any experience with stove glass in a rocket?

[hodaka]

I'm new to this forum, and saw an earlier post that touched on the possible use of some glass (designed for wood or coal stoves) in a rocket stove. The idea, of course, is to be able to see the burning fire, strictly for the visual enjoyment of that. I've no doubt any glass detracts from heating efficiency, at least a little. From the web, it looks like the type of glass designed to stand up to heat is called "Pyroceram" and/or "Neoceram".

I'm wondering if anyone has any experience with such glass in a rocket stove, with one piece of glass (say a circular piece about 12" in diameter) placed in such a way as to be able to see the burning fire. It seems to me that some of the firebrick (say along one side of the burn chamber) would necessarily be removed, and of course there would be the risk of breaking the glass sooner or later. And there is the question of whether the glass would need to be removed/cleaned from time to time. Nonetheless, I like the idea of being able to see the fire. Any thoughts/experiences? Thanks.

[Donkey]

Welcome to the forum..

I've often thought of the glass, talked about it, etc.. So far I'm all talk.
I'd like to see someone do it.

My understanding is that heat shock can bust even the hearty-est glass, and that when glass is included in a stove or fireplace it is usually placed so that air flowing into the stove keeps it cool(er).. This is gonna be difficult down in the burn tunnel, where you want it to be as hot as possible.
On the other hand, it could very well be that an evenly heated piece of glass may not break.. And it's possible that cheaper glass is used (as you see it) in the usual stove/fireplace setting. Perhaps something better could be found.

I guess you will just have to try it. Before you go buying something expensive that might break right away, see if you can find a piece off of an old stove. Look in your local scrap yard, transfer station or wherever such things can be found..

[peterberg]

Normal fire proof borosilicate glass is found as "Pyrex". Can withstand 550 F, if I'll recall correctly. Oven ware is made of that type.
For a piece of transparent ceramic there are only two choices: Neoceram, by Asahi Glass I believe, and Robax, by Schott in Germany. Both can withstand 1400 F, if used in a small piece it wouldn't cool the burn tunnel too much down.

[johnjmw]

I would think it would be safest to use it int the bottom of the feed tube where the wood is actually burning but the heat is being pulled away. Yet using it along the burn tunnel would give of far more light and would make watching for more interesting. I'd worry about possibly uneven heating when placed along the tunnel.

Just jumped online to check a cost on Neoceram. An 8"x10" 3/8" thick piece to try with would only cost $25. 8x10 may be small but not bad for a test.
John

[johnf]

I was wondering about this in a "rocket" lantern.
I'd thought that the burn region would be metal or ceramic and enclosed in insulation, but higher up when combustion is still ongoing, have a clear chimney. Stipulated that relatively slow, even pre-heating would be required.

Thought about a railroad lantern chimney, but I think they're at best just tempered glass -and would the bubble-shape in the middle and the narrower top end have any drastic effect if you designed for flow through the smallest cross-sectional area encountered?

There are some hobbyist glass blowers around (smoking-pipes), and I was toying with asking one for a straight pyrex tube.
Could an updraft gassification burner have a burn chamber/chimney as small as 2", fed by a single (maximum) 1/2" diameter stick (Bottom-burning self-feed would be nice)
A pyrex tube from a hobbyist glass blower wouldn't be too expensive -their pipes can be expensive, but I don't want any fancy bubbles or colored streaks.

Dean Still, June 2003
www.bioenergylists.org/stovesdoc/Still/lantern/lantern.html


(first post! thanks all.)
John Frazer
Boulder, Co