Divesoft HE/02, Manual

Page: 11 / 31

10
The following formula is used for the calculation:
MOD =
P
max
ρ
g
R
O2
–P
O
where P
max
is the maximum allowable partial oxygen pressure, chosen as 160,000 Pa
P
0
is the static pressure at sea level, 101,325 Pa
R
O2
relative molar concentration of oxygen in the interval 0 to 1
ρ
is the seawater density, 1028 kg m
−3
g is the standard acceleration of gravity, 9.80665 m s
−2
Warning: The maximum operating depth (MOD) calculated for an actual dive is usually lower
than the depth indicated by the analyzer.
END is the depth at which the narcotic effect of the mix on the diver is identical to that of air.
It is specified in the percentage of a dive depth with air, i.e. for instance the END of 45 % means
that at a depth of 100 m with an analyzed mix, the diver will perceive the same narcotic effects
as if diving to 45 m with air. There are a number of various formulas for the calculation of END,
each giving different results. The value displayed by the analyzer uses only one of them and is
used for orientation purposes only. For an actual dive, it is necessary to calculate the END using
the data of the specific dive and the tested formulas of your preference.
The following formula is used for calculation:
END = 100 − 77 R
He
where R
He
is the relative molar concentration of helium in the ration 0 to 1
The formula is based on the following conditions:
— relative narcotic potential of nitrogen = 1
— relative narcotic potential of oxygen = 1
— relative narcotic potential of helium = 0.23
Warning: The equivalent narcotic depth (END) indicated by the calculation is for orientation
purposes only and may differ from the END values calculated using other methodologies.
Warning: To determine the END and MOD values, always use the procedures and formulas that
you learned in specialized courses of diving with mixes. The values indicated by the analyzer
are for orientation purposes only and are not sufficient for correct dive planning.