Air consumption rate not calculated

Discussion of the iOS App Dive Log
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Joined: Mon Dec 04, 2017 9:39 pm

Air consumption rate not calculated

Post by Dieseltwitch » Mon Dec 04, 2017 9:42 pm

I new to diving and trying to keep track of the rate of air consumption. However, the app is not calculating the actual rate of air consumption. How do I fix this?

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Joined: Wed Mar 31, 2010 4:35 pm

Re: Air consumption rate not calculated

Post by support » Wed Dec 06, 2017 11:19 am

In order to calculate Air Consumption rate the following values are requires:

- average depth
- dive time
- tank size (including working pressure if you are specifying tank sizes in "US/Canadian" units of Cu Ft)
- air consumed (starting tank pressure - ending tank pressure)

Depending on your dive computer, most of these values are downloaded when you download your dive computer. However, if you are not using a dive computer or you are using a dive computer that does not include tank size information (most don't actually) then you need to enter those values. Similarly, if you dive computer is not "air integrated" you will need to add the stat and end tank pressure as well.

If you have a profile for your dive downloaded from a dive computer then the average depth and dive time will be calculated from that profile. If you are manually entering dives you will need to add these values. Both of them are available to enter/edit from the Dive Details screen by tapping on the "profile sketch" on iPhone and then tapping Edit or by tapping Edit on iPad and then tapping on the individual items.

The tank information is set by tapping on the "tank" row on the Dive Details screen. Then make sure that you have entered the tank size (if you are using imperial units then make sure you also enter the tank's working pressure) and the start and end pressures.

You should now see the Air Consumption rate displayed next to the tank information. Note that there are multiple ways to calculate Air Consumption rate (search for SAC and RMC if you are interested in the details). Dive Log is calculating air consumption rate normalized to the ambient pressure during the dive (i.e. the average depth). This is the method that allow you to compare one dive to the next due to the fact that the rate is normalize for depth (recall that each breath at 10 meters/33 feet uses twice as much volume of air as a breath at the surface due to gas compression). This is also the rate most commonly used to predict your how long your air will last on a planned dive since it accounts for the dive depth.

I hope that helps. Please let me know if you need any additional information.



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