"Jerry" wrote in message
...
In article , John
writes

"Jerry" wrote in message
. ..
I was wondering if anyone can answer a question for me.

I borrowed a flue gas analyser to check my oil boiler efficiency
recently. It seems to be working just fine according to the analyser
but there was one parameter 'smoke number' given on the boiler data
sheet as 0-1 which the analyser didn't test for. Is there a conversion
formula that you can use to get this figure. The analyser provided
figures for flue gas temp, oxygen, carbon dioxide, carbon monoxide and
boiler efficiency.


Most analysers do not give a smoke reading. (A couple of expensive
exceptions) but require the operator to use a Draeger type aspiration pump
with a filter paper in the flow path of the flue products. A chemical test
set such as a Brigon or a Fyrite contains the appropriate piece of kit. to
use it you put the sample tube into the flue sample point and draw five
full
strokes of the pump through it to give the required volume pass. the
filter
paper is then removed and the sample "spot" on the paper compared\with
standard colour samples designated on a scale known as Baccarach number.
electronic samplers exist but suffer from smoke/soot deposits on the
sampling optics

What figures did you get btw?


Hi

Do heating engineers normally do a smoke test when they test the flue
gas?

When dealing with oil boilers this is the first test you do! Drawing soot
particles into an analyser "is a very bad thing" and results in rapid
failure of the cell.


The results I got we

Ambient temp 25.1 deg C
Flue gas temp: 159.2 deg C
Oxygen: 4.6%
Carbon monoxide: 10 ppm
Carbon dioxide: 12.1%
Poison index: .0001 Rat (whatever that is)
Gross efficiency: 87.8%
Net efficiency: 93.1%
Carbon monoxide undiluted: 13 ppm (whatever that is)

The data sheet for the boiler only gives the following values:
Smoke No 0-1, CO2 12%, Approx flue gas temp: 165 deg C


The only figures of note are those which the boiler makers give examples of.
As you will see from your results the others are either simple indicators
(useful ones though) or have very low levels as in the carbon monoxide
reading (ppm = parts per million). CO is very low with pressure jet burners
as incomplete/unsatisfactory combustion results in soot rather than CO hence
the smoke reading test.