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5

COMEX procedure

simple procedure:

without any compartments or half-times

without supersaturations

only one free parameter (λ)

„Best Fit“ to many successful C&R and SAT dives,

and a lot of deep diving experiments,

for e.g.: Hydra series, up to 700 m,

data base: pls. cf. next slide

Legend:

SAT : saturation dives, dive time > 72 h

C&R : construction & repair diving

Sources: [1], [2] & COMEX homepage

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The COMEX procedure

The COMEX procedure:

D0

D(t) = ------------------------------------

1 + λ * T-5/2 * D0-3 * (t – T)

with the following parameters:

D(t) : (actual) diving depth [m] as a function of diving time t, t > T

T : bottom time [min]

D0 : bottom depth [m]

λ : empirical parameter [min2m3], used to fit for:

breathing mix, Helium- and Oxygen fraction

water- / ambient temperature

workload

decompression chamber- or working dive (with immersion)

Sources: [1], [2]; pls. cf. slide #20

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The COMEX procedure

Due to the technical nature of SAT dives &

the deep diving experiments, there is headspace

in the decompression procedures. There are

different values for the parameters for:

workload of divers

Helium fraction

pO2 @ bottom, @ decompression

ambient temperature, …

risk appetite of the company

…

In the COMEX procedure this is reflected via the parameter λ.

As an example pls. cf. the next slides: decompression from

a SAT dive in the AQUARIUS habitat (Florida, 18 m):

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Decompression from the AQUARIUS habitat

USN SAT procedure: 1140 min: 4 h + 15 h = 19 h (Air only)

Bühlmann SAT 20: 660 min: 11 h (with 6 h @ 100% O2)

Aquarius procedure: 990 min: 16,5 h (with 1 h @ 100 % O2 @ 60 feet)

COMEX procedure: 1190 min: 19,8 h (Air only) with λ = 999.990.000.000

DIVE V 3_09: 1860 min (upper limit of ascent rate)

2700 min (lower limit of ascent rate, AIR only)

DIVE V 3_09: 1600 min (upper limit of ascent rate, from 10 m @ 100 % O2)

12

Decompression from the AQUARIUS habitat

USN SAT procedure: 1140 min: 4 h + 15 h = 19 h (Air only)

Bühlmann SAT 20: 660 min: 11 h (with 6 h @ 100% O2)

Aquarius procedure: 990 min: 16,5 h (with 1 h @ 100 % O2 @ 60 feet)

COMEX procedure: 1190 min: 19,8 h (Air only) with λ = 999.990.000.000

DIVE V 3_09: 1860 min (upper limit of ascent rate)

2700 min (lower limit of ascent rate, AIR only)

DIVE V 3_09: 1600 min (upper limit of ascent rate, from 10 m @ 100 % O2)

Legend:

•USN: SAT procedure per USN Diving Manual, Rev. 7 2018,

Chapter 13, Table 13 – 9:

•Bühlmann SAT 20: table from the DKL-USZ, pls. cf. next slide

•Aquarius: proprietary procedure in the habitat, which rests on the

sea bed, after decompression the divers ascend to the surface

•COMEX: procedure with λ= 9.999 exp 11

13

Decompression from the AQUARIUS habitat

USN SAT procedure: 1140 min: 4 h + 15 h = 19 h (Air only)

Bühlmann SAT 20: 660 min: 11 h (with 6 h @ 100% O2)

Aquarius procedure: 990 min: 16,5 h (with 1 h @ 100 % O2 @ 60 feet)

COMEX procedure: 1190 min: 19,8 h (Air only) with λ = 999.990.000.000

DIVE V 3_09: 1860 min (upper limit of ascent rate)

2700 min (lower limit of ascent rate, AIR only)

DIVE V 3_09: 1600 min (upper limit of ascent rate, from 10 m @ 100 % O2)

14

The COMEX procedure

The formula describes the diving depth D(t)

in relation to the diving time t, after bottom time T.

As there are no PTC/bells available for rec/TEC dives, a continuous

ascent is technically not feasible: decompression is done in stages,

usually 10 feet / 3 m apart. The stop times are listed with each stage.

Thus for a rec/TEC bounce dive, the times from the COMEX procedure

have to be integrated (summed up) around a median, i.e.: (N * 3) +/- Δ.

Example with Δ = 1.5 m for a 6 m stop (N = 2):

the integration in the time-domain for this 6 m stop is then done from

6 + 1.5 = 7.5 6 – 1.5 = 4.5 m

This rationale is feasible for deep rec/deep TEC dives, usually much

like a box profile due to limited supply of breathing gas & thermal

protection:

if it fits to SAT diving, it fits even more so to bounce dives, since the

more sensitive body tissues are not affected by short bounce dives.

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the test dive: D0 = 42 m, T = 25 min

Output from DIVE Version 3_09:

λ = 122.0 exp 6 matches a standard ZH-L16 C decompression schedule

top of slide # 16, with TTS = 28 min

λ = 100.5 exp 6 conservative, similar to VPM: TTS = 37 min

λ = 165.0 exp 6 aggressive, similar to RGBM: TTS = 22 min

details: pls. cf. the next 2 slides

Legend:

TTS: time-to-surface, i.e.:

(bottom depth/ascent rate) + sum of all stop times

VPM: Varying Permeability Model, Ref. [3]

RGBM: Reduced Gradient Bubble Model, Ref. [4]

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Sources / References:

[1] Bernard Gardette (November 2009) : THEORIE GENERALE

UNIFIEE DE LA DECOMPRESSION;

Directeur Scientifique COMEX, BG/sc-060/09

[2] Alexis Blasselle, Michael Theron, Bernard Gardette, Emmanuel

Dugrenot (2020) A new form of admissible pressure for Haldanian

decompression models

[3] Yount, D.E. Hoffman, D.C. (1986) On the use of a Bubble

Formation Model to calculate diving tables

[4] Wienke, B. R. (2003) RGBM in-depth

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Bonus Material:

Source for

DIVE Version 3_09

Download free of charge:

DIVE V 3_09

(https://www.divetable.info/DIVE_V3/index.htm)

and the german manual

https://www.divetable.info/DIVE_V3/DOXV3_0.pdf

The release train for

the english version (V3_04) is somewhat slower …

https://www.divetable.info/DIVE_V3/V3e/index.htm

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Fine tuning could be done via the commands:

ascent rate („AR“)

ambient atmospheric pressure at start („L“)

the respiratory coefficient („R“)

the ambient (water)-temperature („te“)

the water density („di“)

Buehlmann Safety Factor („B“)

last stop depth („LS“)

And with: „a“ we recieve the complete decompression prognosis;

i.e.: the stop times in min per stage, modulo 3 m

and the responsible leading compartment & the rounded up TTS in

min. The latest DIVE Version for beta testing is always staged there:

https://www.divetable.info/beta/index.htm

along with information on production date, size in bytes, new features and

the checksums for verifying the download.

Fine tuning of DIVE:

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The test dive from above via the commands,

the input of commands and parameters are in the quotes: „ “

(ZH-L 16 C is the default coeffcients matrix)

„d“ (simulation of a box profile with these parameters:)

„42.“ (bottom depth)

„25.“ (bottom time)

„a“ „“ (yields this standard decompression prognosis):

the COMEX procedure is simulated via: „cp“

pls. cf. slides #16, 18 & 19

the dialogue to manipulate the gradient factors is invoked with: „GF“

Handling of DIVE: