[Stoves] Stove grates

[Crispin Pemberton-Pigott]

Dear Friends

 

The variability of rebars in terms of carbon content is because they are
usually made from scrap which varies a lot. The carbon content is a
reasonable predictor of their life in a fire.

 

The high tensile deformed (lumpy) bars are going to last longer than the
mild steel round bars because they have more carbon, though it is not a heck
of a lot more. Cast iron has a great deal.

 

In a high carbon environment like a fire, the steel absorbs carbon and gives
it off (strangely enough) depending on the temperature. Cast iron has enough
carbon in it so that it pretty much maintains its crystal structure at high
temperature. The difference between mild steel and cast iron can be shown by
looking at what happens to a thin plate of each when exposed to high
temperature. The mild steel peels off in thin layers over time. Cast iron
does not. The only difference between them is the amount of carbon in it.

 

When it is over 900 C (yellow) mild steel opens its pores, so to speak, and
allows carbon to penetrate at a rate of about 0.1 mm per hour. That is how
case hardening is done. Exposed to air at the same time, the iron is easily
corroded. If it already has a back-up supply of carbon the iron can resist
this corrosion for longer.

 

Cast iron still corrodes if it is kept really hot - it is not magic, it is
just better. Kept hot in an oxidising environment, cast iron also
disappears.

 

Regards

Crispin

 

 

 

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Frans Peeters
Sent: Monday, August 26, 2013 7:34 PM
To: Stoves 
Subject: [Stoves] Stove grates

 

Dear Stovers

 

   Rebars 12x12x700 mm   x15 p.    I used 40 years ago .

 

Later 4mm iron sheet with 5x5 mm holes and 5x5 mm closed spaces ..

 

Now I prefer stainles steel 6 mm woven round wires with 10x10 mm spaces .
350x700 mm . It  supports  the load  6-20 Kg wood .

It last for ever if covered with stainless seeve made of 1 mm thick
stainless  cut in windows 3x6 mm quenced .The later , It last 1 year and
gives white ash protecting partly the grates due it smal size and its
isolation !!

The smal mass dont rob heat as rebars do .

Rebars have no protection by ash isolation .

Rebars  gives carbon loss, no white ash .

 

Alumine  ceramic  plate Al2O3 must be the ideal grate if 10 mm thick and
conical holes and  3X6 mm .open on the top . 4x8 mm under . Spaces 4 mm .

It can be mouldes  as perles for electric heaters have .

 

 

Regards

Frans.

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