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Thread: shurflo question- no vac readings on a no flow day

  1. #11
    Join Date
    Apr 2008
    Location
    Jacksonport Wisc
    Posts
    4,677

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    I stand Corrected because not one post mentioned shutting down the flow after higher vacuum levels were achieved.
    3X10 Lapiere Waterloo small/CDL raised flue with oil fired homemade steam hood
    1200 plus taps all on vacuum thru sap ladders
    Smoky Lake Maple products Great lakes Guardian auto draw off
    Custom 2X4 finish pan by Mosie/Derrick
    Kubota BX 2370 tractor and Polaris ATV
    CDL Airtech L63
    2 double Bernard releasers
    Westfab 7" short bank
    More dang tanks and pumps than I can remember
    10-14 bee hives give or take
    Yellow dog made from parts named Roxy

  2. #12
    Join Date
    Apr 2008
    Location
    Jacksonport Wisc
    Posts
    4,677

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    Now that brings up another dilemma. If you have an over sized pump for the capabilities of the tubing system you are building in the NOT ENOUGH LIQUID to run the system and you will always have cavitation lowering your vacuum levels...................Right??
    3X10 Lapiere Waterloo small/CDL raised flue with oil fired homemade steam hood
    1200 plus taps all on vacuum thru sap ladders
    Smoky Lake Maple products Great lakes Guardian auto draw off
    Custom 2X4 finish pan by Mosie/Derrick
    Kubota BX 2370 tractor and Polaris ATV
    CDL Airtech L63
    2 double Bernard releasers
    Westfab 7" short bank
    More dang tanks and pumps than I can remember
    10-14 bee hives give or take
    Yellow dog made from parts named Roxy

  3. #13
    Join Date
    Mar 2006
    Location
    Eden Prairie, MN
    Posts
    1,457

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    Not really the case

    A diaphragm pump will have an optimum flow rate for generating vacuum, where the fresh sap flow rate is far below the full open flow rating of the pump. Open flow rate is 3 or 3.5 gpm on a shurflo, or 180 gallons per hour. Nobody is going to have that many taps on a little pump like that, so we will always be operating well below the open flow rate. I haven't done detailed tests, but I have about 50 taps on my shurflo, and on a great run I suppose it might flow 100 gallons over a 10 hour period, or less than 0.2 gpm. Thats plenty of flow for keeping the diaphragm wet and working well. You can see that a little recirculation throttled in could maybe double or triple that flow through the pump and still be well below the open flow rating. So even if you leave the recirculating line open on good days, it still works ok, and is there to fill in if the trees slow down.

    There will always be some bubbles in the lines, always some air going through the pump, but the recirculation line keeps something in the pump when things slow down.
    John
    2x8 Smokylake drop flue with AOF/ AUF
    170 taps on sacks
    50 on 3/16 tubing with shurflo
    Eden Prairie, Minnesota

  4. #14
    Join Date
    Apr 2017
    Location
    Central Maine
    Posts
    66

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    No offense, but my original question is still unanswered. Can I just tap the out going line on the pump side or should I run a line back from my collection tank. I really can't see any difference.
    2017- Started small- 90 taps and made 7 gallons. Long days and a few nights on a 1x2 and turkey fryer. Did a lot of reading. Caught the bug!

    2018- Bought a homebuilt 2x4 and built a small scale RO. # of taps? More then last year, 225, maybe more, with about 90 on vacuum.

  5. #15
    Join Date
    Mar 2006
    Location
    Eden Prairie, MN
    Posts
    1,457

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    Quote Originally Posted by Mark B View Post
    No offense, but my original question is still unanswered. Can I just tap the out going line on the pump side or should I run a line back from my collection tank. I really can't see any difference.
    Got distracted I guess!

    I have multiple suction lines and drop one into the tank for recirculating, with a needle valve to limit flow. If you pull off your outlet line you risk not having a steady Source in low flow situations, which is when you want to assure a wet pump.
    John
    2x8 Smokylake drop flue with AOF/ AUF
    170 taps on sacks
    50 on 3/16 tubing with shurflo
    Eden Prairie, Minnesota

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