Why most still manucfacturer recommend running their still with 1/2 volume or over?

[Birster]

Hi,

 

I was wondering what is the reasoning/science behind the sayin that you must run still  with at least 50% of volume or more. What would happen if you run a 300 gallons capacity still with only 75 or 100 gallons of liquid in it?

Thank you in advance.

[Black Creek]

Can't speak for all of course but my still has electric heat elements and I can't imagine running it to the point that they might be exposed instead of submerged.

[Birster]

Thanks Black Creek. That one I already had it figured out, as you said it makes total sense. I'm asking this question more preciscely to steam jacketed still, if it can help narrowing down my question.

 

Thank you in advance to shed the light on this

[Huffy2k]

If your still has an angled agitator shaft (most do), you don't want to run that with any of the blades not completely submerged. 

[Skaalvenn]

Probably so you don't get a ton of mash burned onto the steam jacket.  Most of the stills I see are built with the idea in mind that scrubbing burned on mash is both pleasant and profitable for the distiller.  I understand wanting maximum jacket surface area for heat up, but I'd sacrifice 10 minutes of longer heatup time if it meant I'd spend 15 minutes less time cleaning.

Huffy2k is 100% right as well, I have pictures of a nice vendome still where the 1.25" shaft bent and send the mixing blade through the steam jacket.  You can run the agitator while draining, but you must be sure that it's turning slow enough to not self destruct when the liquid level gets low.

[Birster]

Ahhhh, now I see. It makes total sense

 

So if we were to do gin with only a gin basket in the vapor path, we would be able to fill it the way we want if we don't use the agitator and it is only clean 30-40% GNS in the still. Is my understanding correct?

 

Thanks again.

[adamOVD]

i fill halfway when i do a gin. It's only about 1/4 full by the end of the run. It works fine. I also run the agitator, but it spins slow and can run while it's empty.

[Stumpy's]

The other reason is to ensure you have enough liquid to generate adequate vapor. Example: if you are running a 20 plate column with high reflux to make vodka and your liquid level in the still becomes low, you may notice that your flow stops before you hit your "tails" cut. This is because you are not generating enough vapor to keep the base of the column pressurized enough to overcome the pressure build up from the plates and dephlegmator. You could reduce the dephlegmator at that point, but you will but up to the same issue shortly after the pressure buildup from the plates overcomes the ability of your pot to generate significant enough pressure to maintain flow again. Obviously, not as big of a deal if you are running a straight pot with no active reflux ability.