June 17th, 2009

NiTek X Desat Calculation

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We received two NiTek X units in service due to display errors. The DESAT information would not come back once the X was awakened after going into sleep mode. I tested it and found this to be true, but random. I then learned the following from the programmers.

DESAT, or desaturation time is the amount of time that must pass before the residual nitrogen and helium levels drop to a point where subsequent dives are treated as a single (non-repetitive) dive. This is not the same as “time to fly”.  On the NiTek X DESAT times are displayed when the PGT bar graph (on the right of the computer screen) is showing one or more bars.

This explanation gives more merit to tracking tissue saturation than a 12 to 48 hour countdown most dive computers do including the earlier NiTek 3 and NiTek HE.  When diving the NiTek X I see a noticeable reduction in decompression time compared to the NiTek Plus. A 60 minute dive at 100-feet using 32% Nitrox gives me 15 minutes of decompression on the NiTek Plus and then 8 minutes after switching to oxygen at 10-feet. The NiTek X only gives me 1 minute of decompression on Con 1 setting.  The more information a dive computer uses to calculate decompression the better the results. The X uses 16 tissue compartments while the NiTek Plus uses only 9 compartments. You can customize the X for deep diving with variable gradient factors to make the decompression fit the environment.

We’ll look at adding a standard countdown in the next software upgrade.

Lamar

2 Responses to “NiTek X Desat Calculation”

  • Hi,
    my Nitek X never gives me a “normal” DESAT Time after a Dive.
    The DESAT Time starts for example with 20:30 hours then goes to 23:45 hours, then to 22:35 hours ans so on. If you watch it you can see that it will come slowly to 0 hours after a normal DESAT Time (look on another Divecomputer). But why does the time jump? The Nitek X was only on a table for look at it – no flying, driving with the car overs mountains or any other situation where the air pressure changes.
    Any suggestions?
    I am from Germany and i like the computer but i don’t trust it at the moment.
    Greetings
    Michael

    Michael Keimes, March 30th, 2010 at 2:44 am

  • Michael,

    It’s all in the accuracy. The unit samples and displays the desat time as it measures ambient pressure to a fraction. These changes happen more often than people realize. We could have given it a range before changing or let it do desat in real time. We chose real time and so the reason for it fluctuating as it does.

    Lamar

    lamar, April 2nd, 2010 at 2:23 pm