100 NAUI Nitrox Diver
Appendix D
MATHEMATICAL FORMULAS
USED IN NITROX DIVING
CALCULATIONS
METRIC/S.I. CALCULATIONS
Boyle’s Law
P1V1 = P2V2
Dalton’s Law
÷ ÷
Or, as formulas:
Pg =Fg × Ptotal
Fg =Pg / Ptotal
Ptotal =Pg / Fg
Converting Depth to Absolute Pressure
or
Converting Absolute Pressure to Depth
or
Calculating Maximum Operating Depth
In two steps:
followed by:
Or, in one step:
Calculating Best Mix
In two steps:
followed by:
Or, in one step:
Calculating Equivalent Air Depth
In two steps:
followed by:
Or, in one step:
Pbarabsolute = D m s w + 1 bar
10 msw / bar
Pbarabsolute = D m s w + 1 0 m s w
10 msw / bar
D msw = (Pbarabsolute - 1 bar) × 10 msw / bar
D msw = (Pbarabsolute × 10 msw / bar) - 10 msw
P bar = PO2 limit / FO2
D msw = (Pbarabsolute − 1 bar) × 10 msw / bar
D msw = ( P O 2 l i m i t - 1 b ar) × 10 msw / bar
FO2
Pbar = D m s w + 1 bar
10 msw / bar
FO2 = PO2 limit / P bar
FO2 = PO2 limit ÷( m 10 msw D s /w bar
) +1 =
PO2 limit × 10 msw/bar
D msw + 10 msw
Pbarabsolute = D m s w + 1 bar
10 msw / bar
D msw = (Pbarabsolute - 1 bar) × 10 msw/bar
(D msw + 10 msw) × EAD msw = ( FN2
) - 10 msw 0.79
Partial
Pressure
Total
Pressure
Gas
X Fraction