CO Levels

[Jim Peace]

You should really get two.  One to check the checker....

It is the best thing you can have in your plane....everything else is just fluff......

[MikeOH]

34 minutes ago, Jim Peace said:

You should really get two.  One to check the checker....

It is the best thing you can have in your plane....everything else is just fluff......

Hmm, which one do you believe if they disagree?  Better buy a THIRD one

[DXB]

For a little perspective, regular smokers can still  have ~10ppm CO in their EXHALED breath an hour after their last cigarette.  I’m not claiming that’s healthy, but at the same time, chasing every little gap in your floor and firewall until your Sensorcon reads 0 on the ground may not be time well spent.  Many of our birds still have ashtrays in the armrests.  If one were to use them, I’d certainly suggest a very insensitive CO monitor 

[1964-M20E]

My sensorcon generally show 0ppm in flight but on the ground it will vary wildly depending on winds and taxiing.  Open the vent window during slow flight or landing on a hot day and CO goes up.

My concern is long term exposure while flying but remember the effect is cumulative thought out the day.  Be aware of your daily exposure since it takes time for the body to rid itself of CO once the CO source has been removed.

[59Moonster]

11 hours ago, MikeOH said:

Hmm, which one do you believe if they disagree?  Better buy a THIRD one

That's funny.

 

Ummm. If you have that much doubt that you need two of them, then maybe you should send it in to be checked. You are supposed to anyways, otherwise they will expire!

[1964-M20E]

45 minutes ago, 59Moonster said:

That's funny.

 

Ummm. If you have that much doubt that you need two of them, then maybe you should send it in to be checked. You are supposed to anyways, otherwise they will expire!

Yeah it is a real thing I have  OAT, and V shown in 2 places on multiple instruments from different manufacturers each showing different values.  When I ask the manufacturer about a calibration procedure they all say no calibration required or possible our instrument is always correct.  

[Jim Peace]

1 hour ago, 59Moonster said:

That's funny.

 

Ummm. If you have that much doubt that you need two of them, then maybe you should send it in to be checked. You are supposed to anyways, otherwise they will expire!

When I decided to buy one I was not really sure how accurate they were so I got two and wanted to see if they came up with he same reading.  Amazingly they are always within single digits of each other and most of the time within 1 or 2 numbers....When I send them in for battery or service I will just keep one in the plane and the other will go with me to work.  Still a good feeling to have two....Now if I could have two engines even better.......

[flyboy0681]

On 1/25/2020 at 11:58 AM, Skates97 said:

I have the sensorcon and often see 10-30 on the ground during run up, especially if the door is open. It will sometimes jump higher than that on climb out but ends up at zero in cruise. Sometimes see it come up on descent as I'm slowing into the pattern. I'll see it around 5-10 just after shutdown. 

I'm not too concerned about a few minutes with the readings on the ground and various phases of flight. If I saw the number move, even 1-2 points, when using cabin heat I would be very concerned and have everything checked before any further flying. In fact anytime I use cabin heat I make note of the reading on the sensorcon before and watch to make sure it doesn't go up. 

Same here.

[59Moonster]

1 hour ago, Jim Peace said:

....Now if I could have two engines even better.......

If only they were as cheap to maintain. 

[flyer338]

The absolute quantity of CO emitted by your engine varies by air/fuel ratio and power setting, and it is fairly easy to calculate. The formula is pounds per hour of fuel multiplied by the A/F ratio, percent CO in the exhaust, equals pounds per hour of CO. Example: at take-off my J shows a fuel flow of 19.6 gph. The fuel (100 LL) weighs 5.82 pounds per gallon. Assuming a full rich A/F ratio of 12:1 (best power)  and percent CO in the exhaust of 6%. The same calculation for cruise (16:1 A/F ratio and 7.5 gph 50 degrees lean of peak). I do not have a fuel flow for lean idle/taxi, but I estimate it as 1 gph. 
And here are the calculated value in lbs./CO per hour: take-off 82, cruise 35, and idle 8.7.

The next part is more difficult to quantify, but based on empirical experience, I suggest the greatest risk for CO in the cockpit is during ground operations; the aircraft speed is low, and airflow into the passenger compartment is likely greatest because Windows and cowl flaps are open. Next is take-off/climb because absolute emissions are greatest, airspeed is relatively slow, and there is a higher deck angle. Lowest is cruise: there is minimum deck angle, windows closed , maximum airflow around the plane and minimum concentration of CO.

The estimated A/F ratios and CO percentages are by memory from my time as a smog technician, oh so long ago.

[carusoam]

Less CO and more CO₂ when running LOP...
 

So if you see a CO alarm, and you go about closing off vents and heat system...also consider going more LOP at the same time...

Having excess O₂ available helps complete the conversion to CO₂...

PP thoughts only, not a physical chemist...

-a-

[Ibra]

On 1/26/2020 at 4:41 PM, ArtVandelay said:

Looks like my muffler has sprung a leak, CO levels pop up for first time, turn heat off and it drops to single digits.

Which part? Do you have a picture? I am taking opportunity to check ours while it is sitting on a table

On the ground in hot days/calm winds, I tend to get high CO readings, bit worrying as I get more when doors & vents are closed, so surely engine/muffler/cabin leaks

Less of it now, as aggressive leaning while taxis in hot days is becoming SOP (no need to check EGT or FF, just lean until that CO detector stops )

[ArtVandelay]

Which part? Do you have a picture? I am taking opportunity to check ours while it is sitting on a table
On the ground in hot days/calm winds, I tend to get high CO readings, bit worrying as I get more when doors & vents are closed, so surely engine/muffler/cabin leaks
Less of it now, as aggressive leaning while taxis in hot days is becoming SOP (no need to check EGT or FF, just lean until that CO detector stops )

AP found the leak by pressure testing, sent it off for repair. No pix.