanic and Atmospheric Administration.
No decompression time
The maximum amount of time a diver may remain at a particular depth without
having to make decompression stops during the subsequent ascent.
No decompression dive
Any dive which permits a direct, uninterrupted ascent to the surface at any
time.
NO DEC TIME
Abbreviation for no decompression time limit.
OEA = EAN = EANx
Abbreviations for oxygen enriched air nitrox.
OLF
Abbreviation for oxygen limit fraction.
OTU
Abbreviation for oxygen tolerance unit.
Oxygen tolerance unit
Used to measure the whole-body-toxicity.
Oxygen limit fraction
A term used by Suunto for the values displayed in the oxygen toxicity bar graph.
The value is either the CNS% or the OTU%.
O
2
%
Oxygen percentage or oxygen fraction in the breathing gas. Standard air has
21% oxygen.
Oxygen partial pressure
Limits the maximum depth to which the nitrox mixture can be safely used. The
maximum partial pressure limit for enriched air diving is 1.4 bar. The contingency
partial pressure limit is 1.6 bar. Dives beyond this limit risk immediate oxygen
toxicity.
PO
2
Abbreviation for oxygen partial pressure.
RGBM
Abbreviation for Reduced Gradient Bubble Model.
Reduced Gradient Bubble Model
Modern algorithm for tracking both dissolved and free gas in divers.
Repetitive dive
Any dive whose decompression time limits are affected by residual nitrogen
absorbed during previous dives.
Residual nitrogen
The amount of excess nitrogen remaining in a diver after one or more dives.
SURF TIME
Abbreviation for surface interval time.
Surface interval time
Elapsed time between surfacing from a dive and beginning a descent for the
subsequent repetitive dive.
Tissue group
Theoretical concept used to model bodily tissues for the construction of
decompression tables or calculations.
Whole-body toxicity
Another form of oxygen toxicity, which is caused by prolonged exposure to
high oxygen partial pressures. The most common symptoms are irritation in
the lungs, a burning sensation in the chest, coughing and reduction of the vital
capacity. Also called Pulmonary Oxygen Toxicity. See also OTU.
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