[Stoves] CO monitoring seeking practical analogues in local testing methods for the 90% of the rest of us

Crispin Pemberton-Pigott crispinpigott at gmail.com
Fri Oct 22 14:57:54 CDT 2010


Dear Richard

"Whether acoustically powered or calibrated by other sensors, if such can be
used to calibrate for example, a type species of local plant(s), animal(s)
or even simpler, a locally recipe of ordinary chemicals which react to
dangerous concentrations of CO ---as the on site indicator of CO
concentration, THATS what we are looking for."

I am afraid to say it is slightly more complicated than that and I should
say something or people might run too far down a road leading to really bad
information.

The CO level in the emissions is not easy to quantify unless you know how
diluted it is.  CO is not a danger on its own - it is the concentration of
it when breathed that matters. By the time it is breathed, it has been
diluted. How diluted was it when all the gases were passing through the
stove (excess air)? How diluted was it before it was inhaled? 

In order to make a meaningful statement about the relative danger from CO
from a stove - before getting to the point of discussing the dilution
post-stove, we need to know either how efficiently the conversion from C to
CO2 was (which involves absolute measurements of both CO and CO2 while
measuring the mass loss) or we need to know the CO and the dilution.

Worse, we have to know when the CO was emitted because for our purposes
(mostly biomass stoves) the CO emission varies considerably with time - big
time. For a normal improved stove the range of concentration will be 20:1. 

If you have a device that measures the CO level and dilution at one moment,
it tells you nothing about what it will be 10 or 20 minutes later - not even
within 5% of value. 

Even if you had a strip that changed colour slowly with exposure level and
you photographed it every few seconds and had the ability to decode the
colour to calculate the CO concentration get a rate of change up and down
(at least a theoretically possible device) it would not tell you what the
dilution was and thus you still can't work out the total.

We need real time CO and O2, or CO and CO2 (from which the others can
reasonably be calculated).

Regards
Crispin

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