Operational Safety Guidelines

The next greatest risk to distillers is that of fire and subsequent explosion

You will be producing a liquid, which is on a par with gasoline with flammability, yet doing so around heating elements (or even gas flames).

The primary danger is that of explosion or burning of the alcohol. Most distillers immediately recognize the potential explosion or fire dangers of distilling a petroleum fraction to produce gasoline. Alcohol and gasoline fuels share these common risks-a primary reason they are such excellent fuel sources for spark ignition engines, which actually use a controlled explosion to produce power the table below lists some characteristics of both fuels.

Alcohol vapor is explosive when mixed with air in amounts ranging from 3-19 percent by volume, at room temperature and atmospheric pressure. Gasoline vapor is explosive when mixed with air in the range of from 1.4-7.6 percent by volume for the same temperature and pressure conditions. Both alcohol and gasoline vapors are heavier than air, which may add to their accumulation in enclosed areas or in low-lying ground depressions around or down stream from the vapor source.

It is of critical importance that we should all be aware of the dangers involved in distilling alcohol.


Characteristics of Ethanol and Gasoline

In order to illustrate the risk of working with Ethanol, I have made a comparision with a substance of which we all know how dangerous it is.

Ethanol Gasoline
Ignition temperature 689 F 536 F
Vapor flammability limit 3.3-19 1.4-7 6 (% by volume)
Specific gravity 0.8 0.8 (Water equals 1)
Vapor density 1.8 3-4 (Air equals 1)
Boiling point 172 F 100-400 F
Flash point 55 F -44 F

Fire!

1978, Fire at a distillery, Echt, The Netherlands

Safety guidelines

In general: 
Check your still with water-only the first time you use it, to make sure your condenser is up to the job. You don't want vapor coming out of the collection tube.
NEVER, NEVER, NEVER leave a still unattended. 

Murphy's Law says that if anything can go wrong, it will. Stillcooker's Law says it will ALWAYS happen the exact moment when you aren't paying attention. 
Be sober - its not a time to be making drunken mistakes. Don't smoke - you don't want ignition sources around a liquid as flammable as gasoline fire.

 

Read the guidelines BEFORE you fire up your still!!

With respect to your still, keep in mind the following:

Boiler - electric fired: 
Still pots or boilers that are fired with electric elements should have a sight-level tube incorporated into them.
This will eliminate the potentially explosive situation of not covering the element(s) properly with wash. Heating an uncovered element will case it to get   red-hot. Metal casing, hot element/s ethanol fumes and unpurged air = B O M B !!! 

The cost is cheap, and can be as simple as a couple of elbow joints and a joining clear plastic tube with a red plastic hollow bead in it as a float indicator. This serves double duty as it allows you to monitor your remaining wash level at all times thus  you'll have a good idea when you're coming to the end of your run. 

Boiler: Gas fired (Propane tank of natural gas): 
NEVER have your propane cylinder near the actual burner, and NEVER between the burner and your product collection  point. Even a small 9kg cylinder makes a spectacular explosion when heated to ignition. Always make sure the shut-off valve is located where you can quickly reach it, without risk of yourself being burned. 

When using propane ALWAYS have the product collection point BELOW the level of the burner. Ethanol fumes are heavier than air (1.6 : 1) and any stray fumes will creep at the lowest level (floor). If your flame source is well above this level, then the possibility of a chance vapour ignition is limited.

For the same reason, ALWAYS put an extractor fan at floor level to remove any fumes. This fan should be placed in a doorway to the outside. The line-of-sight setup is...open door---fan---collection point---burner. NEVER draw fumes past a burner point,  or upwards from the floor to a higher window, for obvious reasons. The object of the game is to always keep any possible  fumes and any flame source APART from each other. 

Condensor: 
Not everyone is cut out for appliance repair and maintenance. Therefore, it is imperative to check and re-check all fittings, coolant hose connections etc. in your rig before you fire it up. Check it each and every time. If your coolant system isn't operating properly, there's a risk of un-condensed ethanol fumes being vented to the surroundings. These can render you unconscious, or find a flame or other ignition source.

Check any condensers or other open tubes for blockages such as insects (wasps, mud-nests), or kids small toys shoved up  the openings. Pressure in a still is ABSOLUTELY A NO-GO! 

Your stillroom: 
Don't distill in a closed room. Try and keep some through-draught (e.g. both a window and door open).
Keep a fire extinguisher with you (and on your side of whatever is going to catch fire).

Product Collection: 
NEVER USE wide-mouthed collection vessels. There's too much risk of ethanol fumes straying into the surrounding area. Use narrow-neck containers, with the collection outlet actually inside the neck, and a wad of cotton wool to loosely plug the  neck.
Collect the alcohol securely - don't put yourself in a position where its easy to knock over the collection vessel etc, or bump the tube out of it. This means having enough space to work in, well lit, tidy.  

Always use a sticky label & mark every bottle with what's in it and what strength it is. Better yet to habitually use a different set of bottles for your drinking strength stuff to your high-test stuff. It's too easy to forget what's in a particular bottle. This can lead to accidental overdosing, either by you or maybe even by an inquisitive kid thinking it's water.

Last but not least:
You need a license to operate a still in most states. I am fully licensed and so should you! If you want to know your position and how you can obtain the required permits, I strongly suggest that you check information on the site of the USA Alcohol and Tabacco Tax & TradeBureau. The link to section regarding distilled spirits is: http://www.ttb.gov/spirits/index.shtml

See also: "Home distillation of alcohol" by Tony Ackland (www.homedistiller.org)