Testing Electrical Resistance of Distillate

jmc91199 · Post by **jmc91199** » Thu Sep 21, 2006 10:17 am

Here is one for you physics and chemistry types. I've seen some Parrot Spouts that are used to measure abv as a continuous flow from the still. It seems like it would be a little slow to respond to changes in abv from the head, especially when you operate a small still (4gal boiler) like me. Is there another set of properties that we can test like electrical resistance? The theory is that if the relationship of resistance to abv is linear then we easily calc abv from a resistance value. If I understand resistance testing it requires passing a really small amount of current through the distillate. Electricity and alcohol are not good bed fellows. Maybe resistance is a bad choice but what would be a good choice. What other properties or testing methods could we use to measure abv. What do you think?

Rocky_Creek · Post by **Rocky_Creek** » Thu Sep 21, 2006 11:47 am

I rarely test until calculating what I need to get barrel or drinking proof.

rangaz · Post by **rangaz** » Thu Sep 21, 2006 9:42 pm

cant recommend resistance testing. it would require very accurate equipment as there are huge possible errors from reading the tiny currents and that doesnt come cheap. also, readings would probably change considerably with temp etc.

jmc91199 · Post by **jmc91199** » Fri Sep 22, 2006 5:10 am

Thanks for the response guys. To be sure this is more of an intellectual exercise than a quest for a solution. I thought it would be fun to kick around some crazy ideas.

I think you are right about resistance being a bad option however i still wonder if there is still another physical property that we may test to achieve the same result. equipment, time, and effort not withstanding.

Watershed · Post by **Watershed** » Fri Sep 22, 2006 6:04 am

Conductivity meters aren't that expensive - fifty quid will get you a sensitive one. Whether or not it would work I don't know - it depends on the chemistry of the distillate. Pure water does not appreciably conduct electricity, the stuff we use in the lab has a resistance of 18 megaohms, a pure 50:50 mix of ethanol and water should come out about the same.

I suspect in practise that the conductivity will so affected by fruit acids and esters that come over plus trace metals from the coil that it just wouldn't be reliable unless you were doing exactly the same wash over and over again.

There used to be alcometers for home brewing that relied of surface tension in a capillary - the fluid was drawn along the capillary to a distance proportional to the alcohol content. Buggered if I know how reliable they were, since I haven't seen one for years, they were probably useless.

possum · Post by **possum** » Fri Sep 22, 2006 6:53 am

18mega ohms-cm=Resistivity of compleatly distilled,de-ionized h2o
Any trace ions in the water( like ions from the boiler walls) will drastically change the Resistivity/restance of the sample.
Sodium and potasium ions would really screw with the readings for this method of analysis.

Post by **stillvodka** » Sat Sep 23, 2006 9:36 am

What in the hell is this all about

am i on the right forum

Rebel_Yell · Post by **Rebel_Yell** » Sat Sep 23, 2006 12:52 pm

"stillvodka"
What in the hell is this all about am i on the right forum

LOL How about a discussion on a better way to measure the ABV percent in real time so that you can better tell when the tails are distilling out....

The electrical resistance varies too widely due to trace elements to be a predictiable indicater.

Tis a great discussion about what ifs.

rectifier · Post by **rectifier** » Sat Sep 23, 2006 7:26 pm

I agree that ABV probably can't be measured this way easily.

However - if the results are getting "screwed up" by acids - this would be perfect to detect congeners!

It doesn't matter if the results are different every time as long as the general trends remain the same. Say, conductivity starts high and dropping. When it levels out, the heads are gone. When it rises again, that's the tails. Better than knowing the ABV, I'd think... someone should give it a try. Automatic cutting, while no fun with whiskeys and rums, would allow pretty easy neutral spirit runs...

Hackers · Post by **Hackers** » Sun Sep 24, 2006 1:42 am

I like you're thinking. Just for the hell of it I might build a circuit or two, got a few ideas also how about checking for the acidity of the wash, could be cool doing electronic litmis tests heee heee haaa

Will let you know what I find out

rangaz · Post by **rangaz** » Sun Sep 24, 2006 4:13 am

cant remember how much they are, but you can buy electronic pH meters. they only allow H ions through a membrane and then measure the electrical conductivity, working out how much acid is in solution. If measuring with ordinary ohmeters (pretty sure thats wat theyre called), you measure all the other ions as well, giving wrong results. These could be picked up from anywhere in the still. If someone could find a pH meter it could work well...
forseeable problems, dissolved gases, however little, might ionise and change pH considerably as it will be close to 7.[/quote]

Post by **Uncle Jesse** » Sun Sep 24, 2006 8:22 am

long ago Fourway or someone posted an excellent message with ways moonshiners can determine proof. all the clues were rule-of-thumb and generally visual.

maybe someone can find that post

Rebel_Yell · Post by **Rebel_Yell** » Sun Sep 24, 2006 9:13 am

http://homedistiller.org/forum/viewtopi ... light=feel

http://homedistiller.org/forum/viewtopi ... light=feel

I found this through a search of the forum.

hornedrhodent · Post by **hornedrhodent** » Mon Sep 25, 2006 1:52 am

That will be a challenge to the electronics boys - to use electrickery to measure 'feel'.

rectifier · Post by **rectifier** » Mon Sep 25, 2006 4:46 pm

You can measure *anything* with electrickery.

Next rum I make I will fire up the datalogger and get a conductivity profile for fun, and post it up.

Don't let that deter any of you from doing it first though, because it may be awhile. Distilling has fallen a bit by the wayside to brewing, since I just got a CO2 setup and kegerator...