Maximum Proof of Still charge with Electric Immersion heaters?

I am interested in how high of proof people have run in a boiler with electric immersion heaters? I know you can safely run 40%. Has anyone run higher safely? 50%? 60%. Again I am interested in Electric Immersion heaters. 5500W Elements. With external heat I know you can run very high % but at what point do you really risk (BOOM).


  • An interesting subject RDD. My thoughts would be below "proof" plus a safety margin (ie the point at which an alcoholic liquid ignites). Although would you also take into consideration the vapour as well?

    At the end of the run, the elements should have enough liquid covering them, to provide a "safety blanket" if one does blow or arcs across. Naturally you would have your rig properly electrically protected and earthed.

    I am by no means an expert in this field or have any background knowledge in this subject. I'm just a sparky, but I'm also interested in other members' opinions.

  • Rednose on another forum regularly runs a still charge of ~50% and I have as well.
    It made me nervous at first (simply because I was told to keep the still charge below 40% on the distilling forums, always without any supporting science) but I figure as long as the elements are covered it doesn't much matter what the ABV of the still charge is. It's not the alcohol that ignites and burns but the alcohol vapors.

  • From the safety point of view your concern is the flash point of the vapour inside the boiler - I think. From a quality point of view there is an issue that the tails will not effectively be separated if the still charge is above 40%. There are many reasons for diluting the boiler charge to lower than 30% and if you look at most of the distilleries they typically charge the boiler at 28%.

    There are some very specific applications for charging to higher proof, but in many cases the product is actually what is LEFT in the boiler. For example with Annatto. The alcohol is just a solvent and is not actually a product, but you need special boilers with indirect heating.

    Harry wrote an article on 'diluting the still charge' that is worth looking at.

  • It's been awhile Myles since I peeked at it but wasn't that for pot stilling?
    With a few runs RedDoor will probably find his comfort/ideal boiler charge setting... 35, 40, 45% etc and hopefully report back to us not only with boiler charge data but all the goodies... collection rate, cutting any heads or tails from the first run or not (since he's stripping with 11 plates!), percent of hearts collected from available alcohol and most importantly (for me) any suggestions to improve the equipment.

    We put a heavy burden on guinea pigs first adopters around here!

  • Well a boiler is a boiler, and the safety aspects apply regardless of what is in the vapour path. I am not saying that you can't distil high ABV boiler charges - clearly you can. However, the use of an immersion heater might not be the best choice. The problem for me is the high surface temperature of the element itself. It is possible to superheat the immediate vicinity of the element, before convection starts the bulk of the boiler charge circulating.

    Possibly of more relevance though to reflux operators is this fact. The higher the boiler charge, the more energy is required to separate the alcohol from the water. In the end that might be more important.

    There are also the issues of the solubility of the higher alcohols and esters, but I don't really know the details of that.

  • But the elements are at the bottom of the boiler and the event of microburst would certainly be dissipated long before reaching the surface where the flammable vapors exist?
    Like you, I find myself tossed as to safety because I've distilled 50+% without issue, yet listen to folks recite the mantra of not exceeding 40% in my head while doing it.

    Waiting for someone to chime in with first hand knowledge, not recycled folklore, for the real maximum safe boiler charge. Higher % in the boiler = faster boil up and ready to draw product, and a broader hearts cut. The very essence of double distilling.

    I'm not pushing for a 65% boiler charge (though that would not be out of the question) but rather I'm asking a fundamental distilling question that RedDoor also asks, "Why 40% boiler charge?" Just seems to me to be somebody's 'good idea' that became chiseled in stone to us home distillers without any investigation or anyone questioning it.

    Myles is a longtime home distilling heavy-hitter with lots of fans, including me - so I'm trying to weigh his comments against a higher % boiler charge.

  • I have always run a hell of a lot higher than 40% usually 60% using an elec element and never had a problem. The element is covered, there is no ignition source, there is no oxygen in the boiler. If you have a fire the vapour will burn at the exit point but it will not burn up the Liebig / off take and back into the boiler. I have had a still fire while running over a wood fire so I know this from first hand experience. A keg will not explode even if there was an ignition event in the boiler (which I can not see happening), expansion of gasses will take the path of least resistance like a barrel and you would have the pressure wave move up the column and out. As I said I really could not see that ever happening. That said a lot of people may disagree with me, I'll keep doing what I am doing but I don't advocate anyone else doing it.

  • Lloyd I have been looking back at previous discussions and some PM's with Rednose, and I just can't find a definitive answer. I am convinced that the 40% issue is related to a quality problem to do with bad tails separation, and may not be a true safety issue at all.

    All the folks I have heard of distilling high ABV charges (60% and higher) are doing so in steam jacketed boilers. Now perhaps that is just a preference for an indirectly heated boiler. I don't know.

    Potential safety problems are more likely to do with leaks of ethanol vapour (which shouldn't happen anyway), and the initial stages of warm up when the vapour in the still is still potentially explosive. It is unlikely even with flash boiling at the element surface, that you are going to get a "BOOM" situation.

    OK with a pot still there are quality reasons for keeping the still charge below 30%, but in a reflux still, I am not sure.

    If you look carefully at the safety arguments, they mainly refer to the flammability of the boiler charge, in the event of a boiler rupture. However, that doesn't really ring true. The flash point of 40% ABV is 27 degC and the flash point of 70% ABV is still 27 degC!! However, once burning, the higher proof is probably slightly more hazardous.

    I think this 40% issue might be a convention, there are a lot of experienced distillers out there that claim to run with reflux boiler charges of 40 to 45%.

    I have a gut feeling that there is some quality problem that is introduced with higher ABV boiler charges, but this might not even be with reference to neutral. It might be an issue for producing flavoured products on the column, but I can't find the original source. Even 'The Complete Distiller' makes a reference to a 40% charge but does not explain why.

    I know that I would feel more comfortable using an indirectly heated boiler, but I have never heard of a single immersion element related safety issue actually occurring.

  • Thanks Myles, that makes a lot of sense. I also feel the roots of this convention has to do with flavored spirits and running a pot still which RedDoor is not doing; he is wanting a flavorless neutral using a reflux column.

    As far as I know Rednose was the first to step forward and say that he ran higher proof than a 40% still charge. It got my attention and I timidly mimicked him. Now I think nothing of running 45-50% or so in the boiler and with 6 bubble plates a fellow has to be a really bad distiller not to pull soft and clean azeotrope.

    With 11 eight inch plates? ForGetAboutIt, can't help but happen.

  • Slight error there but it is minor. Flash point at 40% is about 26 deg C and 70% is about 21 deg C, but at still room temperature, both will probably burn if you apply an ignition source to them. If they are already hot then you can be fairly sure that both will ignite readily.

  • If he is wanting to make a neutral? That is all the more reason to dilute even further. Allowing the added water to clean the final spirit up that much more.

    Personaly I never have looked at it as a safety problem of the still charge igniting in the boiler. I think its been pointed out many times. The lack of oxygen will prevent that. But I do look at it as if that boiler was to somehow be released, spilled, or drained on the ground. Under 40% or so just makes a mess. Over 40% or so makes a potential big fire.

    Just my two nickles.

  • There is another side to this. Most of the folks that are distilling high proof charges are actually re-distilling previously made neutral with some sort of botanical. Their boiler charge is already 'clean' without heads and tails.

    This is a slightly different application to producing neutral in the first place, and it also possibly explains the preference for jacketed boilers.

    I did manage to track down 1 reference to Distillation Processes and Principles by Sydney Young, that reinforces the quality aspect.

    "The still is charged with raw spirit at about 38 percent by weight, for it is more difficult to eliminate the impurities from very concentrated alcohol."

    I think if I were producing neutral I would:

    1. strip at about 8% to 12%,
    2. do a first spirit run of the low wines diluted to 30% to 40% and
    3. a second spirit run of the high wines from run 2, re-diluted to 40% to 50%

    I also have a glycol jacketed boiler that I use for botanicals, and would not have a problem with charging that with previously made neutral at 60%.

  • Great input guys. Keep it coming. If the boiler was charged with 40% or 70% and up to running temp 85c either way a massive failure of containment would be very hazardous.

    First due to just the volume of high temp liquid of 85c. (My boiler charge is 950L) hitting the floor would be a serious scalding hazard.

    If it was 40% or 70% @ 85c either way the amount of highly volatile steam that would be rapidly released into the building I would think would cause a flash over hazard if it met an ignition source.

    My concept here was if I am running a "strip run" so to say. But driving it to 94-95% making cuts to remove heads and tails. Then taking several batches of 94-95% and watering back to say 60%. Like Lloyd says ramp time to temp would be a lot faster and most of the heads and tails are already gone so then running it thru the 11 plates again should give me a very pure final run at a good output speed.

    Of coarse I need to make sure that I keep the elements covered. So I would need to calculate the required total charge to maintain coverage over the elements. It take 90 gallons to cover my lower 4 elements so I run with a minimum residual charge of 110 g as my Safety cushion.

  • That sounds a reasonable proposition to me. With your equipment you can disregard a conventional "strip run" as you are effectively combining the first 2 stages into a single run. With 11 plates I bet you are close to neutral already, even if you take it off at 94% on the 1st run from fermented wash.

  • Correct. That is what I was thinking. Will know for sure when I receive my new 8" 11plate in a few weeks from Lloyd.

  • Another thing to think about. If you charge the boiler with a higher ABV. The boiling point will be lower. So it would take less heat input to run the still. If you have a good controller for the element. This would be no problem. But if you had no control over it it bad control. It could be a pita.

  • Even with a 60% boiler charge with a run for neutral I have seen no loss of quality, you get a very good clean product from what I have seen.

  • @spud1700 said: Even with a 60% boiler charge with a run for neutral I have seen no loss of quality, you get a very good clean product from what I have seen.

    Spud do you run internal immersion elements? Or externally fired?

  • Immersion Elements, 2400 watt element in a 50 ltr keg. Running a reflux still on top of it, LM/VM befor but now a LM/VM on top of a meter of three inch over two plates.

  • Interesting Spud, Do you do a strip run then 1 spirit run or do you do 2 spirit runs? Any cuts on the strip run?

  • Hate to (and embarresed) to admit it. I poured low wines onto a hot element.

    Boom, lost my eyebrows, burned lips are painfull.

  • I strip using the pot still most of the time, keep the higher ABV stuff see separate from the low ABV stuff from the stripping run and use the higher ABV stuff so I suppose you could say there is bugger all tails in it. Also add stuff from the last spirit run (the end of it if there is any chance of any tails contamination) anything I may not have been happy with previously,that may be 95%, anything that I do not like and have laying around such as infused fruit neutral that I am not keen on. I never dilute a charge down to 40% I have found if you have a charge that is a lot higher it saves a lot of time and the product is still as clean as. When I do separate runs with a lot of tails the product is still very clean but the remaining boiler charge is revolting, it really stinks. I have a lot of people say they have read don't go over 40%, I tell them I always run well over 40% and never had an issue but it is their choice how they want to run and if they are not comfortable over 40% then don't run over 40%.

  • @Law_Of_Ohms said: Hate to (and embarresed) to admit it. I poured low wines onto a hot element.

    Boom, lost my eyebrows, burned lips are painfull.

    That explains your new avatar =))

  • Like throwing petrol on a fire :)

  • edited June 2013

    @Law_Of_Ohms said: Hate to (and embarresed) to admit it. I poured low wines onto a hot element.

    Boom, lost my eyebrows, burned lips are painfull.

    No lost eyebrows,but burned lips siphoning hot back(ONCE),sucks wind big time! =;

    It is what you make it!

  • @Law_Of_Ohms said: Hate to (and embarresed) to admit it. I poured low wines onto a hot element.

    Boom, lost my eyebrows, burned lips are painfull.

    Ouch. Yeah that was probably not the best decision to have made.... I think we have all made some bad choices at some point.

    I choked my column once and had to open then emergency vent valve to dump pressure. Unfortunately my arm was over the top of the vent port when I let her loose. Pressurized steam blasting on the soft inside of your arm does not feel good and leaves a nasty burn fast...

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