Ethanol Flash Point

[Andy Capp]

This is an interesting subject. We always dilute to 40% but for what purpose? The flash point of 60% ethanol is 22C while 40% ethanol is 26C. Once heated up in the boiler, it doesn't really matter what the % is. Even a 10% solution can be ignited at 49C. While i'm not arguing against diluting our low wines before distilling, i question whether it will make us any safer once the solution is heated past its flash point.

[Dnderhead]

as you probably know o2 and fuel makes a bomb,so if you start with a wash below 50% the air will be purged from the boiler before any ignition.

[Andy Capp]

I agree with the part about purging oxygen making the still safer and would like to discuss that further. But the point i was trying to make is that the solution becomes flammable once heated in the boiler.In warmer climates, the solution may already be flammable before entering the boiler. If a leak was to occur, the liquid could be ignited causing a fair bit of mayhem. I have read posts by members that are giving advise to dilute to 40% because this makes the solution non-flammable and this is not true. I wonder how many members have been given this false sense of security while operating with propane burners?

[rad14701]

40% shouldn't be flammable but we all know it can be... You don't have to go much lower to have the boiler charge not be flammable... We're talking the liquid component, not the volatile vapor in the head space...

[Doogie]

Don't think the first stuff filling up the boiler with vapor would be ethanol though ...

[Andy Capp]

As a test i put a shot of my 38% vodka in an ice cream scoop and heated it underneath with a lighter. Then i put the lighter to the vodka and hey presto...blue flame. It doesn't burn as well as higher ethanol content solutions do but it still burnt. Therefore it is flammable.

[Kal]

I think the flash point of ethanol is irrelevant. The vapours floating around in the still are much higher percent alcohol, and much higher temperature than the flash point. The safety aspect of diluting to below 40% is due to the point at which the liquid will sustain a fire, so if the boiler spills you don't have a massive amount of liquid suddenly on fire.

The 38% in the ice-cream scoop is interesting. Perhaps a weaker dilution should be recommended? Personally I water my spirit runs down to about 30% anyway to play it safe.

[Andy Capp]

The flash point is very relevant. While a 40% ethanol/water mix is safe at room temperature, it becomes flammable once heated to its flash point at 26c. This means that a low wines charge becomes flammable soon after the boiler is switched on. If a boiler did spill, the liquid could catch fire if something nearby was to ignite it. While it won't burn with the energy of jet fuel, it could carry a fire to areas of your distilling room that may contain other flammable hazards.
All i'm sayin is we need to be more carefull and give ethanol mixtures more respect than what i believe is being given at the moment.

[Richard7]

I completely get what you are saying Andy Capp,

I found this chart on wiki,



Flammability

An ethanol-water solution that contains 40% ABV (alcohol by volume) will catch fire if heated to about 26 °C (79 °F) and if an ignition source is applied to it. This is called its flash point.[34] The flash point of pure ethanol is 16.60 °C (61.88 °F), less than average room temperature.[35]

The flash points of ethanol concentrations from 10% ABV to 96% ABV are shown below:[36]

10% — 49 °C (120 °F)
12.5% — about 52 °C (126 °F)
20% — 36 °C (97 °F)
30% — 29 °C (84 °F)
40% — 26 °C (79 °F)
50% — 24 °C (75 °F)
60% — 22 °C (72 °F)
70% — 21 °C (70 °F)
80% — 20 °C (68 °F)
90% — 17 °C (63 °F)
96% — 17 °C (63 °F)

Alcoholic beverages that have a low concentration of ethanol will burn if sufficiently heated and an ignition source (such as an electric spark or a match) is applied to them. For example, the flash point of ordinary wine containing 12.5% ethanol is about 52 °C (126 °F).[37]


So from what I can tell if you have a wash or mash (not even diluted low wines) that is 10% it will be flammable @ 49 C or 120 F.

[Richard7]

I just tried your scoop test with a spoon. 20% burned just fine 10% burned just fine.........
Thanks, now I have something else to worry about!

No really thanks, it is best to be aware of these things

No alcohol was harmed in my test other than what got burned. I am drinking the remaining 10% stuff out of the test cylinder.

[rad14701]

It is not a matter of whether it will burn when heated, it is more important whether it will burn once it comes into contact with cooler surfaces in the ambient environment... How fast it cools determines the extent of collateral damage... There is no guarantee against damage in the event of a catastrophic incident...