search  current discussion  categories  safety - toxicity 

carbon monoxide poisoning- fresh speculation

updated wed 10 sep 03


iandol on mon 8 sep 03

Dear Earl Krueger,

Thank you for that valuable information. It is not listed in my 77th =
edition of the CRC handbook.

So, lets assume the Carbon Monoxide will burn freely if it is above 650 =
deg Celsius and there is an adequate supply of oxygen. Below that =
temperature even with air present it will not burn and will become a =
hazard to health.

This gives a Dangerous Window of Opportunity for Carbon monoxide to be =
emanating from a kiln once the temperature goes above, lets say, 250 deg =
Celsius. This is because carbonaceous matter such as paper in paper clay =
will inflame at that temperature (Recall F...451, the book?). If =
pyrolysis takes place and gradually reduces the oxygen the reactions =
will change from one where Carbon dioxide dominates to one where Carbon =
monoxide is the dominant gas, if we ignore Nitrogen.

If air is allowed to freely enter the kiln during this period Carbon =
Monoxide will not form because heat from the burning organic matter will =
give the self sustaining chemical reaction Bob Hollis has provided for =
us (thanks Bob ). IF free air is prevented from entering, then organic =
matter in the clay will change to some degree into Carbon Monoxide and =
the paper burning reaction will cease through a lack of Oxygen. But once =
past the 650 Deg C mark this gas should burn provided there is oxygen =

Now, as I recall "We" are instructed to ensure that there is adequate =
ventilation to make sure the body of the clay is not reduced until all =
of the organic matter has been burned. Most important with Iron rich =
clay. So ensure a circulation of air within your electric kilns or make =
sure you have a good supply of secondary air if firing with Hydro Carbon =
fuels (Wood, Gas, Oil).

Have I missed anything out? Does this make sense?=20

The explosion thing seems remote except when firing "Paper Clay"

Thanks for your contribution and best regards,

Ivor Lewis. Redhill, South Australia