New Refractometer Correction

Discussion in 'Feature Requests' started by flyingbeer2, Jul 14, 2017.

  1. flyingbeer2

    flyingbeer2 New Member

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    Hi,

    have you considered a brand new refractometer correction from the current issue of Zymurgy magazine? It is proved to be more accurate, reliable than Terrill's formula and also useful for fermenting wort...

    I would highly appreciate that at least as an option!

    Thanks and cheers!
     
  2. Myndflyte

    Myndflyte Active Member

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    Just read the article yesterday. I mean if you base your decision on the graph that he plotted, then yeah, it looks like his method is more accurate than what's out there. It was an interesting read for sure and I'm going to start using that method with my refractometer.
     
  3. flyingbeer2

    flyingbeer2 New Member

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    That is not exactly true, the graph he plotted shows "just a validation" of the method if you find the original paper that the method is based on, you will find professional scientific data that are based on hundreds of data points from a professional brewery (Czech Budejovice Budvar). So, from that point of view, it is a reliable source. Anyway, you can make your own validation as he did and easily find out. I did mine and no offence to Terrill's work but it is a different level, works perfectly for me!
     
  4. Nosybear

    Nosybear Well-Known Member

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    That's the way I read it, too. For now, I'm doing the corrections and calculations by hand but in the future I'll work from a spreadsheet calculator and monitor progression of my fermentations using the refractometer. I can make more informed decisions about, say, when to start ramping up temperature on my lagers and that'll ultimately improve the beer.
     
  5. Nosybear

    Nosybear Well-Known Member

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    I've been tracking a fermentation and yesterday checked it with the finishing hydrometer. The corrected, calculated refractometer gravity was 1.0106, the hydrometer read the 55 degree sample at 1.011. I've been using a conversion table to convert SG to Brix and apparently the table has the wort correction factor (1.04) built in. The calc's are correct when I don't use the factor. And a difference of 0.4 points is close enough for me.
     
  6. Nosybear

    Nosybear Well-Known Member

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    Any chance we could move this over to General Discussions? Some info in here might be of interest to the rest of the forum.
     
  7. Yooper

    Yooper Administrator
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    I suggest starting a new thread there, with the information from here. Since we are kicking around features all the time, including this one, it does "fit" in the feature request and it's a good mark of how many requests we get for certain features. We want to remain as accurate as possible, so new ideas about our features are always welcome.
     
  8. Nosybear

    Nosybear Well-Known Member

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    Yooper, can you "clone" it? There's a lot of discussion here and I don't want to retype....

    P. S. The beer I mentioned earlier finished at 1.009 on both the refractometer after calculation and the hydrometer. I'm sold on using my refractometer for tracking fermentation based on this result using the calculations in the last edition of Zymurgy Magazine. I can reproduce them for the forum when I get home.
     
  9. Nosybear

    Nosybear Well-Known Member

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    Another update: I've checked the Zymurgy calculations against several more batches - spot on every time. The conversions are so good that I may just retire my hydrometer! One more thing to be aware of is the wort correction factor. I've been using a table even though my refractometer reads in Brix. If I use the Brix reading from the refractometer, I have to apply the wort correction factor. Using the table, I do not. So something along the lines of a converter using the refractometer correction factor from the profile should be good, the equation only has three variables (OG in Brix, Measured gravity in Brix, Wort Correction factor). Or use our favorite metric of gravity, specific gravity, convert to Brix. Either way, it shouldn't be hard to do.
     
  10. Yooper

    Yooper Administrator
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    I brought this up with the developer today; I'll let you know when we can do this.
     
  11. Yooper

    Yooper Administrator
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    My wort correction factor isn't 1.040- maybe yours is(?), but it's an average guestimate. My bet is that if you used your own correct wort correction factor, it may be spot on. My own wort correction factor is 1.02861. Being the OCD type, I know it's not far from 1.040, but still...........:)

    I don't get the paper zymurgy, only the digital, and I'm having trouble reading it on my iPad. I'm trying to explain the formula to the developers, and it's hard to do when I don't have it to show!

    Is there a way to link/copy the formula for us, without any copyright infringement? I didn't see in the article how to reference the original formula and data, but it was very difficult to read on my desktop and impossible on my iPad.
     
  12. Nosybear

    Nosybear Well-Known Member

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    Mine's 1.043 and a lot more decimal places. I don't have the formula with me here at work (yep, stealing a little time from the boss). Will post it when I get back home this evening. I'll also get you the formula for the wort correction factor.
     
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  13. Nosybear

    Nosybear Well-Known Member

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    Step 1 to the equation: Converting SG to Brix using the formula:

    Brix = (((182.4601 * SG -775.6821) * SG +1262.7794) * SG -669.5622)

    Brix = the density in Brix
    SG = the specific gravity from the hydrometer


    When measuring using the refractometer:
    Actual Brix = Measured Brix/WCF

    WCF = Wort Correction Factor (usually around 1.04, calculate for individual refractometers)
     
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  14. Nosybear

    Nosybear Well-Known Member

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    Yooper, here are the rest of the formulas:

    Gravity = 1 + 0.006276 * Brix (measured and corrected) - 0.002349 * Brix (original gravity)
    ABW = 0.67062 * Brix (Original) - 0.66091 * Brix (Measured and corrected)
    ABV = (FG * ABW)/0.791

    To find the refractometer correction factor, measure and calculate the FG using the equation using the refractometer. Then take the same reading with the hydrometer. The ratio of the refractometer result to the hydrometer result (use either points or Brix for this) is your correction factor. Note that if you use a SG - Brix conversion table, the correction factor may be already applied and your correction factor may turn out to be 1.
     
  15. flyingbeer2

    flyingbeer2 New Member

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    Any progress on that? Looks that you have everything that you need for successful implementation. I don't want to calculate it on paper anymore :)
     
  16. Yooper

    Yooper Administrator
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    Not yet! I'll let you guys know when we have this in place.
     
  17. Nosybear

    Nosybear Well-Known Member

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    I did it in Excel. I can post the file later as an interim solution.
     
  18. Sune Pedersen

    Sune Pedersen New Member

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    That would be a great addition!
     
  19. flyingbeer2

    flyingbeer2 New Member

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    I don' get it. What kind of improvement have you done now? "Improved accuracy of post-fermentation refractometer reading calculations in higher ABV beers" so it uses for high ABV beer Sean Terrill's linear formula now??? Why did you not upgrade the formula to the new one completely as we were talking about? That new formula has no problems with high ABV beers neither with beer during the fermentation, for that kind of beers the Terrils formulae is awful and will be. I don't see any point in tweaking it in anymore when a better method is out there...
     
  20. Josh (Brewer's Friend)

    Josh (Brewer's Friend) Administrator
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    Hi guys, Josh here (one of the developers).

    I'm really sorry for the miscommunication on this - totally my fault. I really appreciate all the info you've provided in this thread. I took another crack at implementing the formula above tonight.

    If you'd be up for it, I'd love for you to give it a try before it goes live. Visit this URL to try the new one:
    https://www.brewersfriend.com/refractometer-calculator/?new=1
    (make sure it has the ?new=1 at the end)

    Please let me know if you notice anything inconsistent with the way you've been applying the formulas. If it looks good, we can get this live and applied to the rest of the site too.
     

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