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Alcohol Flame Temperature
Name: Jack
Status: other
Age: 40s
Location: N/A
Country: N/A
Date: Wednesday, April 02, 2003
Question:
What is the temp of a blue flame of burning
Alcohol? Or how hot does alcohol burn? My name is Jack and I am a fire
safety officer in a Hospital. We just put up hand sanitizers in our
hospital. They have alcohol in them. There are questions on wether or not
these hand sanitizers are safe or not. Thank You.
Replies:
1. Flame temperatures depend upon so many factors that it is impossible to
reliably put a number on it. The temperature will depend upon the
composition of the vapor and air, the configuration of the fuel source,
the speed of the air, and so on...
2. I assume it is ethanol. If it is isopropanol the numbers will be
about the same. The ignition limits of ethanol are 3.28 -- 18.95 vol.
(alcohol/vol air)x 100. The Henry's law constant for alcohol is about 200
mol/l*atm. If Henry's law applies to the sanitizer the same as it does for
water. (You can assume this if, as I believe, the sanitizer is
predominantly water + alcohol + thickener) then a 10 gm /liter
concentration of alcohol (I just guessed about what this concentration
is.) is 2.17 moles/liter. Henry's law is: C =
Kh*P, where P is in (atm) and C is in (mol/l). So P = C/Kh = 2.2/200 =
0.01atm. Using the ideal gas law: PV=nRT 0.01 atm corresponds to:
n/V=0.01/0.082*298=4x10^4 mols/l The molar density of air (M.W. = 28) is
(n/Vair)= 1atm/0.08*298= 0.04 mol air/l.
So the Valc. / Vair ratio is 4x10^-4/ 0.04=0.01mol
alc./mol.air. The lower ignition limit for ethanol is 0.0328.
So the estimate of the sanitizer vapor pressure is somewhat lower
than the ignition limit. You might check with the manufacturer, but it
appears not to be a fire risk. Also there are regulations regarding the
ignition limits of a product. If ignition were a problem, they could not
ship the stuff by common carrier -- which I doubt.
Vince Calder
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Update: June 2012
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