





Units

PSIG

PSIA

ATM

ATA

FSW

FSWA

FFW

FFWA

PSIG


Add 14.7

Divide by 14.7

Add 14.7, Divide by 14.7

Divide by 0.445

Divide by 0.445 Add 33

Divide by 0.432

Divide by 0.432, Add 33

PSIA

Subtract 14.7


Subtract 14.7, Divide by 14.7

Divide by 14.7

Subtract 14.7, Divide by 0.445

Divide by 0.445

Subtract 14.7, Divide by 0.432

Divide by 0.432

ATM

Multiply by 14.7

Multiply by 14.7, Add 14.7


Add 1

Multiply by 33

Multiply by 33, Add 33

Multiply by 34

Multiply by 34, Add 34

ATA

Subtract 1, Multiply by 14.7

Multiply by 14.7

Subtract 1


Multiply by 33, Subtract 33

Multiply by 33

Multiply by 34, Subtract 34

Multiply by 34

FSW

Multiply by 0.445

Multiply by 0.445, add 14.7

Divide by 33

Add 33, Divide by 33


Add 33

Multiply by 1.03

Multiply by 1.03, Add 34

FSWA

Subtract 33, multiply by 0.445

Multiply by 0.445

Subtract 33, Divide by 33

Divide by 33

Subtract 33


Subtract 33, Multiply by 1.03

Multiply by 1.03

FFW

Multiply by 0.432

Multiply by 0.432, add 14.7

Divide by 34

Add 34, Divide by 34

Multiply by 0.97

Add 34, Multiply by 0.97


Add 34

FFWA

Subtract 34, Multiply by 0.432

Multiply by 0.432

Subtract 34, Divide by 34

Divide by 34

Subtract 34, Multiply by 0.97

Multiply by 0.97

Subtract 34






PSIG = Pounds per Square Inch (Gauge) PSIA = Pounds per Square Inch (Absolute) ATM = Atmospheres ATA = Atmospheres (Absolute)
FSW = Feet of Sea Water FSWA = Feet of Sea Water (Absolute) FFW = Feet of Fresh Water FFWA = Feet of Fresh Water (Absolute)
“T” formula
Partial Pressure

Total Pressure

% Gas


Partial Pressure = Total Pressure X % Gas
% Gas = Partial Pressure / Total Pressure
Total Pressure = Partial Pressure / % Gas
Calculating PO2: PO2 = Depth in atmospheres absolute (ATA) X percentage O2
Calculating MOD: MOD = ((Maximum PO2 (normally 1.6 or 1.4) / % Fraction of Gas (%O2)) 1 atmosphere) X 33
Calculating EAD: Salt Water ((1 FO2/.79) X (D+33))  33
Calculating Surface Consumption Rate (SCR) in PSI/MIN:
Converting SCR from PSI/MIN to Cubic Feet/MIN:
Calculating Air Consumption at depth:
Calculating how long a tank will last at depth:
Temperature Conversions:
Degrees Celcius = .556 X (Degrees Farenhiet  32)
Degrees Farenhiet = (1.8 X Degrees Celcius) + 32
Degrees Kelvin = Degrees Celcius + 273

