Hi,
Could you explain this setting in a little more detail?
In my AP Inspiration, when I am calibrating O2 cells, the OXIGEN % is requested. It is requesting the oxygen % in the scrubber lid after the oxigen inject take place during calibration. Default value is 98%.
It is not clear to me that the setting in the OSTC refers to the same setting I use during calibration. Mainly because the default value in the OSTC is 90%, far away from the default 98% on my AP.
BR
Maximum O2 content in the loop
Maximum O2 content in the loop
mobu
OSTC plus #16088
OSTC plus #16088
Re: Maximum O2 content in the loop
Hi,
the default value is actually 21%, but you can set any value between 21% and 100%.
The set value will be stored, so once you change it to 98% it stays at 98%.
BR
Ralph
the default value is actually 21%, but you can set any value between 21% and 100%.
The set value will be stored, so once you change it to 98% it stays at 98%.
BR
Ralph
Re: Maximum O2 content in the loop
Hi Ralph,
In the OSTC manual you can read that it can be set between 80% and 100%. In fact, in my OSTC I can only set a value between 80% and 100%. I cannot set a value lower than 80%.
Anyway, I would like to know what this set refers to. Could you explain a bit more?
Also whether it should have the same value as the one entered in the AP when I calibrate the O2 cells.
BR
Mobu
In the OSTC manual you can read that it can be set between 80% and 100%. In fact, in my OSTC I can only set a value between 80% and 100%. I cannot set a value lower than 80%.
Anyway, I would like to know what this set refers to. Could you explain a bit more?
Also whether it should have the same value as the one entered in the AP when I calibrate the O2 cells.
BR
Mobu
mobu
OSTC plus #16088
OSTC plus #16088
Re: Maximum O2 content in the loop
Ah, sorry, i confused with the calibration menue.
Here's a 1:1 copy of the code where this setting gets into use:
// get the current sensor reading (CCR / pSCR if fitted) or the fixed setpoint (CCR) / a zero (pSCR)
const_ppO2 = 0.01 * char_I_const_ppO2;
// Limit the setpoint to the maximum physically possible ppO2. This prevents for
// example calculating with a setpoint of 1.3 bar in only 2 meters of depth.
// Additionally, the ppO2 can be further reduced to account for exhaled inert gases
// accumulating in the loop by the user-adjustable setting char_I_CC_max_frac_O2.
// (ppWater is neglected here)
max_ppO2 = 0.01 * char_I_CC_max_frac_O2 * calc_pres_respiration;
if( const_ppO2 > max_ppO2 ) const_ppO2 = max_ppO2;
So actually it is a safeguard for the ppO2 (origining either from the currently selected SP or from the external sensors) that goes into the deco calculation, by limiting it to the maximum physically possible ppO2 according to:
1) the current depth aka ambient pressure,
2) some percentage factor below the current depth aka ambient pressure to "account for exhaled inert gases accumulating in the loop".
--> Any setting < 100% works to the safe side by lowering the ppO2 that goes into the deco calculation, hence rising the ppN2 & ppHe, hence generating a bit more deco when the selected SP or measured ppO2 becomes unfeasable. As long as you are deeper than ~3.3 meters (3m/90%) on a SP of 1.3 bar, or your sensors measure a ppO2 lower than <set percentage> x ambient pressure (what they should do by nature), the SP value or the measured ppO2 value will be used straight as it is.
Here's a 1:1 copy of the code where this setting gets into use:
// get the current sensor reading (CCR / pSCR if fitted) or the fixed setpoint (CCR) / a zero (pSCR)
const_ppO2 = 0.01 * char_I_const_ppO2;
// Limit the setpoint to the maximum physically possible ppO2. This prevents for
// example calculating with a setpoint of 1.3 bar in only 2 meters of depth.
// Additionally, the ppO2 can be further reduced to account for exhaled inert gases
// accumulating in the loop by the user-adjustable setting char_I_CC_max_frac_O2.
// (ppWater is neglected here)
max_ppO2 = 0.01 * char_I_CC_max_frac_O2 * calc_pres_respiration;
if( const_ppO2 > max_ppO2 ) const_ppO2 = max_ppO2;
So actually it is a safeguard for the ppO2 (origining either from the currently selected SP or from the external sensors) that goes into the deco calculation, by limiting it to the maximum physically possible ppO2 according to:
1) the current depth aka ambient pressure,
2) some percentage factor below the current depth aka ambient pressure to "account for exhaled inert gases accumulating in the loop".
--> Any setting < 100% works to the safe side by lowering the ppO2 that goes into the deco calculation, hence rising the ppN2 & ppHe, hence generating a bit more deco when the selected SP or measured ppO2 becomes unfeasable. As long as you are deeper than ~3.3 meters (3m/90%) on a SP of 1.3 bar, or your sensors measure a ppO2 lower than <set percentage> x ambient pressure (what they should do by nature), the SP value or the measured ppO2 value will be used straight as it is.