Mathematical Formulas
Used in Nitrox Diving Calculations
Metric/S.I. Calculations
Boyle’s Law
P1V1 = P2V2
Dalton’s Law
Or, as formulas:
Pg = Fg x Ptotal
Fg = Pg /Ptotal
Ptotal = Pg /Fg
Converting Depth to Absolute Pressure
Pbar Dmsw absolute 1
Or
= +
Pbar = Dmsw +10
msw absolute
Converting Absolute Pressure to Depth
Or
Calculating Maximum Operating Depth
In two steps:
P bar = PO2 limit / FO2
followed by:
Or, in one step:
PO
⎛
= −
2limit × ⎟ ⎟⎠
Dmsw 1 10 /
Calculating Best Mix
In two steps:
Pbar = Dmsw +
1
followed by:
FO2 = PO2 limit / P bar
Or, in one step:
PO msw bar
⎛
FO PO Dmsw
⎞
= ⎟ ⎟⎠
⎜ ⎜⎝
= ÷ +
Calculating Equivalent Air Depth
In two steps:
Pbar = Dmsw +
absolute 1
followed by:
Or, in one step:
bar
msw bar
10 /
msw bar
10 /
Dmsw (Pbar bar) msw bar = absolute −1 ×10 /
Dmsw (Pbar msw atm) msw = absolute ×10 / −10
Dmsw (Pbar bar) msw bar = absolute −1 ×10 /
bar msw bar
FO
2
⎞
⎜ ⎜⎝
bar
msw bar
10 /
10 /
×
Dmsw msw
msw bar
10
1
10 /
2limit
2 2limit +
bar
msw bar
10 /
Dmsw (Pbar bar) msw bar = absolute −1 ×10 /
( ) EADmsw Dmsw msw FN 10msw
⎜ ⎞
⎝
10 2 ⎟ −
0.79
⎠
= ⎛ + ×
Partial
Pressure
Total
Pressure
Gas
Fraction
Formulas
NAUI Nitrox Diver
96