Primarily for general aviation discussion, but other aviation topics are also welcome.
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By MikeB
FLYER Club Member  FLYER Club Member
#1844984
riverrock wrote:For ref:
35ppm The maximum allowable concentration for continuous exposure for healthy adults in any 8 hour period, as recommended by the
Occupational Safety and Health Administration (OSHA).
200ppm Slight headache, fatigue, dizziness, nausea after 2 - 3 hours.
400ppm Frontal headaches within 1 - 2 hours, life threatening after 3 hours.
800ppm Dizziness, nausea and convulsions within 45 minutes. Unconsciousness within 2
hours. Death within 2 - 3 hours.


Regarding the above table, presume that is for breathing at typical sea level pressures (may even use ISA). As the oxygen partial pressure reduces with altitude, I suggest the above safe limits will reduce. Frank?
#1854713
Interested in this subject, we have just fitted a sensitive detector in our Jodel (following an engine rebuild). Is it the case, that you want to see 0 on the detector during flight, or what is the expected experience of other users of devices where you can see the actual ppm displayed?

In our initial test flights post-rebuild, we are seeing from 15-25 regularly and depending on how we set the vents, max 75 ppm once. We don't know what we had prior to the rebuild as didn't have the detector then......

We are looking at the engine bay and underside panels as the culprits, the Jodel tends to 'suck' air into the cabin and potentially we have an unsealed panel somewhere below - the two exhausts run externally along the bottom of the fuselage and vent directly below the seats (through a perforated tube).

I have seen that exposure (over time) of >35ppm is not healthy. I would rather not be exposed to any, but is it realistic to expect say 0, 15ppm or whatever during normal flight operations. Just wondering how far we need to go to investigate and remedy.

Interestingly, we know its not the heater pipes - integrated with the frontal exhaust section - when we were testing readings during flight, the opening of cabin vent and heater vent *improved /lowered* the detected ppm, suggesting it alleviated the 'suck' of the cabin from outside.

We are going to check the firewall and underside panels for seals.

Anybody else with a Jodel and CO detector?
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By Dave W
FLYER Club Member  FLYER Club Member
#1854733
I have a Jodel 1051 with an O-235 fitted. We have a CO detector fitted at shoulderblade height just behind the front seat pax on the fuselage wall shelf.

We see 0 ppm all the time, so I think you have an issue.
#1854745
Dave W wrote:I have a Jodel 1051 with an O-235 fitted. We have a CO detector fitted at shoulderblade height just behind the front seat pax on the fuselage wall shelf.

We see 0 ppm all the time, so I think you have an issue.


Some of the domestic detectors show 0 until a threshold and only the actual level above that - guess to stop people worrying about normal levels in a house. The manual should tell you if that's the case.

Edit: Just checked the manual for our FireAngel CO-9D, it shows zero for levels of 10ppm or lower and only displays the actual level if 11ppm or higher. Don't know if other detectors have different thresholds?

Cheers,
Tim
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By TopCat
FLYER Club Member  FLYER Club Member
#1854752
I've got one of these.

It has a continuous ppm readout, and an alarm sounds if the level is high enough for long enough. 60-90 mins apparently at 50ppm.

I get about 50ppm in a full-power full-rich climb; it drops very quickly to zero in the cruise. I'm not overly concerned at that level, but I'm keeping an eye on it.

I have it on the floor in the P2 footwell where I can see it - I take a glance at it when I check the carb heat, which is every ten minutes or so.
By riverrock
FLYER Club Member  FLYER Club Member
#1854766
We have a DR1050 - we always get a positive reading until in the cruise. We've spent a lot of effort blocking gaps and holes and it has improved to acceptable levels, but not zero. It's the buildup at low levels which could be the issue, but the FireAngel has a nice guage showing buildup which never moves above minimum.
#1854823
Interesting, my take from the WHO study mentioned:

Normal background CO levels in the environment <1ppm

Urban traffic environments in European cities concentrations over 8 hours <17ppm, short peak <53ppm

CO levels higher in personal cars, 2-5x street measurements depending on traffic patterns /urban /car model.

Underground /multi-storey car parks >100ppm over several hours

Homes with gas appliances peak concentrations 53-100ppm

Smoking and altitude increase the CO effects of hypoxia (oxygen starvation).
#1854828
Shoestring Flyer wrote:Can it be turned off though? A loud noise distraction from a minor increase is the problem.
I have mentioned my concerns on this issue with these things before.
If not what do you do with it when it starts bleating away? ...Especially in a tip up canopy cockpit!


Yes. There’s an on/off button on the front. It takes about a minute or so to self-calibrate when you turn it on. :thumright:
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