Water Volumes and Temperature Correction

Discussion in 'Recipe Editor' started by Craigerrr, Dec 15, 2019.

  1. Craigerrr

    Craigerrr Well-Known Member

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    So the accepted water volume correction as I understand it is generally accepted as 4%. Does the recipe editor and the volumes referred to take this into account?

    For instance does preboil volume account for the thermal expansion of the usually 150F ish wort temperature?

    Similarly is post boil volume based on post cooling volume, or is the volume based on the corrected volume of 200F+ degree wort?
     
  2. Pricelessbrewing

    Pricelessbrewing QA Software Tester
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    I could be wrong, as I haven't done any audit or testing on this feature yet, but there's a user setting "Cooling shrinkage" in your equipment profile for this.

    https://www.brewersfriend.com/homebrew/profile/equipment

    As far as I understand it, the recipe editor calculates all volumes (including preboil, postboil, and boil off rate) at room temperature, and the brew session log allows for temperature corrections to a degree. The formula used is linear, according to the documentation.

    For those that like math...

    Engineering toolbox has a chart of volumetric temperature expansion of water, which is what I based my formula on. Note that there's likely a weak relationship with gravity that is currently ignored as there's no data to know how it works. Engineering toolbox's data has a coefficient of 1.043841 at standard temperature and pressure, and shows a R^2 value of ~94.7 for linear functions, but 99.93% for a 2nd degree polynomial with greater accuracy as more terms are added.
     
  3. Craigerrr

    Craigerrr Well-Known Member

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    Thanks Priceless.
    So, lets say that my recipe says preboil volume is 12.26 gallons. Is this calculating the theoretical room temperature wort volume (11.8) + 4% for thermal expansion?
    Or should I be taking the 12.26 + 4% (12.75) to determine what actual hot volume I should have in my kettle preboil?
    Mine is set at 4% by the way.
     
  4. thunderwagn

    thunderwagn Well-Known Member

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    You lost me at "I could be wrong" o_O
     
  5. Pricelessbrewing

    Pricelessbrewing QA Software Tester
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    The hot preboil should be 12.75.
     
  6. Nosybear

    Nosybear Well-Known Member

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    My guess: 4% is likely accurate enough.
     
  7. Craigerrr

    Craigerrr Well-Known Member

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    Okay thanks priceless.

    This raises another question though: What is the purpose of entering a value in the cooling shrinkage field in ones profile? What calculation, or function does this setting perform?
     
  8. Pricelessbrewing

    Pricelessbrewing QA Software Tester
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    It's used in the brew log entries in the various mash and boil entries under the volume section, click the checkbox for temperature correction and an input field temperature is displayed and an output for the adjusted volume.
     

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