Grease, now it makes more sense. 

Chris.

Wysłane z iPhone'a

Dnia Mar 26, 2014 o godz. 19:08 David Beierl <dbeierl@ATTGLOBAL.NET> napisał(a):

> At 05:49 PM 3/26/2014, Larry Alofs wrote:
>> What intrigues me about the original question is what actually
>> happens when you heat a mixture (say 50-50) of water and ethylene
>> glycol to its boiling point.  Does the ethylene glycol become more
>> concentrated or do they vaporize together as happens when we use
>> acetone for examle to dry lab glassware.
> 
> Me too.  I haven't found anything conclusive with a mild search.  A
> few data point:
> 
> If you take a 70:30 glycerine:water mixture in a sprinkler system and
> spray it into a domestic grease fire in Truckee, California, there
> will be a big explosion that kills your wife and burns you severely,
> blows window glass 85 feet, and knocks the casings of pre-cased
> interior doors apart.  This seems to be the event that caught the
> NFPA's attention in 2009, though similar things had happened before.
> 
> At least one 50:50 premix MSDS lists it as NFPA 704 fire 1, health 2,
> reactivity 1; same as pure ethylene glycol.  It shows flash point as
> N/A because >20% water, but autoignition temp 748F (quoted as pure glycol).
> 
> Ethylene glycol just makes it into NFPA 704 fire 1, as its flash
> point (closed-cup method) is about 238F against a threshold of 200F for fire 2.
> 
> Autoignition point is listed variously at 748F or 770F.
> 
> Boiling point 387F.
> 
> Heat of vaporization 369 BTU/lb vs 970 BTU/lb for water.
> 
> Comparison: autoignition point of gasoline varies by composition,
> range of roughly 475-535F.  Diesel about 410F.  Propane about
> 880F.  Paper about 425-475F.  Triethylborane -4F. <-- watch out for that stuff!
> 
> I suspect that a lot depends on the particular conditions obtaining
> at the time.
> 
> Yrs,
> d