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Puffing out of the condenser


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Hi all,

My first post past introduction - so be kind to the newbie. :)

When performing a run, I often hear a puffing sound coming out of the condenser, sometimes while having dripping product, sometime in place of it. I don't see much about this in literature or online posts. Is this normal? The condenser water is cold (around 60F). Let me know what other info you need to help provide insight. I do find it occurs more at the end of hearts and through the rest of the run until I shut my heat off.


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Commonly called 'huffing' in the hobby community, typically seen with single tube in shell Leibig condensers. Sometimes due to the geometry of the condenser, where the vapor path is too narrow for the vapor speed, and especially if the coolant is very cold, or the angle not allowing fast enough drain off. Creates a kind of resonance where the vapor rapidly condenses, the condenser sucks air in to make up for the volume, the air is purged and as vapor refills the condenser it rapidly crashes again. In mild situations it'll show up as a slight wavering in the take off speed. Usually poor condenser design but sometimes due to blowing through very cold coolant at too high a flow rate.

If it is actually uncondensed vapor, do not run this equipment until you get the problem fixed or adjust your operating method to avoid it.

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My still used to do that.

Fixed it by putting the outlet under the condensate to create a vapor break so it is difficult to draw cold air back into still.

A parrot will do same thing.

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ok - I lit a lighter just inside my collection container to ensure it's not flammable vapor - so I think I'm safe there. (just kidding - that is stupidity at it's finest) :)

I'll either just deal with the huffing or insert something in the condenser tube to limit the effect. I even notice during spirit runs that the whole condenser has a certain resonation that causes the whole thing to gently vibrate. I'm guessing (at least in part) it's due to huffing resonation exacerbated by the stack of bricks the condenser is on.

Thanks all!

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