Measuring CO

[Rich M]

In effect, there is a hot wire which glows incandescent; when the CO (read
combustible gas) comes into contact with it, it in effect 'burns' so heating
the wire further. A constant current is used to maintain the filament
temperature which forces a change in applied voltage when this extra heating
takes place.
Unfortunately, there is interference from other combustible gases present
(notably HC's).
i am sounding deliberately vague here at the moment, we used to make such a
machine, I will try and get a more comprehensive description when I'm next
in the office.

Rich

> -----Original Message-----
> From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
> Behalf Of Jens Knickmeyer
> Sent: 09 July 2000 19:01
> To: Mailinglist DIY_EFI (E-mail)
> Subject: Measuring CO
>
>
> Hi all,
>
> this week a friend of mine bought an old CO tester. The CO sensor
> of that tester consists of two wires, in a way it looks like there are
> two bulbs without glass: the exhaust gas flows through the sensor.
> The first wire is heated with a constant current, the second wire
> is used to measure some current or voltage.
>
> My questions: Does anyone know this method? How does it work, and
> how good is it? Here in Germany, testers to do emissions tests with have
> to use infrared absorbing measurement, so I wonder about the accuracy
> of other methods. Can anybody tell me if building a CO tester working
> according to the method mentioned above is worth the money and time?
>
> Thanks in advance,
>
> Jens
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