Propane vs. LPG

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.

| I have a gas-fired pottery kiln. In our previous house, I used to fire | it with propane (orange cylinders), as no mains gas available. In our | 'new' house we have an LPG tank in the garden for central heating etc. | Am I correct in assuming that I can run the kiln using the LPG without | changing the jets in the burners? Perhaps I should add that the | controls on the kiln include gas pressure, primary and secondary air | flow, and that firing is not an exact science, requiring frequent | monitoring of temperature rise, flame conditions etc. I don't expect | that the kiln will fire exactly as it used to, and just need to know | that changing to LPG isn't a complete no-no.

The stuff they fill your tank with is propane, even though they call it LPG.

Thank you both. I'll proceed accordingly.

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

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

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.

AJH

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

Not all of them.

Yes this is the equation for a reducing atmosphere in a kiln but the H2 is too dilute to explode, or so I thought.

My only experience with reducing atmospheres in kilns was with two old guys that worked in a "studio" next to a wood I was working, I was amazed at the colours they could get from a wood fired kiln which was in effect just a loose igloo of bricks.

AJH

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?

Oh _do_ piss off you Blairite bedwetter

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

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

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

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

The message from The Natural Philosopher contains these words:

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.