Biochemscientist
Harmless
Posts: 13
Registered: 18-8-2011
Member Is Offline
Mood: No Mood
|
|
Poor alcohol lamp performance
What are some possible causes of (and solutions to) poor alcohol lamp performance?
|
|
|
IrC
International Hazard
Posts: 2710
Registered: 7-3-2005
Location: Eureka
Member Is Offline
Mood: Discovering
|
|
Improperly trimmed wick.
"Science is the belief in the ignorance of the experts" Richard Feynman
|
|
|
Endimion17
International Hazard
Posts: 1468
Registered: 17-7-2011
Location: shores of a solar sea
Member Is Offline
Mood: speeding through time at the rate of 1 second per second
|
|
Bottle neck compressing the wick too much because the wick is too thick: cut the wick to make it narrower.
Insufficient amount of wick laying in the alcohol: get a longer wick or insert more alcohol.
Old alcohol with too much water and acetic acid in it: replacee the alcohol.
And, as IrC said - wick that hasn't been trimmed as it should. Trim the wick.
Alcohol lamps can be bitchy. There can be an explosive alcohol-air mixture above the alcohol which can ignite if the lamp is tilted or the wick holder
is elevated. It can be cool or not cool at all, depending on the case.
|
|
|
Mr. Wizard
International Hazard
Posts: 1042
Registered: 30-3-2003
Member Is Offline
Mood: No Mood
|
|
A compressed wick was my first thought. How does this happen? Somebody buys a new wick and forces it into the slot, and it is too tight. Another
problem could be the material of the wick. If it is a synthetic cloth like polyester it will melt at the end forming an impervious bead that won't
allow vapor to be emitted. Cotton cloth makes the best wicks. Another problem could be contaminated or watered down alcohol. I have used the 70%
ethanol 30% water variety in my youth, but pure denatured alcohol is better. Has the alcohol lamp been sitting with the cap off for a while? The
alcohol may have evaporated leaving water behind. Try putting some in a metal container such as aluminum foil, or the bottom of an aluminum soda can.
Light the alcohol, and see if it all burn away cleanly. If it leaves a puddle of liquid that won't burn away with a clear blue flame it's too wet with
water.
[Edited on 21-8-2011 by Mr. Wizard]
|
|
|
Melgar
Anti-Spam Agent
Posts: 2004
Registered: 23-2-2010
Location: Connecticut
Member Is Offline
Mood: Estrified
|
|
I've made lots of alcohol lamps over the years, and it's sort of a hobby of mine. One thing that has to be there is some gap that allows the air
inside and outside the lamp to equalize in pressure. If that gap isn't there, then when you light the lamp, the air inside it will heat up and
expand. This will increase the pressure inside the lamp, which will push fuel out of the wick and make a puddle around its base. The puddle will
then catch fire and the air inside the lamp will heat up even more, causing a nasty fire.
Water in the alcohol doesn't really hinder its performace much, and I've deliberately added water to the alcohol fuel in order to cool the flame.
However, when you go to light it, the alcohol will have evaporated faster than the water, so the wick will be wet with mostly water. So you have to
pinch a few drops of liquid out of the wick before you can light it. Even if you're using pure alcohol, you can have this problem, since water will
condense on the wick from the air.
Methanol has the coolest flame, then ethanol, then isopropanol. But isopropanol can produce soot whereas the other two won't.
You can give your lamp a cool green flame by mixing a little boric acid in with the alcohol.
Wicks should be either cotton or paper, so made of cellulose anyway. They should be cut significantly deeper than the lamp jar, so that as the wick
chars, you'll have enough extra to pull up a little more.
|
|
|
bobm4360
Hazard to Self
Posts: 59
Registered: 18-4-2011
Location: On a wretched little island.
Member Is Offline
Mood: No Mood
|
|
Interesting series on alcohol lamps here - http://www.modernmicroscopy.com/main.asp?article=78&page...
Regards,
Bob
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
