Question about gas consumption in simulator

[ian1000]

I have just started using my ostc 2n and im very impressed overall with the computer, however i have a question regarding gas consumption calculation in the dive planner/simulator, i can enter two gases, air bottom gas and 80% nitrox for deco and plan a dive to 54m for 15mins and the gas consumption will show as being 1003 litres of nx80 for ten mins of deco at 6m and 2mins at 9m? This result is completely wrong?
Equally i can plan a dive to 60m for 15mins bottom time using air and nx80 and get nx 80 deco of 3mins at 9m and 13min at 6m and gas usage of 561 litres which is completely correct? Why is the nx80 gas usage for planning a dive to 54m for 15 min wrong? No settings are changed, in the custom functions the gas consumption is set to 20L/min for bioth bottom and deco mixes.

Btw the computer is new and running version 2.5 software, am i missing something really obvious here or is the computer just wrong?

[DTR.Diver66]

Hello Ian,

BUGFIX Gas volumes when many tanks and stops. You have to wait for the next beta or stable.


Regards

[Clownfish]

Just ran the simulations on my computer which is also 2.50. Without knowing exactly what settings you are using (eg GF), I got almost similar last two stops as you did on the 54 m dive but only 395 litres. On the 60 m dive I again got almost identical stops and 529 litres. I suggest you need to check what you did.

[Bardass]

There's a bug when CF54=0 and gaz not swap at the MOD

[ian1000]

Hi thanks for the replies, regards settings, i am running conservatism factor instead of gradient factors its set up in standard form of 90 and 110%, all the settings in cf are standard apart from changing last stop depth to 6m instead of 3m. The gas comsumption is spot on for loads of different dives i enter but for sone reason it just gives dodgy nx 80 consumption for 15mins at 54m? If its a bug that known then fare enough i just wasn't expecting it to give me a wrong quantity for something but i understand its open source and work in progress etc. its a great piece of kit.

[Bardass]

what is the value for CF54 ?

[ian1000]

Hi, its set deepest stop at stop, which is its default value, as i say all thats not default on the custom settings is the last stop depth which is set to 6m, thanks,

Ian

[ian1000]

Sorry deepest stop at top i ment, nx 80 value is at the bottom of the deco stops list

[Bardass]

Oups
I mean CF55, sorry
GasVolume is badly approximated when CF55=0

https://bitbucket.org/heinrichsweikamp/ ... dd2cc026e5

[ian1000]

Yes cf 55 is indeed set to zero, strange though that 54m for 15mins is affected whereas 60m for 15min is correct, its not like gas volume used is always badly approximated its just that one depth when planning, its just coincedence that the very first deco dive ive went to plan on my new computer hsppened to be 54m, if it had of been 35m or something different id never have known it can be wrong. I think the gas volume used being shown in the dive planning is a really nice feature of the computer so i hope it gets the bugs sorted out for this some time in the future.

[Bardass]

I described this problem to Jeando a month ago
since it is corrected in beta and will be fixed in future stable version

with CF55=0
Modèle Bühlmann ZH-L16C-1a 2002 standard:
* facteur de saturation (CF11) = 120 %
* facteur de désaturation (CF12) = 90 %
* marge de palier (CF16) = 1.0 m
* dernier palier (CF29) = 6 m
* début de plongée à Pamb = 991 mbar
* Durée de changement de gaz (CF55) = 0 min

Liste des gaz OC:
* Premier gaz#1 = 21/0
* Gaz déco#2 = 80/0 à 10 m

0:00 54.0m DESCENT DONE
...
15:00 54.0m Déco:
9 m : 3 ' 22 ' (CHANGER Gaz#1 -> Gaz#2)
6 m : 11 ' 34 '
0 m : --- ' 35 '
DTR = 21 '
SNC = 20%

DTR Réchap @+3' = 29'
RT Réchap @+3' = 47'
==== OC Runtime ====
15:06 54.0m Déco:
9 m : 3 ' 22 ' (CHANGER Gaz#1 -> Gaz#2)
6 m : 11 ' 34 '
0 m : --- ' 35 '
DTR = 21 '
SNC = 20%
Profondeur = 54 m
Temps fond = 15 min
Conso gaz fond (CF56) = 22 l/min
Conso gaz déco (CF57) = 17 l/min
Gaz#1 ( 21/00) = 2112
Gaz#2 ( 80/00) = 912

with CF55=1
Modèle Bühlmann ZH-L16C-1a 2002 standard:
* facteur de saturation (CF11) = 120 %
* facteur de désaturation (CF12) = 90 %
* marge de palier (CF16) = 1.0 m
* dernier palier (CF29) = 6 m
* début de plongée à Pamb = 991 mbar
* Durée de changement de gaz (CF55) = 1 min

Liste des gaz OC:
* Premier gaz#1 = 21/0
* Gaz déco#2 = 80/0 à 10 m

0:00 54.0m DESCENT DONE
...
15:00 54.0m Déco:
10 m : 1 ' 20 ' (CHANGER Gaz#1 -> Gaz#2)
9 m : 2 ' 22 '
6 m : 11 ' 34 '
0 m : --- ' 35 '
DTR = 21 '
SNC = 21%

DTR Réchap @+3' = 29'
RT Réchap @+3' = 47'
==== OC Runtime ====
15:06 54.0m Déco:
10 m : 1 ' 20 ' (CHANGER Gaz#1 -> Gaz#2)
9 m : 2 ' 22 '
6 m : 12 ' 35 '
0 m : --- ' 36 '
DTR = 22 '
SNC = 22%
Profondeur = 54 m
Temps fond = 15 min
Conso gaz fond (CF56) = 22 l/min
Conso gaz déco (CF57) = 17 l/min
Gaz#1 ( 21/00) = 2591
Gaz#2 ( 80/00) = 454

[ian1000]

Yeah thats it, so change cf55 to 1 and its corrected, i'll do that, good to know its already been spotted and is being looked into, thanks for the help. As i said the computers excellent, really pleased with it, looking forward to giving it a try this weekend.

[heinrichsweikamp]

Hi,

This is fixed already and will be included in the new beta, which we'll post today or tomorrow.

Regards,
Matthias