Half time
After a change in ambient pressure, the amount of time required for the
partial pressure of nitrogen in a theoretical compartment to go half way
from its previous value to saturation at the new ambient pressure.
He%
Helium percentage or helium fraction in the breathing gas.
HP
Abbreviation for high pressure (= cylinder pressure).
MOD
The maximum operating depth of a breathing gas is the depth at which
the partial pressure of oxygen (PO2) of the gas mix exceeds a safe limit.
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 as-
cent.
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.
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