Replacing Dual Valve VM Head

edited March 2016 in General

I am trying to replace my current VM head which is a standard horizontal tee piece design with a ball valve on either side. I want to retain the horizontal tee configuration but replace the whole head with a single bottom entry 3 way ball valve. The only problem I can see would be needing to have the valve ball bored at 125 deg ( not the standard 90 or 180 deg) I'm thinking that by having the ball bored at 125 deg one opposing horizontal port will close proportionally to the opening of the other.

Has anyone ever tried this?


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  • edited March 2016

    Are you using this style?
    Any particular reason why you wish to change it?


    zet still.jpg
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  • Yes that style, it works well but I find I don't use a lot of the available adjustment on the gate valves, and thought if it was not to difficult to custom drill a valve ball I might be able to achieve the same with a single valve and save a little height

  • I think the best solution is a bellcrank/leverage one.. picture two ball valves with the handles towards you, fabricate both handles so that the valve orifices are pointing 45 degrees up to the center than the handles are pointing straight up. make the handles long and have a means of attaching a tie-rod at any place along the handle (bunch of holes, channnel, etc".. you move the lever one way it opens one valve fully and closes the other fully.. by moving the tie-rod up and down on one or both sides, you can get all sorts of ratios...

  • edited March 2016

    Honestly can't see how this will work with a single 3 way valve, no matter how you bore it.


    Now if you had 2 ball valves on a common shaft, or two coupled valves as suggested above then yes. Won't do anything for the height issue unless you mount the valves horizontally - and you can do that with the existing valves.

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  • If you're like me you've found you only use 2 positions:

    1. Shut for full reflux
    2. 10% open for a spirit run

    As you've found, the gate valve has far more flexibility than you're ever going to need if you run a consist power and a consistent feed.

    I suspect you could replace the current control system with a single ball valve for full reflux that then reduces to the equivalent of my/your 10% open for your 95+% abv neutral output.

    What I don't understand is how any of this manages to reduce your overall height?



  • edited March 2016

    Wouldn't this application require a (very rare) linear diverting valve? Which is exactly what the two globe valves are approximating.


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  • edited March 2016

    If you want to get trick - why don't you use two solenoids - one normally open, one normally closed - and wire them to a variable duty cycle control. You would be able to retrofit without too many plumbing changes.

  • Or a single ball valve on the pc and an orifice on the rc

  • If you point the pc arm down you should be able to go from 0% to 100% if the tubes a large enough. The 50:50 split for an equal tee is a complete myth. I get pot still mode with a 2" tee and a 2" butterfly valve on the pc arm wide open. Nothing makes it to the rc at all due to the vapour density.
    It looks like a cool head but there's simpler ways.

  • It is a cool head design one of Harry's i do believe... Patchworkdoll's was the first one i saw a photo of... Minime had a version of this head which was his go to unit... Myles may have been in on some early work on it as well not sure...

    Why change it ... its a proven design at this point... home distiller size...

  • edited March 2016

    This is a proportional splitting version. I never bothered to implement it because on my packed column I only use it to make a single product. Neutral.

    So for me it is unnecessary. However, if you are making flavoured product on the packed column then the ability to change the reflux ratio infinitely between 0% and 100% may be of value.

    My interpretation of a VM/LM head works fine for what I use it for.


    I disagree about the 50:50 myth though. I still get output from my reflux condenser even with the valve wide open.

    VM Head.jpg
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  • That's another cool looking one.

    @Myles said: I disagree about the 50:50 myth though. I still get output from my reflux condenser even with the valve wide open.

    Have you bothered to measure the amount? What I said is still correct.
    Your RC is at the same level as the tee (not above it) so the vapour doesn't have to flow uphill like a normal VM.
    The point is vapour density has a very large effect on the split. A lot more than the size of the tee/take off alone.
    Small diameter lines with high vapour speeds can overcome this a bit but if you bother to check what the RR actually is you'll quickly see what I'm on about.
    I do actually have a pretty cool RR readout for VMs like this. It only needs three temp probes but gives a repeatable readout of the exact reflux ratio eg "88%", regardless of boiler power or feed water temp etc.

    Do you find that having the valve on the vertical like that collects liquid when at 100% RR?

  • edited March 2016

    Not much. I insulate the whole head, except the condenser, and even the valve gets quite hot. My own with a coil condenser instead of the tube and shell version, is shown below.

    Sometimes there is a few drops but it is minimal. With this style and the reduction in diameter, the vapour speed should be increased, such that it is going to split anyway once it hits that physical obstruction.

    I am not sure the density issue is as important as it is in the conventional version when the vapour needs to travel vertically above the VM port to get into the reflux condenser.

    my own personal one.


    Just for interest I found this one of the best configurations, with a packed section above the VM port, but the extra height made it impractical for my own use.


    No pooling at all with a slight up slope on the VM branch.

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  • @Myles said: ...with a packed section above the VM port,

    Heads trap?

  • Absolutely. I removed most of the heads (as vapour through the RC air vent to a separate small condenser, CM mode) and then found that the last bit would be retained in the upper column so that I didn't need to get every last trace out.

    It is good but takes a lot of height.

  • Thanks guys, some of those things I never even thought of. A work mate confirmed he has been successfully using for some time a standard 3 way L port valve mounted vertically and with the metal removed between the ports of the ball (a home made sectioned ball) Something I might have to try if I can find a valve the is actually servicable

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