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Thread: Vacuum releaser question?

  1. #1
    Join Date
    Feb 2012
    Grand Rapids, Michigan

    Default Vacuum releaser question?

    I have four hundred taps that I want to put under vac with a releaser. There will never be a possibility of more than four hundred and I want to know what size or type of vac would be best and do I go with single or double releaser. I somewhat new to the vacuum system and would appreciate any input you have.

  2. #2
    Join Date
    Mar 2013
    Hoosick Falls


    Most releasers are designed for a maximum number of taps...you are in luck you are in the mid range of most small releasers.

    What kind of pump are you looking for? High vac will get you the most production and best return on your investment. You can go with a water cooled liquid ring which will run well for hi vac for many seasons but brings a health price tag at check out time. The other end of the spectrum is a dairy pump. These pumps are originally run at 15" of vacuum to milk cows. Since we are harvesting sap we want higher vac to get more sap from the trees. 5-7%/ inch above 15". These don't cost as much.

    Personally I use a dairy pump that goes for around $500. I rebuilt it and modified it to run at 28". For a releaser I use a dairy style with an electric pump that removes the sap from the releaser. My new system is a teaching set up for kids and adults. It is much easier when they can see the sap coming in from the mains and going into the releaser and out to storage tanks. An injury has been running behind on remodeling our sugar house but with the brutal cold sub zero nights I am not concerned right now.

    The benefits of a electric sytle releaser is there is no back flow or drop in vacuum during the empting of the releaser; since the vacuum level is constant on the lines.
    When the releaser is nearly full the pump cycles on and removes sap to nearly empty. We ran a mechanical releaser for a short time and found it didn't work to our needs. Our old releaser that the glass one is replacing was a smaller stainless steel unit with a PVC manifold and vacuum reservoir. The reservoir or some times called a balance tank is always under vacuum and is of a large size so that when a releaser cycle occurs that vacuum does not drop drastically. This drastic drop in vac causes the back flow of sap in the mains that some people see. Some do not as the system cycles quickly and they have a large pump.

    For 400 taps on a tight system you will need 1 cfm(cubic feet per minute) of vacuum from the pump. In a less tight system 1 cfm/ 50 taps is recommended. Poorly seated taps will leak, fittings that are not slid on all the way will leak, saddles on the main lines(mains) can leak. If you have deer in the bush your saddles will leak and I would suggest a saddle like CDL's max seal and use the bolt lock. Deer love to rub on my saddles. All these little leaks add up.

    An under sized vacuum pump will not be able to get you to high vacuum consistently. You want high vac all the time the pump is running. It only takes a few minutes for the pump to evacuate all the air from the tubing system...as long as you don't have a bunch of small leaks or spout or two off. It is a great idea to check the lines when the sap is running for leaks.

    Good Luck!

  3. #3
    Join Date
    Nov 2010
    Barnet, VT


    Well said Breezy!
    900 taps plus 1200 purchased sap
    3 X 12 Thor pans on a Brian design arch
    1986 Seprotech 900 RO

  4. #4
    Join Date
    Sep 2003
    Whately, Ma.


    One more thing to add about the size of the vacuum pump is to look at the cfm curve. Most vacuum pumps are rated at "open flow" meaning 0"Hg. Then as the vacuum level is increased the cfm's go down. So if you can (not always easy on old dairy pumps)look at the cfm at 20" or 25" etc. The same thing goes for air compressors they are rated at a certain psi and the higher the pressure the lower the cfm
    I know some small producers who will get into vacuum by starting off with used dairy pumps and then after a few years with moderate vacuum will then buy a different pump and run high vacuum
    Really depends on your ability. Do you want to jump right in now full tilt or start off with what you can afford and then build as you go.

    Good luck either way.

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