Rebreather sensors,
I am familiar with a few CCR units and can tell you how they "read" and where they are located..
The inspiration has 3 sensors located in the main gas flow with constant respiration the gas composition is fairly uniform, as a test I fitted a extra sensor right at the mouth piece and the readings from the controller and alternate sensor were always within .1 bar usually .05 bar or less, and any differances the RB sensors were usually slightly higher since the sensors are near the o2 injection point. If you monitor the controller as it injects o2 you see a rise of a few hundreds of a bar before it drops to is steady state point.
The mk15/ 15+/16 ect has its sensor within the gas flow but its a secondary path (not all the gas flows past the sensors)
The Cislunar has the sensors off the main gas flow.
All the sensor that I have checked have a rated response time of around 6 second for full scale(incedently this is the minimum time between o2 injections that the inspiration allows), for small fluctuations its basically real time..
Most RBs give you the actual sensor readings for all its cells, to maintain control most units use either a strict voting logic or combination voting/averaging logic to try and keep readings stable.
I initiate a dive with a setpoint of .7 and on decent o2 is never injected just diluent (manually) when doing a free decent to about 30m or so the PO2 is generally around .9-1.0, I am sure some people can attain readings higher than this but from experience the only times I have ever seen large spike is at the initial decent when not enough diluent was being added..
Automatic o2 additional is either done in the exhale lung (preferred) or after the scrubber and before the inhale bag, this gives some mixing time for the gasses.
I am familiar with a few CCR units and can tell you how they "read" and where they are located..
The inspiration has 3 sensors located in the main gas flow with constant respiration the gas composition is fairly uniform, as a test I fitted a extra sensor right at the mouth piece and the readings from the controller and alternate sensor were always within .1 bar usually .05 bar or less, and any differances the RB sensors were usually slightly higher since the sensors are near the o2 injection point. If you monitor the controller as it injects o2 you see a rise of a few hundreds of a bar before it drops to is steady state point.
The mk15/ 15+/16 ect has its sensor within the gas flow but its a secondary path (not all the gas flows past the sensors)
The Cislunar has the sensors off the main gas flow.
All the sensor that I have checked have a rated response time of around 6 second for full scale(incedently this is the minimum time between o2 injections that the inspiration allows), for small fluctuations its basically real time..
Most RBs give you the actual sensor readings for all its cells, to maintain control most units use either a strict voting logic or combination voting/averaging logic to try and keep readings stable.
I initiate a dive with a setpoint of .7 and on decent o2 is never injected just diluent (manually) when doing a free decent to about 30m or so the PO2 is generally around .9-1.0, I am sure some people can attain readings higher than this but from experience the only times I have ever seen large spike is at the initial decent when not enough diluent was being added..
Automatic o2 additional is either done in the exhale lung (preferred) or after the scrubber and before the inhale bag, this gives some mixing time for the gasses.