safe CO levels

[dominikos]

influenced by some of the discussions, I replaced a home CO detector with Sensorcon and went for a quick local flight to enjoy the weather and the plane. Till now I used some residential CO sensor and Sentry. Both of them showed 0. Sensorcon showed 10 when I closed the vents, we have lower temps even in Texas . I checked manual and 10 seemed to be acceptable level. 

Something didn’t feel right - I felt slightly light headed but then blamed being short of sleep. When I open the vents, the number went down to 2. With vents closed, back to 10. And then when landing, the numbers went up to 18. Decided to do another take off / landing. Same situation, but on take off with max power, number goes to 29, drops to 10 in pattern, goes higher on final and drops below 10 on idle. 

Is that normal? Both sentry and home sensor don’t detect anything. What levels do you guys see with this sensor? Could it be coincidence that an engine problem just showed up when I put the sensor in (lucky me) or because I closed the vents?

Thanks, Dominik

 

[EricJ]

It's pretty typical.   Many people see higher numbers at higher angle of attack, and lowest, often zero, at cruise.   You can get an assistant to move the Sensorcon around the cabin and see if you can locate the leaks.   The floor is a pretty typical place to need to tape up holes, etc.    Mine seems to vary day to day, so unless it gets crazy high and stays there I'm not too worried.   Mine has actually alarmed a few times, always in landing configuration at fairly high AoA, and it's always cleared up by the time I'm on the ground.   Hasn't done it in quite a while, though.

FWIW, those numbers are still pretty low compared to allowed levels from places like OSHA.

 

[A64Pilot]

So far my Sensorcom hasn’t moved off of zero, and I did have cabin heat on.

I know it works because I can breathe on it and it will indicate 1 or 2. Yes we breathe out CO as well as CO2, unsurprisingly smokers have higher levels of CO.

One thing odd, my cabin heat doesn’t blow much cowl flaps open, close them and it does, is this a Mooney thing?

[PT20J]

CO is an intermediate product of combustion created when a rich mixture does not completely react to produce carbon dioxide and water. So, CO production is maximum at full rich takeoff power and minimum when running LOP where the excess oxygen reacts with (almost) all the hydrocarbons.

Skip

 

[Ragsf15e]

Those numbers are typical.  I had an exhaust leak and saw 50-60 on the ground and 25ish in cruise.  Normally 15 on the ground and 0 in cruise.  If the wind is blowing the right way you might see a high number on the ground, say 50, but turn into the wind and it drops quickly.

The osha standards are what the home sensors are based on and they are very high.  They won’t alarm or indicate anything until you have a certain level for a specified amount of time.  Say, 100ppm for 8 hours or 300ppm for 10 minutes (that’s a ballpark).  That’s why your sensorcon is a lot more useful.

[A64Pilot]

I believe but may be mistaken that we are more susceptible to CO at altitude.

[WAFI]

6 minutes ago, A64Pilot said:

I believe but may be mistaken that we are more susceptible to CO at altitude.

Yes, your correct! Your more susceptible to CO at altitude because you have less O2 at altitude. CO binds to hemoglobin easier than O2, meaning that free floating O2 has nowhere to go.

Side Note: Supplemental O2 is only beneficial if your in a Oxygen depleted environment. It has no benefit other than maybe a placebo effect on the ground or after a CO exposure.  

[WAFI]

P.S. -  Those little SpO2 or Pulse Oximeter you see people use or even install in there planes are not as accurate as you might think. More like they can be very mis leading and I would say more harmful than beneficial. 

SpO2 machines detect the saturation of your Hemoglobin. The misleading part is that most people think that O2 is the only thing that attaches to Hemoglobin so when you see a 99% saturation you think, yay I'm a OK! I'm full of Oxygen! On the other hand your Hemoglobin just might be saturated with CO rather than O2. 

FACT- A freshly dead human who fell asleep in his car in the garage with the door closed will have a 100% SpO2 reading with hardly any O2 in the body. I apologize for getting graphic. 

A multi meter that fireman carry is probably the best tool you can have. It shows CO, O2, LEL combustable gases. So, true O2 levels of the aircraft at altitude, meaning don't waste your supplemental O2 if your don't have to. CO level which we just covered and LEL maybe you have a fuel leak. Not to mention it also has H2S reading incase you transport stuff like fertilizer.

 

[1980Mooney]

CO+Levels_Risk+Chart.pdf (squarespace.com)

16 hours ago, dominikos said:

influenced by some of the discussions, I replaced a home CO detector with Sensorcon and went for a quick local flight to enjoy the weather and the plane. Till now I used some residential CO sensor and Sentry. Both of them showed 0. Sensorcon showed 10 when I closed the vents, we have lower temps even in Texas . I checked manual and 10 seemed to be acceptable level. 

Something didn’t feel right - I felt slightly light headed but then blamed being short of sleep. When I open the vents, the number went down to 2. With vents closed, back to 10. And then when landing, the numbers went up to 18. Decided to do another take off / landing. Same situation, but on take off with max power, number goes to 29, drops to 10 in pattern, goes higher on final and drops below 10 on idle. 

Is that normal? Both sentry and home sensor don’t detect anything. What levels do you guys see with this sensor? Could it be coincidence that an engine problem just showed up when I put the sensor in (lucky me) or because I closed the vents?

Thanks, Dominik

 

Avweb recommends no more than 35 ppm.  

Carbon Monoxide Detectors (avweb.com)

[Ragsf15e]

27 minutes ago, 1980Mooney said:

CO+Levels_Risk+Chart.pdf (squarespace.com)

Avweb recommends no more than 35 ppm.  

Carbon Monoxide Detectors (avweb.com)

Another good reason to use a quality detector.

Home ones won’t detect at that level.

 

from OSHA website:

What are the OSHA standards for CO exposure?
• The OSHA PEL for CO is 50 parts per million (ppm). OSHA standards prohibit worker exposure to more than 50 parts of CO gas per million parts of air averaged during an 8-hour time period.
• The 8-hour PEL for CO in maritime operations is also 50 ppm. Maritime workers, however, must be removed from exposure if the CO concentration in the atmosphere exceeds
100 ppm. The peak CO level for employees engaged in Ro-Ro operations (roll-on roll- off operations during cargo loading and unloading) is 200 ppm.

[ilovecornfields]

2 hours ago, BumpyAcorn said:

P.S. -  Those little SpO2 or Pulse Oximeter you see people use or even install in there planes are not as accurate as you might think. More like they can be very mis leading and I would say more harmful than beneficial. 

SpO2 machines detect the saturation of your Hemoglobin. The misleading part is that most people think that O2 is the only thing that attaches to Hemoglobin so when you see a 99% saturation you think, yay I'm a OK! I'm full of Oxygen! On the other hand your Hemoglobin just might be saturated with CO rather than O2. 

FACT- A freshly dead human who fell asleep in his car in the garage with the door closed will have a 100% SpO2 reading with hardly any O2 in the body. I apologize for getting graphic. 

A multi meter that fireman carry is probably the best tool you can have. It shows CO, O2, LEL combustable gases. So, true O2 levels of the aircraft at altitude, meaning don't waste your supplemental O2 if your don't have to. CO level which we just covered and LEL maybe you have a fuel leak. Not to mention it also has H2S reading incase you transport stuff like fertilizer.

 

I’m not even sure where to start here, there’s so much to comment on so I’ll start with the one statement that is true - most pulse oximeters can’t differentiate between O2 and CO so if you are in an environment with high levels of CO your SpO2 reading will be falsely elevated. There are co-oximeters that will give you both readings which we use in the hospital to screen for CO poisoning but they are expensive and there’s no point in having one in your plane since you know exactly what the CO levels are.

i think almost everything else in that post was wrong or misleading. Pulse oximeters are definitely not “more harmful than beneficial.” Anytime you take an action based on a test result you need to understand the characteristics and limitations of that test. Pulse oximeters are great at letting you know your oxygen levels, when to use oxygen and how much to use. Yes, they will give you inaccurate readings when CO levels are high but since we all have sensitive CO indicators in our planes we will know when CO levels are high and at that point your pulse ox reading is not your concern - getting on the ground is! We’ve discussed this several times before on MooneySpace.

FACT- a freshly dead human who fell asleep in their car from CO poisoning will NOT have ANY SpO2 reading because they have no pulse! No pulse = no pulse ox reading. Whoever came up with that 100% SpO2 reading has a fundamental lack of understanding about how a pulse oximeter works.

Please, everyone. Stop doing your “research” while sitting on the toilet with your smartphones while lamenting the lack of fiber in your diet. Talk to medical professionals about medical issues and don’t get your medical facts from random people on the internet.

Edited November 6, 2021 by ilovecornfields

[jaylw314]

3 hours ago, BumpyAcorn said:

Side Note: Supplemental O2 is only beneficial if your in a Oxygen depleted environment. It has no benefit other than maybe a placebo effect on the ground or after a CO exposure.  

This is dangerously incorrect misinformation.  I suspect you are basing this on the inadequate knowledge that carbon monoxide irreversibly binds to hemoglobin--it does, but that is irrelevant to oxygen treatment.  If you are still alive, not all your hemoglobin is bound to CO, and it's urgently necessary to maximize the oxygen transport by the remaining hemoglobin, as well as oxygen dissolve in water (which becomes significant with supplemental O2).

Maximum oxygen intake is both the urgent and long-term treatment for carbon monoxide poisoning.  Cranking up your O2 the highest practical flow may buy you a few extra minutes of life, and getting medical care for continuous oxygen treatment is urgent.  To imply otherwise is irresponsible.

[ilovecornfields]

16 minutes ago, jaylw314 said:

This is dangerously incorrect misinformation.  I suspect you are basing this on the inadequate knowledge that carbon monoxide irreversibly binds to hemoglobin--it does, but that is irrelevant to oxygen treatment.  If you are still alive, not all your hemoglobin is bound to CO, and it's urgently necessary to maximize the oxygen transport by the remaining hemoglobin, as well as oxygen dissolve in water (which becomes significant with supplemental O2).

Maximum oxygen intake is both the urgent and long-term treatment for carbon monoxide poisoning.  Cranking up your O2 the highest practical flow may buy you a few extra minutes of life, and getting medical care for continuous oxygen treatment is urgent.  To imply otherwise is irresponsible.

@jaylw314, thanks for pointing that out. There was so much other “stuff” in that post to muck through that I completely missed this one.

100% agree. The treatment for CO poisoning is to get as much oxygen as possible as soon as possible. In severe cases where 100% oxygen at 1 ATM is insufficient, we send people for HBO (hyperbaric oxygen therapy) in a dive chamber. This is the standard of care and not doing so can lead to irreversible brain damage.

[WAFI]

I second that! Great opinion… “Please, everyone. Stop doing your “research” while sitting on the toilet with your smartphones while lamenting the lack of fiber in your diet. Talk to medical professionals about medical issues and don’t get your medical facts from random people on the internet.” — I’m not going to get into what my medical background is.

My opinion— It’s far better to know what your aircrafts ambient cockpit O2 level is so you can supplement with O2 if needed or not, rather than just blindly plugging in. Let’s just use plan old common sense, low SpO2 level in your body is do to a lack of O2 in your blood stream. Lack of O2 in your blood stream is do to lack of O2 in the cabin an obviously because of the lack of O2 at altitude. I hope we can agree on that.

Wouldn’t you rather know ahead of time that the O2 levels are dropping in your aircraft and then start your supplemental O2 or lower your flight level? Rather than wait until your perfectly manicured, thin skin, non callused, non painted, warm, with perfectly perfusion finger tells you that you need O2? I rather forgo the headache and risk of being hypoxic but that’s just me. You might say the rule is to start supplementing prior to getting to O2 depleted flight levels. If thats the case why in the world do you in a PlusOx? The reality is people rely on what that little number says to tell them if they need to start using O2 because they do want to waste there valuable O2, if they don’t need it. 

The next time your around your friend with a PlusOx at sea level, see if all four or five of you have the same readings. Then wonder what all of the readings would be at altitude. Do you go off the guy with the lowest number and let him or her dictate the need for O2? 

Just thoughts here… have fun and be safe!

[exM20K]

1 hour ago, BumpyAcorn said:

My opinion— It’s far better to know what your aircrafts ambient cockpit O2 level is so you can supplement with O2 if needed or not, rather than just blindly plugging in. Let’s just use plan old common sense, low SpO2 level in your body is do to a lack of O2 in your blood stream. Lack of O2 in your blood stream is do to lack of O2 in the cabin an obviously because of the lack of O2 at altitude. I hope we can agree on that.

I care quite a bit more about my SpO2 than the ambient O2 level.  Different people perform differently in the same environment. 
I also care quite a bit about determining what my hypoxia symptoms are and being able to identify them before losing the ability to react.

Supplemental O2 is cheap.  The pulse demand systems and boom cannulas are comfortable.  It’s really no burden to use them above 10,000 which is where my levels start to really fall off.

-dan

[ilovecornfields]

3 hours ago, BumpyAcorn said:

I second that! Great opinion… “Please, everyone. Stop doing your “research” while sitting on the toilet with your smartphones while lamenting the lack of fiber in your diet. Talk to medical professionals about medical issues and don’t get your medical facts from random people on the internet.” — I’m not going to get into what my medical background is.

My opinion— It’s far better to know what your aircrafts ambient cockpit O2 level is so you can supplement with O2 if needed or not, rather than just blindly plugging in. Let’s just use plan old common sense, low SpO2 level in your body is do to a lack of O2 in your blood stream. Lack of O2 in your blood stream is do to lack of O2 in the cabin an obviously because of the lack of O2 at altitude. I hope we can agree on that.

Wouldn’t you rather know ahead of time that the O2 levels are dropping in your aircraft and then start your supplemental O2 or lower your flight level? Rather than wait until your perfectly manicured, thin skin, non callused, non painted, warm, with perfectly perfusion finger tells you that you need O2? I rather forgo the headache and risk of being hypoxic but that’s just me. You might say the rule is to start supplementing prior to getting to O2 depleted flight levels. If thats the case why in the world do you in a PlusOx? The reality is people rely on what that little number says to tell them if they need to start using O2 because they do want to waste there valuable O2, if they don’t need it. 

The next time your around your friend with a PlusOx at sea level, see if all four or five of you have the same readings. Then wonder what all of the readings would be at altitude. Do you go off the guy with the lowest number and let him or her dictate the need for O2? 

Just thoughts here… have fun and be safe!

I actually wish you would go into your medical background because you’re really confusing some pretty fundamental concepts.

The O2 level in the cockpit is completely irrelevant for the exact reason you mentioned in your post - everyone has different physiology. If my SpO2 is 88% and my son’s is 96% then I need supplemental oxygen and he would not be likely to benefit from it. It’s not about “wasting” oxygen it’s about titrating a medical therapy to a clinically relevant endpoint (which is something I do every day at work).

I appreciate you have a little knowledge on the subject and are eager to share, but please consider that not everyone has the background and ability to differentiate between the well meaning and misinformed, malicious and intentionally misleading, and accurate medical information (as we’ve proven in the last 20 months).

With all due respect, if you don’t know what you’re talking about then please keep it to yourself. No one needs this right now.

There’s a reason we monitor cockpit CO levels and individual SpO2 levels. As one of my son’s t shirts says (available for purchase at his Etsy store) “I can explain it to you, but I can’t understand it for you.”

Edited November 7, 2021 by ilovecornfields

[aviatoreb]

5 minutes ago, ilovecornfields said:

As one of my son’s t shirts says (available for purchase at his Etsy store) “I can explain it to you, but I can’t understand it for you.”

Wow - your son is deep.  He could be the next Yogi Berra.

[DXB]

On 11/5/2021 at 7:14 PM, dominikos said:

influenced by some of the discussions, I replaced a home CO detector with Sensorcon and went for a quick local flight to enjoy the weather and the plane. Till now I used some residential CO sensor and Sentry. Both of them showed 0. Sensorcon showed 10 when I closed the vents, we have lower temps even in Texas . I checked manual and 10 seemed to be acceptable level. 

Something didn’t feel right - I felt slightly light headed but then blamed being short of sleep. When I open the vents, the number went down to 2. With vents closed, back to 10. And then when landing, the numbers went up to 18. Decided to do another take off / landing. Same situation, but on take off with max power, number goes to 29, drops to 10 in pattern, goes higher on final and drops below 10 on idle. 

Is that normal? Both sentry and home sensor don’t detect anything. What levels do you guys see with this sensor? Could it be coincidence that an engine problem just showed up when I put the sensor in (lucky me) or because I closed the vents?

Thanks, Dominik

 

Getting back to the original question here before this thread had to shift to correcting misunderstandings of cardiopulmonary physiology.

10ppm in flight in and of itself should be no big deal, though admittedly its impact on hemoglobin oxygen delivery to tissue would increase as altitude goes up in a way that the OSHA standard levels don't fully capture.  I originally didn't want a Sensorcon specifically because I didn't want to know about levels that low getting into the cockpit in flight - it provides a meaningless number as a source of stress without detecting real hazard.  One could reasonably look for small gaps in the firewall and cabin floor that could be sealed easily based on that information, but those gaps aren't ever likely to become really dangerous.

I've changed my opinion a bit after the experience of @AlexLev.  He saw very low levels in the cockpit with the heat on, but his baseline with heat off was zero in flight. I told him to blow it off (pun intended?).  Investigating further led to him finding a minute hole in his muffler leaking into the heat shroud - that tiny hole could have grown rapidly to become seriously life threatening in a hurry on a cold winter flight. It was a good early catch that was facilitated by the high sensitivity of the Sensorcon.   I think the bottom line is that low levels are acceptable in cruise and perhaps inevitable on the ground.  However, any increase upon turning on the heat warrants close inspection of the muffler.  

Edited November 7, 2021 by DXB

[Ragsf15e]

24 minutes ago, DXB said:

Getting back to the original question here before this thread had to shift to correcting misunderstandings of cardiopulmonary physiology.

10ppm in flight in and of itself should be no big deal, though admittedly its impact on hemoglobin oxygen delivery to tissue would increase as altitude goes up in a way that the OSHA standard levels don't fully capture.  I originally didn't want a Sensorcon specifically because I didn't want to know about levels that low getting into the cockpit in flight - it provides a meaningless number as a source of stress without detecting real hazard.  One could reasonably look for small gaps in the firewall and cabin floor that could be sealed easily based on that information, but those gaps aren't ever likely to become really dangerous.

I've changed my opinion a bit after the experience of @AlexLev.  He saw very low levels in the cockpit with the heat on, but his baseline with heat off was zero in flight. I told him to blow it off.  Investigating further led to him finding a minute hole in his muffler leaking into the heat shroud - that tiny hole could have grown rapidly to become seriously life threatening in a hurry on a cold winter flight. It was a good early catch that was facilitated by the high sensitivity of the Sensorcon.   I think the bottom line is that low levels are acceptable in cruise and perhaps inevitable on the ground.  However, any increase upon turning on the heat warrants close inspection of the muffler.  

Yep, definitely agree, it’s about changes from your baseline.

I had a totally disconnected exhaust riser and the level went up, but by itself wasn’t really worrying in flight (my firewall is well sealed?).  But my normal cruise had been 0.  And it had doubled on the ground.  It was the change that had me taking off the cowling and looking close.

[DXB]

15 minutes ago, Ragsf15e said:

Yep, definitely agree, it’s about changes from your baseline.

I had a totally disconnected exhaust riser and the level went up, but by itself wasn’t really worrying in flight (my firewall is well sealed?).  But my normal cruise had been 0.  And it had doubled on the ground.  It was the change that had me taking off the cowling and looking close.

Yup - I should have added any significant change from baseline (even at "safe" levels) for a given flight condition should warrant close inspection of the entire exhaust, not just the muffler.

Also @PT20J makes an important point regarding much more CO at rich mixtures.  The graph below is the best I could find to illustrate.  Mixture changes obviously have a big impact while ROP, so it's not alarming for the baseline to be higher at takeoff and after GUMPS. Below a stoichiometric mixture, the curve flattens out significantly, but there are still potentially threatening levels of CO produced at even the leanest combustible mixture, so being deep LOP does not assure safety.

 

Edited November 7, 2021 by DXB

[WAFI]

6 hours ago, ilovecornfields said:

I actually wish you would go into your medical background because you’re really confusing some pretty fundamental concepts.

The O2 level in the cockpit is completely irrelevant for the exact reason you mentioned in your post - everyone has different physiology. If my SpO2 is 88% and my son’s is 96% then I need supplemental oxygen and he would not be likely to benefit from it. It’s not about “wasting” oxygen it’s about titrating a medical therapy to a clinically relevant endpoint (which is something I do every day at work).

I appreciate you have a little knowledge on the subject and are eager to share, but please consider that not everyone has the background and ability to differentiate between the well meaning and misinformed, malicious and intentionally misleading, and accurate medical information (as we’ve proven in the last 20 months).

With all due respect, if you don’t know what you’re talking about then please keep it to yourself. No one needs this right now.

There’s a reason we monitor cockpit CO levels and individual SpO2 levels. As one of my son’s t shirts says (available for purchase at his Etsy store) “I can explain it to you, but I can’t understand it for you.”

Let me get one thing straight for you— No one is trying to be malicious or misinformed people here. If you would like I would happily willing to talk further over the phone but not to debate, just discuss in detail. I’m a very open minded and caring person. Your choice? Oh, I’ll even fill you in on my back ground. 

 

 

[Guest]

12 hours ago, BumpyAcorn said:

I second that! Great opinion… “Please, everyone. Stop doing your “research” while sitting on the toilet with your smartphones while lamenting the lack of fiber in your diet. Talk to medical professionals about medical issues and don’t get your medical facts from random people on the internet.” — I’m not going to get into what my medical background is.

My opinion— It’s far better to know what your aircrafts ambient cockpit O2 level is so you can supplement with O2 if needed or not, rather than just blindly plugging in. Let’s just use plan old common sense, low SpO2 level in your body is do to a lack of O2 in your blood stream. Lack of O2 in your blood stream is do to lack of O2 in the cabin an obviously because of the lack of O2 at altitude. I hope we can agree on that.

Wouldn’t you rather know ahead of time that the O2 levels are dropping in your aircraft and then start your supplemental O2 or lower your flight level? Rather than wait until your perfectly manicured, thin skin, non callused, non painted, warm, with perfectly perfusion finger tells you that you need O2? I rather forgo the headache and risk of being hypoxic but that’s just me. You might say the rule is to start supplementing prior to getting to O2 depleted flight levels. If thats the case why in the world do you in a PlusOx? The reality is people rely on what that little number says to tell them if they need to start using O2 because they do want to waste there valuable O2, if they don’t need it. 

The next time your around your friend with a PlusOx at sea level, see if all four or five of you have the same readings. Then wonder what all of the readings would be at altitude. Do you go off the guy with the lowest number and let him or her dictate the need for O2? 

Just thoughts here… have fun and be safe!

I’m sure before medical school you took some English studies and spelling.  Do and due have different meaning but the same pronunciation, or were you low on O2 while typing?

Clarence

[Jmaldon6]

I’m a paramedic and I’ll just share the CO PPM numbers I go with. Of course everyone may handle CO Exposure differently but here’s mine:

35ppm - start troubleshooting and closely monitor
100ppm - Stop the flight and land as soon as reasonable
300ppm - emergency, land ASAP closest field

I place this on a small label on the CO monitor

[jaylw314]

1 hour ago, BumpyAcorn said:

Let me get one thing straight for you— No one is trying to be malicious or misinformed people here. If you would like I would happily willing to talk further over the phone but not to debate, just discuss in detail. I’m a very open minded and caring person. Your choice? Oh, I’ll even fill you in on my back ground. 

No one is accusing you of trying to be malicious or intentionally misinforming people.  That would be the definition of "disinformation."  Misinformation is unintentionally providing incorrect information, which is something people do with the best of intention all the time.

Even if it means nothing negative about the character of the person providing it, misinformation can still be dangerous, though.  

[Ragsf15e]

16 minutes ago, Jmaldon6 said:

I’m a paramedic and I’ll just share the CO PPM numbers I go with. Of course everyone may handle CO Exposure differently but here’s mine:

35ppm - start troubleshooting and closely monitor
100ppm - Stop the flight and land as soon as reasonable
300ppm - emergency, land ASAP closest field

I place this on a small label on the CO monitor

These seem reasonable, but you should typically see 0 in cruise.  If I suddenly saw a significant change from that, say more than about 20 (especially with the heat on), I’d be terminating the flight.  I’d know something changed for the worse.

I guess I’d consider your numbers reasonably safe from a human health perspective, but you can probably use lower numbers for an airplane health perspective.