On Sat, 19 Nov 2005 17:37:05 +0000, Chris Hogg wrote:

I have a gas-fired pottery kiln.

Propane _is_ LPG. OK, so is butane. But the stuff in the big static
tanks is just the same as in the orange propane cylinders.

Also LPG firing for a kiln is relatively insensitive to jet size and
more sensitive to carburation by adjusting the airflow into the burner.
You'll have to tweak it, but it will still work fine on the same jet.

PS - Get a mains-powered CO meter too. I use an LPG fired kiln and if
we don't ventilate properly the CO levels can get worryingly high. It's
worth monitoring this.

"Andy Dingley" wrote in message
...

PS - Get a mains-powered CO meter too. I use an LPG fired kiln and if
we don't ventilate properly the CO levels can get worryingly high. It's
worth monitoring this.


Its worth getting it checked as it shouldn't produce CO in significant
quantities.

On Sun, 20 Nov 2005 20:16:32 GMT, "dennis@home"
wrote:

Its worth getting it checked as it shouldn't produce CO in significant
quantities.

It's a kiln, not a CH boiler. They always produce CO - sometimes
deliberately.

"Andy Dingley" wrote in message
...
On Sun, 20 Nov 2005 20:16:32 GMT, "dennis@home"
wrote:

Its worth getting it checked as it shouldn't produce CO in significant
quantities.

It's a kiln, not a CH boiler. They always produce CO - sometimes
deliberately.



However you read it CO means incomplete combustion. I do realise that
firing certain materials may produce undesirable products of combustion. In
this event an interlocked extract system would be the way to deal with the
issues

On Mon, 21 Nov 2005 17:09:26 +0000 (UTC), "John"
wrote:

However you read it CO means incomplete combustion.

Yes, we like that. It's what makes the glazes work.

"Andy Dingley" wrote in message
...
On Mon, 21 Nov 2005 17:09:26 +0000 (UTC), "John"
wrote:

However you read it CO means incomplete combustion.

Yes, we like that. It's what makes the glazes work.


The glazes work in an electric kiln where no CO is produced.

On Mon, 21 Nov 2005 20:25:14 GMT, "dennis@home"
wrote:

However you read it CO means incomplete combustion.

Yes, we like that. It's what makes the glazes work.

The glazes work in an electric kiln where no CO is produced.

Not all of them.

"Andy Dingley" wrote in message
...
On Mon, 21 Nov 2005 20:25:14 GMT, "dennis@home"
wrote:

However you read it CO means incomplete combustion.

Yes, we like that. It's what makes the glazes work.

The glazes work in an electric kiln where no CO is produced.

Not all of them.


They all glaze.
Only the colour changes.

You do know that incomplete burning of propane to produce CO also produces
the same amount of hydrogen which could blow your place to bits.

Does the fire authority know you carry out such a potentially dangerous
operation?

On Mon, 21 Nov 2005 21:12:09 GMT, "dennis@home"
wrote:

You do know that incomplete burning of propane to produce CO also produces
the same amount of hydrogen which could blow your place to bits.

Does the fire authority know you carry out such a potentially dangerous
operation?

Oh _do_ **** off you Blairite bedwetter

"AJH" wrote in message
...
On Mon, 21 Nov 2005 21:12:09 GMT, "dennis@home"
wrote:

You do know that incomplete burning of propane to produce CO also produces
the same amount of hydrogen which could blow your place to bits.

Nope, it's the Hydrogen grabbing the oxygen molecules first that only
leaves enough to form CO or soot for the reducing atmosphere. Now if
you keep everything hot enough you can produce syngas which is CO + H2
and this is the basis for many synthetic chemicals but with air I
think the free ride given to N2 cuts temperatures below an equilibrium
that favours syngas.


C3H8 + 4(O2+4N2) === CO + 2CO2 + 3H2O + H2 + 16 N2

"Andy Dingley" wrote in message
...
On Mon, 21 Nov 2005 21:12:09 GMT, "dennis@home"
wrote:

You do know that incomplete burning of propane to produce CO also produces
the same amount of hydrogen which could blow your place to bits.

Does the fire authority know you carry out such a potentially dangerous
operation?

Oh _do_ **** off you Blairite bedwetter


Its got nothing to do with Blair.
Its consideration for others.

On Mon, 21 Nov 2005 18:24:52 +0000, Andy Dingley wrote:

On Mon, 21 Nov 2005 17:09:26 +0000 (UTC), "John"
wrote:

However you read it CO means incomplete combustion.

Yes, we like that. It's what makes the glazes work.

Reducing atmosphere and all that jazz. Takes the oxygen out of oxides

On Mon, 21 Nov 2005 21:12:09 GMT, dennis@home wrote:

"Andy Dingley" wrote in message
...
On Mon, 21 Nov 2005 20:25:14 GMT, "dennis@home"
wrote:

However you read it CO means incomplete combustion.

Yes, we like that. It's what makes the glazes work.

The glazes work in an electric kiln where no CO is produced.

Not all of them.


They all glaze.
Only the colour changes.

You do know that incomplete burning of propane to produce CO also produces
the same amount of hydrogen which could blow your place to bits.

Does the fire authority know you carry out such a potentially dangerous
operation?

Very unlikely. The hydrogen has a far greater affinity for the oxygen than
the carbon.

The message
from The Natural Philosopher contains these words:

You do know that incomplete burning of propane to produce CO also
produces
the same amount of hydrogen which could blow your place to bits.

Does the fire authority know you carry out such a potentially dangerous
operation?

Very unlikely. The hydrogen has a far greater affinity for the oxygen than
the carbon.

So how accurate is the formula dennis@home previously stated?

"C3H8 + 4(O2+4N2) === CO + 2CO2 + 3H2O + H2 + 16 N2"

I am no chemist but ISTM that that could equally well be written as:

C3H8 + 4(O2+4N2) === 2CO + CO2 + 4H2O + 16 N2

--
Roger Chapman

"Roger" wrote in message
k...
The message
from The Natural Philosopher contains these words:

You do know that incomplete burning of propane to produce CO also
produces
the same amount of hydrogen which could blow your place to bits.

Does the fire authority know you carry out such a potentially dangerous
operation?

Very unlikely. The hydrogen has a far greater affinity for the oxygen
than
the carbon.

So how accurate is the formula dennis@home previously stated?

"C3H8 + 4(O2+4N2) === CO + 2CO2 + 3H2O + H2 + 16 N2"

I am no chemist but ISTM that that could equally well be written as:

C3H8 + 4(O2+4N2) === 2CO + CO2 + 4H2O + 16 N2


That would be correct if there were an ample supply of oxygen.
There isn't so you get the CO and the H2 produced.
The CO reduces the oxides in the glaze (changing the colours).
The hydrogen is left over AFAICT.
This is what may cause an explosion.

On Thu, 24 Nov 2005 19:20:26 GMT, "dennis@home"
wrote:

The hydrogen is left over AFAICT.
This is what may cause an explosion.

Ever watched a Space Shuttle launch ? Ever noticed the giant cigarette
lighter burning away beneath it, spewing sparks at the main engines?
It's there to _prevent_ explosions.

An explosion is caused when you take an appreciable quantity of unburned
fuel, mix it with a quantity of unreacted oxidiser (or air) and _then_
cause ignition of it. If you flare both constituents off continuously
then there's no build-up and no risk of explosion.

Not surprisingly, having a honking great kiln burner running in close
proximity along with a kiln inner that's glowing red will have a similar
effect to NASA's sparkler. Although there's all manner of chemistry
going on, and all manner of potential fuels being reduced out of their
previously combined forms, then these "explosive" fuels are continually
and _safely_ burned away as fast as they're formed. Maybe this doesn't
happen inside the kiln (in fact it's one reason why a kiln exhaust vent
will _always_ have a prominent exhaust flame) but your nannying over
terrible explosion risks is inaccurate and ridiculous.

I think you must have mis-interpreted the "hydrogen bomb" in your Bert
the Turtle cartoons.

"Andy Dingley" wrote in message
...

I think you must have mis-interpreted the "hydrogen bomb" in your Bert
the Turtle cartoons.

Don't talk about hydrogen bombs when you don't know how to make one.
Hint; don't use hydrogen.

The message
from "dennis@home" contains these words:

Very unlikely. The hydrogen has a far greater affinity for the oxygen
than
the carbon.

So how accurate is the formula dennis@home previously stated?

"C3H8 + 4(O2+4N2) === CO + 2CO2 + 3H2O + H2 + 16 N2"

I am no chemist but ISTM that that could equally well be written as:

C3H8 + 4(O2+4N2) === 2CO + CO2 + 4H2O + 16 N2


That would be correct if there were an ample supply of oxygen.
There isn't so you get the CO and the H2 produced.
The CO reduces the oxides in the glaze (changing the colours).
The hydrogen is left over AFAICT.
This is what may cause an explosion.

I was pondering TNPs remark on Hydrogen having a much greater affinity
to hydrogen in a reducing atmosphere. If there was an ample supply of
oxygen surely there would be no CO produced.

--
Roger Chapman

"Chris Hogg" wrote in message
...

Firing a gas kiln in reduction requires knowledge and experience of
both the potting/firing processes and the appropriate hazards and
safety precautions. While I wouldn't claim that no potter ever gets it
wrong, I suspect that serious accidents are rare.


They happen often enough for the HSE to take an interest.

http://www.hse.gov.uk/lau/lacs/27-10.htm

an extract of which reads




Adequate combustion air should be available; grilles or cages over inlets
should not be restricted or blocked and the room where the kiln is sited
should be adequately vented



IANAL but I assume that to probably make reducing atmospheres illegal not
that I care unless its in my back yard.