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Thread: Using a hydrometer and thermometer

  1. #1
    Join Date
    Feb 2017
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    Connecticut
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    Default Using a hydrometer and thermometer

    I'm curious if anyone has used both of these tools at the same time. I have only used a hydrometer. I've seen lots of videos, and it appears most small time boilers use thermometers. My question is, if you're using both, have you ever tested them at the same time? Float to the red line on the hydrometer and hit 119 degrees at the exact same time?
    Also interested in which method is favored to you.
    Thanks

  2. #2
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    Oneida NY
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    I have not, but I did use an Accu-Cup for several years before I got a Murphy cup. The Accu-Cup has a thermometer built in and it comes with a laminated chart to tell you what the hydrometer reading should be at various temperatures. One issue with that is how much to figure for temperatures in between the temps on the chart.
    For your info, if you actually get a reading of 219 (not 119) when testing your temperature of what you filled the test cup with was very likely well over 219. The reading will be essentially the same all of the way down to 211. That is why the red line is at 211.
    While it costs more to get a Murphy Cup (and a Gold series hydrometer) I have found it superior to any other I've used. The Murphy Cup in reality is a thermometer in the cup like an Accu-Cup, the difference is that the face of the thermometer has been replaced with a face showing exactly what your hydrometer should read at the temperature the contents of the cup in at. The Gold series hydrometer just has a line on the outer glass to verify that the paper inside has not moved (which would give you a false reading.)
    Dave Klish about 400 taps, down from much more. Retired from collecting and boiling in 2021. Mostly because of a bad hip.
    2012 Mahindra 36 HP 4x4/ loader/cab/heat/AC:-)
    3x8 raised flue evaporator
    250 GPH converted to electric, RO by Ray Gingerich
    6.32 KW solar system, 1.48KW is battery backed up, all net metered
    website: www.cnymaple.com

  3. #3
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    May 2009
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    Essex VT
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    Every drop of syrup that I produce, (1,243 gal in 2020) is checked with a hydrometer and a thermometer in about 6 gallon batches before the syrup is put through the filter press and then into SS barrels. After drawing off 6 gallons into a 7 gall SS pot, I place the pot on a propane burner set up, bring the temperature of the syrup up to 211 degrees and then check the density with my hydrometer. If the syrup is too heavy, I add hot sap to reduce the density to the hydrometer 211 red line.

    I have an automatic draw off that I set the draw off temperature on before each day's boil after checking the barometric pressure. I always set the draw off temperature a few tenths of a degree higher than my barometric pressure draw off temp chart that I made up. (To make sure that the initial draw of syrup is not too light) Once in a while, the only time the syrup is under density, is the first draw of the day's boil if I goof up the initial temp setting. If the initial draw syrup is too light, I just boil it a little on the propane burner to bring it up to density.

    Using this method also insures that all my syrup is started through the filter press at about 210 degrees.

    Joe
    2004- 470 taps on gravity and buckets
    2006- 590 taps on gravity and buckets 300 gph RO
    2009- 845 taps on vacuum no buckets, 600 gph RO
    2010- 925 taps on vacuum new 2 stage vacuum pump
    2014- 3045 taps on vacuum, new 1200 gph RO
    2015- 3104 taps on vacuum
    2017- 3213 taps on vacuum
    3' x 10' oil fired evaporator with steamaway

  4. #4
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    Apr 2011
    Location
    Fayston, Vt
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    Boil water first to establish degrees f then add 7.1 it should be close and hydrometer will then confirm+/-.
    2020 same
    2019 RB10 26 taps
    2018 RO Bucket RB5 taps 20, leg tank in shed w/2 5/16
    2017 18 taps
    2016 20 taps
    2015 21 taps
    2014 30 2 gravity line, 2 hotel pan concrete arch 35 g leg tank
    2013 LP hook up in shack buckets 12 taps
    2 burner cook top 2012 finisher on a bbq tanks
    2011 rookie 2+ gal
    8 taps w/ milk jugs
    turkey cooker
    50-60 up back maybe

  5. #5
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    Jan 2006
    Location
    Oneida NY
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    Once I got an auto draw, I ran it just 1 season before getting a Marcland barometer/boiling point of water meter. I bought it for $99 at the winter maple conference at the NYS fair grounds the first year it was there instead of at VVS in Verona. It made setting the correct draw temp far easier. I was surprised how often the pressure changes during the day, even when no weather changes are seen. I have gotten more consistent densities since using it. That does not mean I never need to do a correction in the finisher or bottler but those are in my opinion the result of additional evaporation after the syrup is drawn. I now verify density out of the finisher if sending the syrup thru the filter press directly to a SS barrel, if sending it to the bottler I test it after a good stirring from the bottler. Anyways, I now use that and I recheck several times during the day and reset as needed. I just checked Bascom, they now list it at $150. I don't recall if the $99 I paid was a show special, or did the price go up that much?
    Dave Klish about 400 taps, down from much more. Retired from collecting and boiling in 2021. Mostly because of a bad hip.
    2012 Mahindra 36 HP 4x4/ loader/cab/heat/AC:-)
    3x8 raised flue evaporator
    250 GPH converted to electric, RO by Ray Gingerich
    6.32 KW solar system, 1.48KW is battery backed up, all net metered
    website: www.cnymaple.com

  6. #6
    Join Date
    Apr 2019
    Location
    Nashville, MI
    Posts
    403

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    I like Maple Flats have the murphy cup and gold series hydrometer. This was what I started using when I got my new evaporator. I have an auto draw-off that I set just a little heavy and then will correct the density at the end of the day. I double check with the murphy cup and when I bottle.
    2004 - 2012 2x3 flat pan 25 to 60 taps
    2012 2x3 new divided pan w/draw off 55 taps
    2018 - didn't boil surgery - bought new evaporator
    2019 new SML 2x4 raised flue high output evap. 65 taps
    made 17 gal syrup
    2020 - only put out 53 taps - made 16.25 gal syrup
    2021 - going for 50 bags and 50 on tubing

  7. #7
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    May 2009
    Location
    UVM Proctor Maple Research Center, Underhill Ctr, VT
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    Like Dave, we currently use the Murphy Float (similar to the cup, but used in a drawoff tank) and Gold Series hydrometer. We used to use a digital stem thermometer in a cup, then went through a couple of versions of the Accu-Cup (which worked well) when we were using a finishing pan. The Murphy Float seems to be the quickest and easiest approach now that we're doing a lot more volume (typically we make 400-600 gal of syrup per boil).

    During a boil I use a standard hydrometer cup and Gold Series Hydrometer for syrup coming hot off the evaporator. Fill and empty the cup 2-3x off the evaporator, then fill the cup and float the hydrometer. No need to use a thermometer since the syrup is definitely between 211-219 deg F doing it this way. This works well for getting in the ballpark (actually comes pretty darn close).

    Once one side of the drawoff tank is full, we'll switch over into drawing off into the other side. Then we'll stir the full side of the tank well, put in the Murphy Float and Hydrometer and compare. Typically we'll draw a little heavy. If it is too much over, we'll add hot sap from the backpan to dilute back to proper density (this keeps the syrup hot enough to filter).

    Once we're correct for density we add DE, circulate through the filter press until clear, then send it off to the barrel. We'll typically do 4-5 barrels per press run, and these are all daisy-chained together via barrel fill devices. That accomplishes three things....1) we don't need to worry about a barrel overfilling, 2) any small variation in density is homogenized out since the syrup passes through several barrels and 3) everything stays really hot coming from the drawoff tank through the press and into the barrel.
    Last edited by maple flats; 10-19-2020 at 09:34 AM. Reason: Dr Tim, I fixed a typo, from 291 to 219
    Dr. Tim Perkins
    UVM Proctor Maple Research Ctr
    http://www.uvm.edu/~pmrc
    https://mapleresearch.org
    Timothy.Perkins@uvm.edu

  8. #8
    Join Date
    Feb 2017
    Location
    Connecticut
    Posts
    111

    Default

    Thanks to all. Let me be more specific. I am a backyard boiler making less than 5 gallons all season, and boiling less than 50 gallons at a time. I have seen people on videos similar to myself with a standard digital probe thermometer in a sauce pan on their kitchen stove. When the temperature on their thermometer reaches 219 degrees, they stop boiling and start finishing.
    I am using a standard glass syrup hydrometer and stainless steel testing tube I bought at tractor supply. I was asking if anyone has ever reached 219 degrees on their thermometer and then tested it with a standard glass hydrometer?
    I ask because sometimes I think I'm boiling too long, and my ratios are HORRIBLE compared to what I see on this site from others. I realize my maple trees aren't the best. They are just woods maples on my own property.
    I plan on doing my own experimenting using both methods at the same time, but thought I'd ask here in the meantime.
    And when I say HORRIBLE, I mean HORRIBLE!!

  9. #9
    Join Date
    Apr 2013
    Location
    Northeast Vermont
    Posts
    548

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    use the temperature measurement as a guide to when it's time to test your syrup with a hydrometer. the are a few factors to think about when determining if you have syrup... the hydrometer doesn't lie!
    Awfully thankful for an understanding wife!

    “The only place success comes before work is in the dictionary.”
    - Vincent “Vince” Lombardi

    Good luck to all!

  10. #10
    Join Date
    May 2009
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    UVM Proctor Maple Research Center, Underhill Ctr, VT
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    Quote Originally Posted by Gord View Post
    I am using a standard glass syrup hydrometer and stainless steel testing tube I bought at tractor supply. I was asking if anyone has ever reached 219 degrees on their thermometer and then tested it with a standard glass hydrometer?
    Is it a maple syrup hydrometer? How long have you been using it? Is it in decent shape (no cracks, no niter on it, paper hasn't shifted)? Has it ever been calibrated or checked recently? Are you measuring immediately after you draw off HOT from the evaporator? If it isn't really hot, you will need to simultaneously measure temperature (with a good thermometer) and apply the correction factor.

    The temperature won't stay at 219 deg F for long after you draw off, but if you dip the cup in the hot liquid or fill/dump/refill several times with hot syrup it won't cool as quickly. As long as the temp doesn't drop below 211 you'll get a good reading on the hydrometer (assuming it is in good shape and calibrated properly) doing this using the hot test (red) line on the hydrometer. Have you ever checked the syrup cold (using the cold test line, often blue)?

    Some tips at https://www.youtube.com/watch?v=vYAE...index=3&t=487s

    https://www.cdlinc.ca/wp-content/upl...hydrometer.pdf
    Last edited by DrTimPerkins; 10-19-2020 at 11:57 AM.
    Dr. Tim Perkins
    UVM Proctor Maple Research Ctr
    http://www.uvm.edu/~pmrc
    https://mapleresearch.org
    Timothy.Perkins@uvm.edu

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