Does a Modern Car Exhaust System Impact a Carbon Monoxide Detector's Accuracy?

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Discussion Overview

The discussion revolves around the accuracy of a carbon monoxide detector when placed near the exhaust of a modern car, specifically a Honda CRV. Participants explore the implications of modern exhaust systems, including catalytic converters, and their potential impact on carbon monoxide emissions. The conversation includes aspects of detection limits, testing methods, and the chemical processes involved in carbon monoxide production.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant notes that the carbon monoxide detector did not register any CO when placed near the exhaust, questioning whether modern exhaust systems with catalytic converters produce negligible CO or if the detector is inaccurate.
  • Another participant mentions the threshold detection limit of the detector, suggesting it may not have reached the minimum level of 70 ppm required for detection.
  • Some participants discuss the efficiency of modern gasoline engines compared to diesel engines, proposing that newer models emit less CO due to improved combustion processes.
  • There are inquiries about effective methods to test the detector's functionality, with suggestions including using controlled sources of CO, such as burning wood or using gas appliances.
  • A participant describes an experiment with a candle in a closed pot, noting that CO levels increased significantly as oxygen was consumed, prompting questions about the chemical reactions involved in CO production.
  • Another participant clarifies that incomplete combustion leads to CO production rather than a direct conversion of oxygen to CO.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of modern exhaust systems in reducing CO emissions and the accuracy of the carbon monoxide detector. The discussion remains unresolved, with multiple competing perspectives on the topic.

Contextual Notes

Some limitations include the dependence on specific conditions such as ventilation in the parking area and the calibration of the detector. The discussion also highlights the variability in CO emissions based on engine type and combustion efficiency.

jlcd
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https://www.amazon.com/dp/B004Y6V5CI/?tag=pfamazon01-20

I bought the above carbon monoxide detector out of curiosity.. it has over 1,500 positive 5 star reviews. I put it near the exhaust in the mall parking and sit inside for 20 minutes.. but it doesn't seem to detect any carbon monoxide coming from the exhaust. The car is a Honda CRV. Does modern exhaust system have so called catalytic converter that produce almost zero output or is the detector just not accurate enough? But it's supposed to be sensitive to detect minute amount of carbon monoxide. The unit self test seems to work.
 
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Threshold detection limit is ppm; translates as 5-10 ppm.
 
do you mean the threshold detection limit of the car or the detector?
 
Root word: "detect." The automobile doesn't "detect" anything.
 
I actually have this model in my basement. The min detection is 70 ppm. Perhaps it never it never reached that amount.
 
If combustion is good, there should be little to no carbon monoxide. I remember sticking a combustion gas analyzer up the tailpipe of my car to test it (the analyzer) and I think I was getting single digit ppm readings.
 
Greg Bernhardt said:
I actually have this model in my basement. The min detection is 70 ppm. Perhaps it never it never reached that amount.

how do you test if the device is working? A quick limited source of carbon monoxide...
 
jlcd said:
how do you test if the device is working? A quick limited source of carbon monoxide...
Hit the test button and hope regulations insure it works. Kiddie is a well known brand. I wouldn't worry. You should have a carbon monoxide alarm on every house level.
 
jlcd said:
how do you test if the device is working? A quick limited source of carbon monoxide...
... an open fire in your backyard? the exhaust of a domestic boiler when run at maximum power? Most commercial appliances that burn gas are actually quite 'clean' in the sense that they do not produce a lot of CO and NOx, so if you want to test this you should go for an uncontrolled/unoptimized fire like a fireplace, a wood stove or a basket fire (? is it called this? You have an iron basket filled with wood and burn it in your yard). The exhaust of a fireplace produces CO in the order of 1000's, but if all works well, you can only measure this at the end of the chimney.

Fun idea: go to family/friends with a fireplace and scare them witless by measuring the CO levels in their living room. It's not just fun, you could save lives as well..
 
  • #10
I read this in amazon "Though I can't tell how accurate it is, I can confirm it detects CO. It was reading 0 in my apartment then I put it in a large pot with a candle in it. I closed the lid and allowed the candle to burn up all the oxygen and begin creating CO. When I took it out it was reading 132 and over the next few seconds rose up to a peak of 153 before going back down to 0.

The alarm is quite loud and should be able to be heard throughout a small to medium sized house."

Is it true if the oxygen in the air is burned up.. what is left is CO? What is the chemical reactions involved?
 
  • #11
jlcd said:
Is it true if the oxygen in the air is burned up.. what is left is CO?

Not exactly. It rather means when there is not enough oxygen burning produces monoxide instead of dioxide.
 
  • #12
... or, suboxide.
 
  • #13
jlcd said:
https://www.amazon.com/dp/B004Y6V5CI/?tag=pfamazon01-20

I bought the above carbon monoxide detector out of curiosity.. it has over 1,500 positive 5 star reviews. I put it near the exhaust in the mall parking and sit inside for 20 minutes.. but it doesn't seem to detect any carbon monoxide coming from the exhaust. The car is a Honda CRV. Does modern exhaust system have so called catalytic converter that produce almost zero output or is the detector just not accurate enough? But it's supposed to be sensitive to detect minute amount of carbon monoxide. The unit self test seems to work.

Gasoline engine especially new versions are way efficient compared to diesel. This because less viscous fuel (HC-hydrocarbon) contains minimal carbon than hydrogen as compared to diesel. Thus, you would expect less CO emission. Further, is the car park close or open? How many cars were there? You would expect peak reading to happen may be the last mall hours where the gas accumulate if the car park was not well ventilated.

Try to catch an exhaust gas of a diesel engine by a cellophane and put it inside, if it does not read then there must be something wrong with the calibration or the sensor. I pressume that's an IR type of sensor.
 

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