ADVICE on unsealed alcohol lamp?

Discussion on Stirling or "hot air" engines (all types)
floridajoe48
Posts: 7
Joined: Tue Feb 21, 2017 8:19 pm
Location: Florida, USA

ADVICE on unsealed alcohol lamp?

Postby floridajoe48 » Wed Feb 22, 2017 4:03 pm

SETUP: I have a stirling engine bolted onto a metal plate. I use a 33 mm tall, 5 ml glass alcohol lamp heat source because it's the only one I have small enough to fit in the space beneath the power piston. I don't like candles because of the sooty residue. I prefer a glass lamp because I can see the fuel level.
THE PROBLEM: The lamp has a metal top(wick holder) thru which the wick extends. This metal top mounts loosely into the mouth of the glass lamp. When it gets hot w/use, the alcohol vapor which leaks out around the unsealed base of the wick holder ignites in an uncontrolled conflagration. I need ideas on how to seal the metal wick holder to the mouth of the glass lamp so fumes cannot leak out around the base of the wick holder. BUT - the wick holder still needs to be easily removable so I can refill the lamp. I would prefer not to have to modify the engine to accommodate a larger lamp.
Any pertinent suggestions greatly appreciated.

Ian S C
Posts: 1984
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: ADVICE on unsealed alcohol lamp?

Postby Ian S C » Thu Feb 23, 2017 12:47 am

The important thing is to stop the heat passing down from the flame to the spirit tank. A ceramic material might be best, but stainless steel for the cap would do OK.
The burners I make for my engines use a metal container, and the wick is made from a bundle of iron wire. The container must have a vent hole.
The wick on this burner is 1/8" diameter, and it has a flame about 1/2" high, there is a vent in the filler cap.
Ian S C
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floridajoe48
Posts: 7
Joined: Tue Feb 21, 2017 8:19 pm
Location: Florida, USA

Re: ADVICE on unsealed alcohol lamp?

Postby floridajoe48 » Thu Feb 23, 2017 9:42 am

Thanks Ian S C - I will check into finding a ceramic lamp cap/wick holder - sounds like a good idea. My cap is metal (maybe "pot metal" or aluminum?),so I'm not sure a different metal cap will solve my problem. Using a metal wick also sounds like a possible solution. I could switch to a metal lamp w/o burning up my wick (I've been using a cotton wick) if it runs dry - so no need for a glass lamp.
QUESTIONS: Do metal wicks generally produce a smaller flame than cotton ones due to less/slower migration of the fuel up the wick? Mine has a 25mm(1 inch) flame, even when I stuff it down almost flat w/the wick holder.
Do you think I could use copper wire strands from an electric cord or metal from a copper/steel pot scrubber? These are easier to find where I live than iron wire.
Your balance beam engine is BEAUTIFUL! I have a store bought dual vertical oscillating beam engine, but it's nowhere near as nice as yours. Thanks, Ian.

Ian S C
Posts: 1984
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: ADVICE on unsealed alcohol lamp?

Postby Ian S C » Fri Feb 24, 2017 2:27 am

The motor was built from scrap found in the workshop.
The wire should be iron or steel, or even better stainless steel, by using these metals heat conduction is reduced, copper will conduct heat very well XX. Aluminium should not be used where there is heat, and it has similar head conductivity as copper, so even a container with a thin steel cap is good.
A single burner version of this type is even better as the flame is remote from the tank.
Ian S C
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floridajoe48
Posts: 7
Joined: Tue Feb 21, 2017 8:19 pm
Location: Florida, USA

Re: ADVICE on unsealed alcohol lamp?

Postby floridajoe48 » Fri Feb 24, 2017 10:21 am

I have located a metal spirit lamp(I think it's made of some lower grade of stainless steel or tin - it's not magnetic) short enough for my purposes, but it also has an aluminum wick holder - which is pressed/sealed into the lid of the lamp. I have ordered a fiberglass wick to use w/this lamp, since I can't see the fuel level. I do have a concern w/it. It is unvented, & when I burn it for a few minutes, it becomes fairly hot (the metal is very thin) - due to the aluminum wick holder, I assume. I'm wondering if it may pose an explosive risk, in its current configuration? Do you think placing a vent hole in the lid as far from the wick as possible might render it safer to use - or are the vented alcohol vapors likely to ignite at the vent hole? The vent hole would be located about 3/4 inch from - & about 1/8 inch below - the wick. I don't think I can remove & replace the current sealed wick holder w/a ceramic one w/o tearing up the lamp lid. Unfortunately, I lack the skills & equipment to do metal fabrication or I might attempt to construct a lamp similar to those you use. Your "remote flame" design seems inherently safer than any of the commercially available miniature spirit lamps I find.
Nice steam engine, Ian! I have acquired the parts to a home-built wobbler piston engine - but the fabrication was less than optimal (probably why it was sold) & I am currently trying to figure out how to do the necessary repairs - using only a grinder, electric drill & hand tools - if I have any hope of ever seeing it run.
If you don't mind saying - are you North island or South island? I've always wanted to visit New Zealand, but age & health considerations preclude any such travels.

Ian S C
Posts: 1984
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: ADVICE on unsealed alcohol lamp?

Postby Ian S C » Fri Feb 24, 2017 11:49 pm

Yes I live in the South Island, about 40Km by road west of Christchurch, in a town called Darfield(pop about 2000).
With any luck the wick will be loose enough to form a vent. You are unlikely to have a bomb on your hands.
The steam engine is one that I rebuilt for a friend. A few years ago we had a night class at the local High School metal shop, and made these little steam engines, I think that one was the only one that failed to steam, soon changed that. It now resides in our local museum.
Ian S C

floridajoe48
Posts: 7
Joined: Tue Feb 21, 2017 8:19 pm
Location: Florida, USA

Re: ADVICE on unsealed alcohol lamp?

Postby floridajoe48 » Sat Feb 25, 2017 9:42 am

I think you must be right. I had not considered the vapor venting thru the wick.
I also live in a small town (pop about 2300) in southern Florida. But that's about where the similarities end. It's mostly hot & sticky 9 months out of the year. This locale is as flat as yours is mountainous & the closest thing to snow we see is in the "snow cones" the children buy. We do have our share of Great Whites cruising off shore, tho - dining on seals, fish & the occasional swimmer. I don't think they really like people much. They'll usually take 1 or 2 experimental bites, then swim off in search a tastier meal. Curious, that. The people I've talked to tell me "long pig" is a flavorful, tender, juicy meat. Guess there's just no accounting for taste.
Ka kite ano, mate.


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