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Thread: Calculation for Sap before draw off

  1. #1
    Join Date
    Apr 2009
    Location
    Margaretville, NY
    Posts
    148

    Default Calculation for Sap before draw off

    I was having a debate last night with my buddy about why we had enough sap to make 25 gallons of syrup and we only drew off 18. I told him that it takes a bunch of gallons to fill the machine and then a bunch more to evaporate until the first draw and that is our differance. I could find this out a couple of ways. 1 Actually measure how many gallons I used from fill to draw. 2 Pull all the sap from the evaporator measure the volume and sugar content and calculate how many gallons it took to get there. Does anyone have a calculation based on size of the evaporator for this number?
    Millbrook Maple
    Catskill Mountains
    Store - Arkville, NY
    Saphouse - Somewhere in witness protection area.
    2.5 X 8 1990 Grimm Lightning
    600 GPH RO
    2000 Taps and growing each season
    30 Buckets
    Always looking for more sap!

  2. #2
    Join Date
    Jan 2008
    Location
    Frankford, Ontario
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    Default

    I'm assuming this is a first boil and you were filling the evaporator and sweetening it as part of the process.

    Below is the math to determine how much sap is required to sweeten pans. For your purposes, subtract this amount from your starting sap quantity and then divide the remainder by your sap:syrup ratio to see how much you will actually produce. Once sweetened - all subsequent boils will produce at your normal sap:syrup ratio.

    Working in metric units.

    Number of litres to fill the pans = [(evap width in cm x evap length in cm x usual depth in cm) + (Num Flues x width of flues x depth of flues x length of flues)] all divided by 1000

    Sap to sweeten pans = Number of litres x sap:syrup ratio / 2

    Convert to US gallons by dividing by 3.78 l / 1 US Gal



    Example - running 1.5" deep on a 2x6 with a 4' drop flue pan (6 flues 7" deep by 1" wide)

    Volume =[ 60cm wide x 182cm long x 4cm deep + 6 flue x 2.5cm wide x 120 cm long x 18 cm deep ] / 1000
    _______= [43680 + 32400 ] /1000
    _______= 76 litres or 20 US gals

    Assuming a 40:1 ratio.
    Sap to sweeten = 76l *40 / 2
    ______________= 1520 litres or 400 US gals.


    The calculations above are based on a continuous flow process with an evaporator design that permits establishing an even gradient through the evaporator. Any mixing between sections will increase the amount of sap required before the first draw off. If you have no flues in your pan, just use 0 for the number of flues and the rest is the same.
    Last edited by Big_Eddy; 03-20-2013 at 08:13 AM.
    Big_Eddy
    Eastern Ontario (Quinte)
    20+ years on a 2x3 block arch,
    Homemade 20"x64" drop flue since 2011

    Build a Block Arch
    Build a Flat Pan
    Build a Flue Pan
    Sweetening the Pans
    Build a Bending Brake
    Using a Hydrotherm
    How much Sap to Sweeten?

  3. #3
    Join Date
    Mar 2011
    Location
    Broad Brook, Connecticut
    Posts
    540

    Default

    What does it mean to sweeten the pans? I always thought it was just slang for the first boil of the year.
    2011-8 Taps on a very crude block arch
    2012- 38 taps 2 X 3 with blower.
    2013- 70 taps total-50 on tubing, 20 on buckets
    2014- 75 taps- Low vacuum, 2X4 drop flue
    2015- 100 taps-2X6 Mason Drop Tube, low vac
    2016-115 taps high vac, 60 taps buckets
    14X20 post and beam shack with attached 10X14 wood shed
    12 beehives and an avid waterfowl hunter.
    Wishing I can quit my day job, keep bees, farm, and make syrup!
    https://www.facebook.com/pages/Moshe...40072296064422

  4. #4
    Join Date
    Jan 2008
    Location
    Frankford, Ontario
    Posts
    1,008

    Default

    Starting Small.

    In a continuous process, the pans are not emptied at the end of each boil, rather the "sweet" is left in the pans for the next boil.

    Sweetening the pans refers to the first boil, where the pans start with raw sap throughout, then as you boil and boil and boil without any drawoffs, the gradient develops in the pans until you have raw sap at the inlet and "almost syrup" at the outlet. For a 2x6, this is roughly 400 gals of sap boiled down without any syrup produced and can be up to 20 hours of boiling.

    Once the gradient is in place, then syrup starts to flow out at the usual ratio i.e. for every 40 gals boiled off, 1 gal is produced.

    After each boil, we allow the rig to cool and close the valves between sections to maintain the gradient. Then when we start up the next day, the gradient is already there and syrup is produced "right away".

    The pans are only emptied at the end of the season or for cleaning, and afterwards the gradient needs to be established again.
    Big_Eddy
    Eastern Ontario (Quinte)
    20+ years on a 2x3 block arch,
    Homemade 20"x64" drop flue since 2011

    Build a Block Arch
    Build a Flat Pan
    Build a Flue Pan
    Sweetening the Pans
    Build a Bending Brake
    Using a Hydrotherm
    How much Sap to Sweeten?

  5. #5
    Join Date
    Mar 2011
    Location
    Broad Brook, Connecticut
    Posts
    540

    Default

    The more I learn the more I realize how little I actually know! Thanks for that, it makes more sense now.
    2011-8 Taps on a very crude block arch
    2012- 38 taps 2 X 3 with blower.
    2013- 70 taps total-50 on tubing, 20 on buckets
    2014- 75 taps- Low vacuum, 2X4 drop flue
    2015- 100 taps-2X6 Mason Drop Tube, low vac
    2016-115 taps high vac, 60 taps buckets
    14X20 post and beam shack with attached 10X14 wood shed
    12 beehives and an avid waterfowl hunter.
    Wishing I can quit my day job, keep bees, farm, and make syrup!
    https://www.facebook.com/pages/Moshe...40072296064422

  6. #6
    Join Date
    Jan 2008
    Location
    Frankford, Ontario
    Posts
    1,008

    Default

    The above is primarily designed for a flue pan, where the sweet is left in from run to run.

    Don't think your Mason 2x3 has flues, so you can run it either as a batch process or as a flow process assuming you have dividers in it.

    A 2x3 without dividers needs about 70-80 gals to make a batch. Start out about 2"-3" deep and just keep adding and adding as sap evaporates until all 70 gals are in, then reduce until you have about 1/2" in the bottom and that's pretty close to syrup. Let the fire go down when you're at 3/4", and pour it off into a pot before you get to 3/8". Finish on propane or stove.

    A 2x3 with dividers run as a continuous process will evaporate about 40 gals of sap before you're ready to take your first draw, after which you can take off maybe a quart at a time every 2 hours or so. Before the end of the day, you need to decide if you're going to finish everything in the pan, or leave the sweet in the pan for tomorrow. Typically the sweet would be left in.

    If you want to finish it all, then you switch back to batch mode and mix the pan around so that you have an even concentration throughout the pan, then reduce it all from there. Make sure you have enough sap when you switch modes to ensure that you're still 1/2" deep when done.
    Big_Eddy
    Eastern Ontario (Quinte)
    20+ years on a 2x3 block arch,
    Homemade 20"x64" drop flue since 2011

    Build a Block Arch
    Build a Flat Pan
    Build a Flue Pan
    Sweetening the Pans
    Build a Bending Brake
    Using a Hydrotherm
    How much Sap to Sweeten?

  7. #7
    Join Date
    Mar 2011
    Location
    Broad Brook, Connecticut
    Posts
    540

    Default

    That is terrific information, I really appreciate it. It does have dividers so there are three compartments for continuous flow. I will probably leave the sweet in the pan. Can I leave the sweet there if I am not able to evaporate the next day? Would it keep alright for 2 or 3 days between boils?
    2011-8 Taps on a very crude block arch
    2012- 38 taps 2 X 3 with blower.
    2013- 70 taps total-50 on tubing, 20 on buckets
    2014- 75 taps- Low vacuum, 2X4 drop flue
    2015- 100 taps-2X6 Mason Drop Tube, low vac
    2016-115 taps high vac, 60 taps buckets
    14X20 post and beam shack with attached 10X14 wood shed
    12 beehives and an avid waterfowl hunter.
    Wishing I can quit my day job, keep bees, farm, and make syrup!
    https://www.facebook.com/pages/Moshe...40072296064422

  8. #8
    Join Date
    Dec 2007
    Location
    Overseas
    Posts
    25

    Default

    Thanks for sharing Big_Eddy.

    I made an online sap volume calculator based on the formula you posted.

    By the way, in case anyone is wondering why the numbers are off using the example posted by big_eddy. It's because of how we rounded off numbers. The spreadsheet used up to 2 decimal places in all calculations, while in eddy's formula he just dropped those numbers off.
    Last edited by GOwin; 03-23-2012 at 10:39 AM. Reason: corrected URL

  9. #9
    Join Date
    Sep 2012
    Location
    Dresden, ME
    Posts
    163

    Default

    GOwin,
    Am I missing something? I tried the calculator but it doesn't allow me to change the blue numbers.
    2010 - barrel stove & a steam table pan. 10 - 12 trees
    2011 - same deal as the year before. My son is now hooked along with me.
    2012 - Took over the garden shed and set up a Mason 2x3. Hoping to tap 30 - 50 trees. Ended up with 100 taps out.
    Finished the season with 16 gallons made
    2013- - Purchased a Smokey Lake 2 x 3 Hybrid pan. WOW, what a difference!!

  10. #10
    Join Date
    Jan 2011
    Location
    Belchertown, MA
    Posts
    181

    Default

    sg5054 you have to download to your PC and use in Excel.
    John

    2 x 8 custom arch, custom raised flue pan, AOF/AUF, custom auto draw off and other automation
    400 taps (buckets and tubing)
    18 x 24 timber frame shack
    Two daughters that are a LOT of help
    Greyhound that drinks sap (and has gas)
    2011 Gator 825 XUV with 100 gallon tank
    5 275 gallon IBC totes for storage

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