Take-off valve positioning...

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zed255
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Take-off valve positioning...

Post by zed255 » Sun Feb 19, 2017 12:13 pm

I'm working on a Nixon-Stone design and have built a 1/4" inside 1/2" Liebig type cooler for product, about 12" long, that will be vertical. I can choose to position the product take-off valve either above the Liebig or below it. I can see pros and cons of both positions but have no experience to help me decide where to put it. Can anyone offer experienced views on what the best position is?
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der wo
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Re: Take-off valve positioning...

Post by der wo » Sun Feb 19, 2017 12:22 pm

Above the liebig.
I see only pros with above and only cons with below.
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Re: Take-off valve positioning...

Post by zed255 » Sun Feb 19, 2017 12:37 pm

der wo,

Could you elaborate a little?

One potential advantage putting the valve below is having the weight of some product above the valve will create a little pressure that might make adjusting the valve a little easier or more consistent. I'm only making a speculation here.
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Re: Take-off valve positioning...

Post by der wo » Sun Feb 19, 2017 12:44 pm

You want the distillate pool as small as possible. Less smearing and faster reaction. If you have the valve below the liebig, the liebig is added to the pool. For example at the beginning of the run, the first distillate goes down the liebig and never gets redistilled. So you don't get the superior fores concentration a LM is famous for.
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Re: Take-off valve positioning...

Post by rad14701 » Sun Feb 19, 2017 12:45 pm

My valve is below the product condenser and I've had zero problems with smearing... The 1/4" holds so little volume that it simply isn't an issue... The benefit is that the spirits come out at almost the perfect temperature and doesn't require temperature correction for %ABV readings... Without the valve at the bottom the spirits really didn't have enough dwell time to cool adequately... Having run both ways, the bottom orientation wins out from my personal experience...

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Re: Take-off valve positioning...

Post by der wo » Sun Feb 19, 2017 12:58 pm

I don't measure the abv during the run, my thermometer tells me the abv. So I don't care about the temperature of the distillate.

But it's interesting. Never heard this opinion. I just right now look at your still pics. The valve is above the product cooler. It's always interesting when members change details.
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Re: Take-off valve positioning...

Post by rad14701 » Sun Feb 19, 2017 2:05 pm

der wo wrote:I don't measure the abv during the run, my thermometer tells me the abv. So I don't care about the temperature of the distillate.

But it's interesting. Never heard this opinion. I just right now look at your still pics. The valve is above the product cooler. It's always interesting when members change details.
In older pics the valve is above the product liebig but now it is below and has been for several years... It can be placed at either end but I always assemble the still with the valve at the bottom for better cooling because with the valve located at the top the spirits came out steaming...

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Re: Take-off valve positioning...

Post by zed255 » Mon Feb 20, 2017 9:40 am

OK, as per what appears to be usual, we have two opinions and no clear answer.

I had originally thought of putting a large ball valve at the top and the needle valve at the bottom, but that was before deciding on a very narrow Liebig-style cooler. Initially I was going to put 1/2" through either 3/4" or 1", but thought the larger volume needed to fill the product cooler would risk throwing the system off equilibrium when the ball valve was initially thrown open. Maybe that is an issue and maybe not; I have no experience at to whether this would be an issue or not with a higher volume Liebig as a product cooler. Any thoughts on using two different valves? The ball would be an on-off affair at the top with the needle regulating take-off at the bottom.

I'm inclined to place a single needle valve at the bottom of the product cooler for a few reasons:

1) I expect greater 'dwell' time for the product distillate inside the cooler and therefore very cool or possibly even output approaching the inlet water temperature (quite cold in my region).
2) The column height will create some small amount of pressure at the bottom which should make valve setting more repeatable.
3) The low volume arrangement using 1/4" OD inside tube shouldn't interfere with making cuts (smearing is the term, IIRC).
4) Makes for simpler construction with less non-copper / stainless components (since most potable water valves are brass and teflon).

Other ideas / experiences welcomed.
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Re: Take-off valve positioning...

Post by StillerBoy » Mon Feb 20, 2017 9:55 am

zed255 wrote:Initially I was going to put 1/2" through either 3/4" or 1", but thought the larger volume needed to fill the product cooler would risk throwing the system off equilibrium when the ball valve was initially thrown open.
Another option would be to 3/8" tubing inside 1/2" about 12" of cooling area with 14 gauge solid wire wrapped around the 3/8 tube with the valve at the bottom.. equilibrium will always be thrown off to some extent on initial opening of the valve, how much is dependant on how fast and how much.. done slowly it is very minimal..

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