lars2923

02-21-2007, 02:12 PM

Here are some common formulas. For those tec's out there, this is old stuff.

I post for the reference as well as for those who are curious. For the more

seasoned diver who if itchy to learn more about the physics of diving, this

will help out too. Look up the achronym online, ie END or MOD, SAC, TGC

(on how to calculate TGC), etc... to get a better idea of what and why. Of

course, get training as a Advanced Nitrox and/or Trimix diver to learn more.

As one becomes more techical, computers are good, but planning is important.

Computer programs available for purchase will help, but when you're out in the

field and there is not computer, knowing the formulas will come in handy.

This is not a comprehensive list of formulas, just some I choose to write

down. Why these particular formulas? Because they are the ones that came

to mind when writing this post.

EAD: Equivalent Air Depth

D: Depth

T: Time

TGC: Total Gas Consumed

FO: Fraction of Oxygen

TOD: Target Operating Depth

MOD: Maximum Operating Depth

END: Equivalent Nitrogen Depth

tEND: Target END

SAC: Surface Air Consumption

RMV: Respiratory Minute Volume

RCWP: Rated Cylinder Working Pressure

RCV: Rated Cylinder Volume

EAD: Equivalent Air Depth

FN: Fraction of Nitrogen

PO2: -or- PPO: Partial Pressure of Oxygen

FN = (EAD + 33) * .79 / (D + 33)

FO = PO2 / (( D / 33 ) + 1)

ie. FO = 1.4 / (( 132 / 33 ) + 1

TOD = (( PO2 / FO2 ) - 1 ) * 33

ie. TOD = (( 1.4 / .32 ) - 1 ) * 33

MOD = (( PO2 / FO2 ) - 1 ) * 33

ie. MOD = (( 1.6 / .32 ) - 1 ) * 33

END = ((tEND + 33) * .79) / ( D + 33)

SAC = TGC / ( D * T )

RMV = (( SAC / RCWP / RCV ))

EAD = ((( FN * ( D + 33 )) / .79 ) - 33

I'll post more later....

I post for the reference as well as for those who are curious. For the more

seasoned diver who if itchy to learn more about the physics of diving, this

will help out too. Look up the achronym online, ie END or MOD, SAC, TGC

(on how to calculate TGC), etc... to get a better idea of what and why. Of

course, get training as a Advanced Nitrox and/or Trimix diver to learn more.

As one becomes more techical, computers are good, but planning is important.

Computer programs available for purchase will help, but when you're out in the

field and there is not computer, knowing the formulas will come in handy.

This is not a comprehensive list of formulas, just some I choose to write

down. Why these particular formulas? Because they are the ones that came

to mind when writing this post.

EAD: Equivalent Air Depth

D: Depth

T: Time

TGC: Total Gas Consumed

FO: Fraction of Oxygen

TOD: Target Operating Depth

MOD: Maximum Operating Depth

END: Equivalent Nitrogen Depth

tEND: Target END

SAC: Surface Air Consumption

RMV: Respiratory Minute Volume

RCWP: Rated Cylinder Working Pressure

RCV: Rated Cylinder Volume

EAD: Equivalent Air Depth

FN: Fraction of Nitrogen

PO2: -or- PPO: Partial Pressure of Oxygen

FN = (EAD + 33) * .79 / (D + 33)

FO = PO2 / (( D / 33 ) + 1)

ie. FO = 1.4 / (( 132 / 33 ) + 1

TOD = (( PO2 / FO2 ) - 1 ) * 33

ie. TOD = (( 1.4 / .32 ) - 1 ) * 33

MOD = (( PO2 / FO2 ) - 1 ) * 33

ie. MOD = (( 1.6 / .32 ) - 1 ) * 33

END = ((tEND + 33) * .79) / ( D + 33)

SAC = TGC / ( D * T )

RMV = (( SAC / RCWP / RCV ))

EAD = ((( FN * ( D + 33 )) / .79 ) - 33

I'll post more later....