[Stoves] Particulate Matter Norms

[Crispin Pemberton-Pigott]

Dear Rajan

 

I bit more investigation shows that it appears to be a number related what
was a common test for smoke density 'back in the day' when PM detection was
very difficult. They are called 'obscuration' meters. A light would shine
across the chimney and if the light was obscured by smoke it was deemed to
be 'smoky'. This later translated into a particulate load that controlled
purely by dilution. If you were emitting too much as a concentration you had
to blow extra air into it to reduce the environmental impact. That later
evolved into total mass emitted.

 

If you find a standard that is based on mass alone, then it is one of those
earlier standards which were based on early attempts to reduce environmental
impact of the 'dosing'. There are many old stove standard based on
obscuration including South Africa's SANS 1111 which is presently up for
consideration for review.

 

These numbers are not translatable into the IWA approach which is based on
either the PM mass emitter per unit of energy released (mg/MJ) or per mass
of fuel burned (a preference in the US where most emissions are mg/kg
burned.

 

The mass per mass burned is not at all convenient for stoves because if you
change fuels (and there are lots of different fuels for stoves) you have to
set different emission rates to be equal to the other fuels. On a mass per
MegaJoule basis you can make comparisons across a spectrum of fuels and
conditions.

 

My earlier comments still stand: the concentration (mass per meter3) has no
meaning if you don't know the number of cubic metres, and the concentration
in a room has no meaning if you don't know both the fuel burn rate and the
rate of air changes per hour. The latter is quite easy to model if you have
the performance of the stove and fuel combination well characterised and you
know the range of air changes you want to investigate.

 

Best regards

Crispin

 

 

Dear Crispin,

 

Bureau of Indian Standards ( BIS ) gives 2 mg/m3 as the upper limit for
particulate matter ( PM ) emissions from a wood stove.

 

Could you please help me with the Norms set by WHO for PM from a wood stove
?  Are the Norms a little more liberal ?

 

Regards,

 

Rajan

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