Equivalent Air Density Depth (EADD)

[Trace Malinowski]

Many of us probably find the Equivalent Air Density Depth (EADD) useful or at least interesting when running the gas planning feature in V-Planner. V-Planner not only provides EADs and ENDs, but the EADD as well. Does anyone know what the formula is to arrive at EADD? Both metric and imperial conversions would be fantastic! Thanks.

 

[PfcAJ]

Gas density @ 1ata in kg/m^3

O2 1.429
N2 1.250
He 0.179
CO2 1.977

Density of air at 0m (O2 + N2)
(1.429 x .21 x 1ata) + (1.250 x .79 x 1ata) = 1.288 kg/m^3

Density of trimix 12/35 at 50m (O2 + He + N2)
(1.429 x .21 x 6ata) + ( 0.179 x .35 x 6ata) + ( 1.250 x .44 x 6ata) =5.47644 kg/m^3

Which gives an EADD of 4.252ATA or 32.5m or 107.25ft.

Seems about right.

So I think that comes out to
(gas densityO2 x pp x ata)+(gas densityHe x pp x ata)+(gas densityN2 x pp x ata) = GasDensity@Depth

EADD = (GD@D/1.288)-1x10




---------- Post added January 8th, 2014 at 02:55 PM ----------

PS: I didn't come up with that myself. A guy with the username of Steve on rebreatherworld gave me the framework.

 

[Trace Malinowski]

Awesome.