How much carbon monoxide is too much?

[RobertE]

OK, I know that the easy answer is "anything more than zero", but I don't think that's realistic. In our kitchen I get a reading sometimes of 2 or 3 PPM.

Anyway, in cruise I show about 5 PPM but in the climb I see from 10-20 ( the longer the climb the higher the number). So I know something is going on.

Would you be concerned with the above fact pattern?

Thanks.

 

 

[Brandontwalker]

I saw mine peak at 36 ppm in climb and back down to 5-6 in cruise. That appears to be common, but concerning when the red lights start flashing.


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[201er]

So are we all getting dosed with carbon monoxide when we fly? Or is the meter overly sensitive? 

Are you guys getting those readings with cabin heat on or off?

[AlexLev]

Not sure how concerning a small amount is, I think 25ppm is actually allowed for an 8-hour work day: "max 8-hour avg CO level allowed in occupational settings for an 8-hour workday over a 40-hour workweek by the American Conference of Governmental Industrial Hygienists."

However, it would be something I'd be curious about and fix at the very least at annual if possible. My CO meter = 5-8ppm when on the ground and 3-5ppm in climb and 0ppm eventually during cruise within 5minutes or so even with cabin heat fully on. I do have it mounted by the door though, so I'm not sure if that makes a difference.

Edited March 13, 2017 by AlexLev

[carusoam]

I think we are collecting information in a couple of threads...

Somebody else reported seeing higher numbers during a slow climb.

Made him want to verify what was taped and sealed near the nose gear and rudder pedals...

Best regards,

-a-

[201er]

Has anyone tried holding one of these up to an exhaust pipe to see what a highball amount is? Does the unit degrade whenever it is making a reading or is it solely by age?

[carusoam]

Check the device docs for warnings...  blasting a sensitive sensor may have some ill side effects...

A car with a working catalytic converter may not show the highest numbers.  Cats don't work until they warm up.

I hope it would be strong enough to handle the blast...  some customers will want to try it out without reading...

Or forget what they read over time...

Best regards,

-a-

[jaylw314]

On the M20J, the bellcranks for the cowl flaps are RIGHT up against the SCAT tube from the exhaust shroud to the cabin.  This is the correct routing depicted in the maintenance manual, but there is almost no clearance.  My last annual, they replaced the SCAT tube because of some small holes, and when I did my oil change, the bellcranks had shredded the SCAT tube.  Once the SCAT tube gets a hole, it becomes less rigid and sags a little, which makes it rub against the bellcranks more.  My A&P redid it and zip-tied the SCAT tube to squash it and keep it away from the crank, but it is still really close.

Long story short--check the SCAT hose from the exhaust shroud and make sure there are no holes.

I bought the Sensorcon detector, and it reads 10-15 during startup, but moving it decreases to 0-5 ppm.  In flight (including climb) it's 0 ppm.

[epsalant]

I believe OSHA allows 50 ppm for 40 hr work week

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[Raptor05121]

Where is everyone placing these things?

[Ned Gravel]

CO is lighter than air, not heavier, so somewhere higher (near nose hieight) should be good.  Haven't put mine in yet but that is where I am looking.

[Bob_Belville]

Exposure limits. The carbon monoxide content of the atmosphere in a room, building, vehicle, railcar or any enclosed space shall be maintained at not more than 50 parts per million (ppm) (0.005%) as an eight hour average area level and employees shall be removed from the enclosed space if the carbon monoxide concentration exceeds a ceiling of 100 ppm (0.01%).

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10366

Obviously OSHA standard are quite a bit higher than most of us would be comfortable with. California has lower limits but still far above what I see on my detector and what others are reporting.

ISTM, we're fine until there's a failure of the muffler with the heater on allowing raw exhaust into the cabin.

[nels]

what is the cost of these detectors? Sounds like a good thing to have. I put a color change detector on my dash that is good for a year but honestly don't look at it too often.

[cnoe]

So are we all getting dosed with carbon monoxide when we fly? Or is the meter overly sensitive? 
Are you guys getting those readings with cabin heat on or off?

I'm seeing 0-50+ ppm during startup/taxi depending on wind and 0-1 during flight. That is with the heater both open and closed.

If I was reading 5-20 as some have stated I wouldn't get overly excited but I WOULD start looking for entry points like the rudder boots.

If the level changes appreciably between heater "off" and "on" I'd be very concerned as this might be an early indicator of an exhaust crack.


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[Bob_Belville]

Just now, nels said:

what is the cost of these detectors? Sounds like a good thing to have. I put a color change detector on my dash that is good for a year but honestly don't look at it too often.

There's another thread here - something like Walked Away from Mooney Crash that deals in detail with "real" CO detectors that are under  $100.

 

[1964-M20E]

19 minutes ago, nels said:

what is the cost of these detectors? Sounds like a good thing to have. I put a color change detector on my dash that is good for a year but honestly don't look at it too often.

Nels   here is the link to the other thread that talks about Sensorcon you can have one for about $95 delivered.  There are other options if you want panel mounted.

 

[carusoam]

Nels, this is for you...

The color dot device is similar to navigating using an old VOR Nav radio...  sure, it works pretty well.  You need to stay on top of it more than the modern computer GPS technology...

Best regards,

-a-

Edited March 13, 2017 by carusoam

[nels]

Thanks Gus, I guessed I missed the other thread. I think I'll order one today. CO does concern me and it's nice to be able to monitor what's normal and be able to notice an increasing trend.

[RobertGary1]

The problem with the color dot is you won't notice it until it's too late. When my exhaust cracked I saw a reading of 800. You need that fire alarm going off next to your headset to get your attention. Realistically how many times an hour do you check your stick on dot?

-Robert 

[1964-M20E]

1 hour ago, RobertGary1 said:

The problem with the color dot is you won't notice it until it's too late. When my exhaust cracked I saw a reading of 800. You need that fire alarm going off next to your headset to get your attention. Realistically how many times an hour do you check your stick on dot?

-Robert 

At annual

[Bob_Belville]

I had those color dot things until I bought this 5 star detector over 2 years ago. $84. I'm a happy camper.

https://www.zoro.com/uei-test-instruments-carbon-monoxide-detector-0-to-999-ppm-utlc11/i/G7609996/

[Bob - S50]

Here is a quote from the Pocket CO manual.

"Low levels of CO, typically less than 10 PPM, are not considered especially hazardous, but they do indicate a source of CO.  Sustained levels above 25 PPM for 8 hours, and short-term exposure to more than 125 PPM CO, should be avoided."

[Andy95W]

8 hours ago, Bob - S50 said:

Here is a quote from the Pocket CO manual.

"Low levels of CO, typically less than 10 PPM, are not considered especially hazardous, but they do indicate a source of CO.  Sustained levels above 25 PPM for 8 hours, and short-term exposure to more than 125 PPM CO, should be avoided."

It sounds like 25 ppm at sea level is really no problem.  At 10,000' MSL it could be deadly, or at least affect your alertness and judgement.

[Skates97]

12 hours ago, Raptor05121 said:

Where is everyone placing these things?

Mine is right above my transponder, just to the right of the radio stack. It is right in line of sight as I look over to the MP, FP, RPM so it is just a part of my regular scan now. For mounting I just removed the clip off the back and put a couple strips of velcro on it, hasn't moved at all. I keep meaning to take a picture of it but forget. I will try to remember the next time I'm out at the hangar later this week.

[Seth]

I see a few ppm during taxi sometimes.  I see 1 PPM in rush hour traffic in the car occasionally the first week I had the pocket CO2 detector.

I occasionally formally saw a few PPM when I raise the gear, but after fixing a boot around the rudder one of the pedals.

You most likely have a small CO2 Leak somewhere.  Take off your exhaust, pressurize with air, spray soapy water on it, and see if any bubbles show up anywhere - especially near the welds.  

Could be anywhere, but this is the most common area.  The heater is a shroud around the exhaust manifold that has a pocket of air blow to the cabin.  The heat of the exhaust manifold heats the air that we get in the cabin.  Any leak here is why cabin heat causes CO2 in the cabin easily.  Also, the heat door over time does not seal as well, which means a little heat and thus a little CO2 can seep in when the door is "closed."  This is a serious issue.

My readings, as are most, 0 during most of the flight.  5PPM in flight and especially creeping to 20PPM is not normal. 

-Seth