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Thread: Gravity Releaser?

  1. #1
    Guest

    Default Gravity Releaser?

    OK guys, bear with me here. We've played with pipeline and vacuums for a few years, but never used a releaser. We have Zero brand dairy bulk tanks for our sap tanks in the woods; these bulk tanks were designed to hold a vacuum. We have a vacuum fitting in one hole on top and a manifold for the mainlines in another hole on top. We got a good deal (free) on a 900 gallon SS cheese vat that we want to use for a sap tank, but now we need a releaser device. Cheap is good, free is better. Our evaporator engineer has tested a gravity-based releaser... no moving parts. I'm hoping someone can apply some engineering or experience to his idea, and maybe improve upon it...

    Imagine a 3" PVC pipe, about 20'-22' long, mounted vertically inside the bottom half of a 50 gallon drum, with the bottom of the pipe supported 2-3" off the bottom of the drum. The drum would be along the outside of the vat, with an outlet pipe about 2" from the top of the drum running into the vat. The vacuum line from the pump would be connected to the very top of the 3" PVC pipe, with the top totally sealed. 3/4" mainline fittings would be 3-5' down from the top. The extra 3-5' between the sap inlets and vacuum fitting are the safety buffer to help prevent sap from getting into the pump. You run your 3/4" mainlines up to the fittings. He suggests a pinhole at the bottom of the mainlines as they begin to curve upwards in order to allow a small amount of air in to carry up the sap. The way this works is that you start out with the drum full of sap in order to form a seal at the bottom of the PVC pipe. You start the vaccuum and it will draw up some of the sap from the drum and create a vaccuum in the mainlines. Sap will be drawn up the mainlines and into the PVC pipe, increasing the column of sap in the pipe. Eventually, the weight of the growing sap column can no longer be maintained by the vacuum, and gravity will cause some of the sap to be released from the PVC pipe via the 2-3" gap at the bottom. Once the sap level gets to the drain pipe in the drum, it will begin draining into the cheese vat.

    My question is not so much a matter of *if* this works, since he already has one of these working at another producer's operation. My question is whether anyone has heard of or seen something like this, and if there is a better design that does not require the high vertical lift. Naturally, a wider PVC pipe will reduce the height required, since the operation is dependent upon the weight of the column of sap. He started with 3" PVC since there apparently is a direct relationship between 1' of 3" PVC = 1" of vacuum.

    So, how much sap weight can a vacuum support? If a foot of 3" PVC is required for each inch of vacuum, then can I assume that 1" of vacuum can support 1.5"*1.5"*PI*12"*0.004329 gallons/cubic inch* 8.333 lbs/gallon = 3.06 pounds of liquid? If 17" of vacuum is desired, then the weight of the column will be 17'*3.06 lbs/foot, or 52 lbs at equilibrium? If this is the case, then can I assume that a pipe that is 8" wide would only need to be 6' high (2.86' for the sap column + the 3' safety buffer)? Mr. Wizard, help!!

  2. #2
    Join Date
    Nov 2004
    Location
    Fall Creek, WI Woods: Lincoln/Price Counties, WI
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    155

    Default

    Sorry guys, I forgot to log in before posting the previous message.
    Russell Berg
    Mount View Sugar Bush - Since 1989
    2004 5.5' x 18' Custom-built Stainless Evaporator w/ 7' Piggyback + Preheater
    4,000 - 5,000 taps vacuum/gravity/bags
    24' x 32' Sugar Shack

  3. #3
    syrupmaker Guest

    Default

    I can't find the emoticon with a guy waving his hand over his head?

    Wow Russ.... i have never heard of anything such as that but it does sound interestingly possible. :idea: I'll have to reread your post and draw it out on paper to put it into perspective.

    Back to ya shortly :wink:

    Rick

  4. #4
    Maple Hill Sugarhouse Guest

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    post edited
    Last edited by Maple Hill Sugarhouse; 12-01-2008 at 07:53 AM.

  5. #5
    Join Date
    Nov 2004
    Location
    Fall Creek, WI Woods: Lincoln/Price Counties, WI
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    155

    Default

    Kevin:

    The mainline fittings go into the PVC pipe, 3-5' from the top. The vacuum line goes into the PVC at the very top. The drum is not sealed at all, it is merely there to provide storage for the start-up sap (priming sap?) required to seal the bottom of the PVC pipe. Otherwise you would just be sucking air in from the bottom.

    Hope this helps clarify the design.
    Russell Berg
    Mount View Sugar Bush - Since 1989
    2004 5.5' x 18' Custom-built Stainless Evaporator w/ 7' Piggyback + Preheater
    4,000 - 5,000 taps vacuum/gravity/bags
    24' x 32' Sugar Shack

  6. #6
    Maple Hill Sugarhouse Guest

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    post edited
    Last edited by Maple Hill Sugarhouse; 12-01-2008 at 07:53 AM.

  7. #7
    Join Date
    Apr 2003
    Location
    COLDEN, NY
    Posts
    349

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    YA WHAT HE SAID :wink: :roll:
    I've talked to farmers and syrup makers that use zero tanks. They have colapsed tanks with 17" vacuume or more. They run 15" vacuum in the tanks at the farms milking. Word of warning.

  8. #8
    Join Date
    Nov 2004
    Location
    Fall Creek, WI Woods: Lincoln/Price Counties, WI
    Posts
    155

    Default

    Thanks for the warning... that hasn't been a problem so far, but I don't know how much vacuum is typically on our systems. We have to get better at monitoring that.
    Russell Berg
    Mount View Sugar Bush - Since 1989
    2004 5.5' x 18' Custom-built Stainless Evaporator w/ 7' Piggyback + Preheater
    4,000 - 5,000 taps vacuum/gravity/bags
    24' x 32' Sugar Shack

  9. #9
    Join Date
    Nov 2003
    Location
    Cabot Vt
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    449

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    Hey now here's an idea i can get into- cheap and apparently effective! Does it really work though? I get the physics of it, but I'm left wondering if there's something left out of the equation that would screw up the whole operation. Some assumptions\questions.........Lets say its going to freeze hard overnightand there's that sap in the mainline that's going to stay there due to the height of this contraption- how about putting a T up to the releaser and a valve to let things drain out overnight? How 'bout if you build the version of this with 8 or 10 inch pipe so it is significantly shorter- that way you dont need T and valve if you can still run your mains into the releaser with slope. Am I on the right track here and most importantly, will it work as well as the expensive "store bought" releasers, because if it does, I'll start tomorrow. More thoughts, guys?
    4X12 A+A Evaporator
    2500 taps, 1200 GPH RO
    Atv w/tracks
    5 generations
    http://www.talbertsmaplefarm.com/
    https://www.facebook.com/TalbertsMapleFarm?ref=hl

  10. #10
    Maple Hill Sugarhouse Guest

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    post edited
    Last edited by Maple Hill Sugarhouse; 12-01-2008 at 07:53 AM.

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