PO2 alert in oc mode

[dadefay]

Hi,

For a few days I dive with air in open circuit using release 3.26, and I encountered several PO2 alerts close to the surface. The threshold was initially set to 0.21 (several alerts), then to 0.20 (several alerts again) and finally to 0.15 (one alert). The surface pressure reported by my OSTC is about 1005 hPa.

In the SubSurface file, one can find theses lines :
<event time='0:02 min' type='20' name='pO₂' />
<event time='16:58 min' type='20' name='pO₂' />
<event time='18:12 min' type='20' name='pO₂' />
<event time='19:14 min' type='20' name='pO₂' />
<event time='20:16 min' type='20' name='pO₂' />
<event time='21:18 min' type='20' name='pO₂' />
<event time='22:20 min' type='20' name='pO₂' />
<event time='23:22 min' type='20' name='pO₂' />
<event time='24:24 min' type='20' name='pO₂' />
<event time='25:26 min' type='20' name='pO₂' />
<event time='26:28 min' type='20' name='pO₂' />

I never saw that behaviour in open circuit with release 3.24 or with 3.26 in closed circuit.

Kind regards.

[heinrichsweikamp]

Hi,

Do you see these errors on the dive computer screen, too?

There really is no known issue with the ppo2 warnings in the 3.26 and we do not see such errors during our weekly diving at all.

regards,
Matthias

[dadefay]

Hi,

Yes, I saw theses alerts on the OSTC screen. During the last dives with the threshold set to 0.16 bar, no such warning occurred. I set it to 0.21 bar again for the next dives, to see if the problem comes again.

Kind regards.

[heinrichsweikamp]

Hi,

With 0.21bar as the threshold you'll see ppO2 low warnings on the surface since the alarm is shown when 0.209 is reached and the pressure reading is <1000hpa. Bear in mind that the displayed surface pressure is artificially stabilized and only an average value is displayed. This prevents the display from always jumping back and forth a few hPa (which means we have to answer emails straight away). For those familiar with the code, pressure_abs_10 is used for the warnings, pressure_surf is shown in the surface mode screen.

Regards,
Matthias

[dadefay]

Hi Matthias,

This error was reported several times once at the surface today. The surface pressure reported by the OSTC (found in the subsurface file is 1016 hPa :

<surface pressure='1.016 bar' />

This gives a PO2 = 0.213 bar...

Regards.