Igor P
New Member
Let me see if I can do something ..... but the video should run streaming good enought .....
CO2 Monitor (End-tidal) - good news
- Thread starter gianaameri
- Start date
Let me see if I can do something ..... but the video should run streaming good enought .....
gianaameri
gian @ gian.ameri.name
The relevant information/lesson from the dive test dive is that the sensor in open air should read approx. 0.04.
That was the first dive and I had left the sensor in the humid rebreather during transport and it started reading high (about 0.07).
Then in use it went even higher, 0.15.
Still acceptable, but if the sensor is instead placed in the rebreather immediately pre-dive, and removed post-dive, as I learned later is the right thing to do, I get consistent readings of 0.04 in open air, and 0.02 in the loop (inhale side).
At any rate, I am happy with the way it is for the inhale side, and now I am moving at building something for end-tidal CO2 transdermal inside the dry-suit, and it will also read O2 the same way.
Igor P
New Member
Have you tried simulating Hypercapnia (coutch simulation)? What were readings if yess?
That would be interesting to know, and how fast does CO2 build up. How much time do we have to react on first alarms ... etc
That would be interesting to know, and how fast does CO2 build up. How much time do we have to react on first alarms ... etc
gianaameri
gian @ gian.ameri.name
Tried with bump test gas and also exhaling on the sensor. You can see response time in the videos.
It reacts within maybe less than 10 secs. and settles to the correct reading in maybe about 30 secs., off the top of my head.
Using 1% CO2 bump test gas is more accurate and telling than breathing in the loop with no scrubber.
At the end of the dive I remove the sensor from the loop and it is as responsive as pre-dive.
gianaameri
gian @ gian.ameri.name
Nice to see that Golem is taking the CO2 Monitor homebuilder experiment one step further adding a very nice 1 ATA case.
This will be the most serious and tangible advancement in rebreather diving safety available to all and at an accessible price (next step will be transdermal end-tidal CO2 monitoring).
This will be the most serious and tangible advancement in rebreather diving safety available to all and at an accessible price (next step will be transdermal end-tidal CO2 monitoring).
Igor P
New Member
Nice to see that Golem is taking the CO2 Monitor homebuilder experiment one step further adding a very nice 1 ATA case.
This will be the most serious and tangible advancement in rebreather diving safety available to all and at an accessible price (next step will be transdermal end-tidal CO2 monitoring).
What will be the price?? Did you hear anything?
gianaameri
gian @ gian.ameri.name
No idea yet... but I hope they include an HUD.
I found out it is essential, especially when scootering in a cave.
It is just a "Go/NoGo" type instrument and all you need to know is a. that it is ON (no flood/no dead battery) and b. to be alerted when you CO2 is above the alarm threshold (in my case 0.5% CO2).
I got lost once in the cave scootering being distracted by the 1 ATA box for the CO2 monitor I was experimenting with... a line was making a 40 degrees turn to the left, following a long straight stretch, and it was awhite line on a white background, and fiddling with the 1 ATA box I temporarily covered the line section which was going left, all scootering of course, and ended up going straight and suddenly the line disappeared in front of me (so had to make a crash stop, 180 degree turn, and get back to the line before the silt cloud reached it).
Ben Field
All IMVHO obviously...
Really?
(I could argue about CO2 monitoring in general, my belief is its more emporers new clothes...)
But- I would say the most serious and tangible advancement in rebreather diving safety would be accurate and reliable PPO2 monitoring, it is by far the weakest facet of current CCR technology and the most important. Frankly everything else is just "shiney"
IMVHO it would be better to design CO2 breakthrough and WOB out of the units and skip straight to end-tidal monitoring only (monitor the diver not the unit)
lizardland
Active Member
Couldnt agree more. Galvanic cells to monitor O2 wasnt the greatest system when we had a decent manufacturer available and with the current suppliers is positively shite.
I couldnt care less about a CO2 monitor. Invent a reliable bombproof ppo2 monitoring system and that really would be worth celebrating.
Instead someone has built a monitor that rebreathers have managed fine without for 40 years.
I have to agree as well, better design from the start is probably a far more useful step. Reliable rebreathers with reliable ppo2 monitoring. The rest is gadgets.
Sent from my GT-I9100 using Tapatalk
Ben Field
All IMVHO obviously...
Possibly... but its another display that if giving a "good to go" reading when it isn't might have the effect of keeping you on a loop you feel dubious about.
Controversial- better to have "less" information and bailout when its unnecessary than die because the CO2-ometer says its okay.
We need- PPO2 and Deco
What we're offered by manufacturers- Breathing rate (too high, too low) automated pre-breath, Digital SPG's, rate of Dil/O2 usage alarms, tempstiks, CO2 alarms, stack timers, battery testers, dual controllers, games? etc....
What happened to gut feeling and diver knowledge? Surely this is another sticking plaster to cover woeful training and unit design?
(OK- I am delibrately being obtuse :thumbsup: but I think its a valid question)
gianaameri
gian @ gian.ameri.name
Surely, I think both my opinion and your are true and valid.
That is why I use reliable Homebuilt pPO2 monitor and a reliable Homebuilt CO2 monitor in addition and to fill the gap relative to what until now has been available out-of-the-box from rebreather/integrated dive computers manufacturers.
gianaameri
gian @ gian.ameri.name
Johan Isaksson
Member
Transdermal monitoring can easily combine pCO2 monitoring with pO2 monitoring, there are brands available were the probe measures both. I doubt it can handle hyperoxia due to how it works but it'd cover hypoxia at least.
matt
Well-Known Member
I know nothing of transdermal monitoring, how fast does it measure the actual gas ppO2/PCO2 and where does the probe go?
Matt.
gianaameri
gian @ gian.ameri.name
In a specific place, but hard to make it stick and stay in place, but we will get there.
There is a scientific research published explaining all of this (maybe Dr. Simon Mitchell can contribute).
matt
Well-Known Member
How many breaths does it take to get the reading? Sounds very different to gas analysis which is done before the breath.
Matt.
gianaameri
gian @ gian.ameri.name
The reading is of the CO2 in the blood. It takes no breaths as it is already there.
Presumably, if you do not breathe at all (you pause your breath), but the heart beats, I suspect the CO2 reading from the transdermal sensor actually goes up.
It is the CO2 content in the blood that is what we want to know to to measure retained CO2 or excessive levels of CO2.
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matt
Well-Known Member
gianaameri
gian @ gian.ameri.name
We got O2 Cells for pPO2.
I'd rather stick with the devil I know (i.e. O2 Cells), than the one I don't (transdermal measurement of O2).
However, once we get the trasndermal sensor working fine with a board and fully secure in position (stuck to the skin) at the right location for measuring arterial CO2, conceptually it could be used to verify pPO2 as well at the blood level... one step at the time though.
The priority for me is getting the transdermal sesnsor working for arterial CO2 measurments, and that is my next Homebuilder project priority.