Author Topic: Improved Refractometer Correction calculator  (Read 6785 times)

Offline tommymorris

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Re: Improved Refractometer Correction calculator
« Reply #60 on: February 05, 2018, 01:44:17 AM »
FWIW, I love my hydrometer and use it for OG and FG. I generally don’t know how accurate it is. Ball park is close enough for me.

I did check it against my hydrometer today. The Refractometer + BeerSmith calculator matched a hydrometer for the FG of a batch of blonde ale.

Offline klickitat jim

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Re: Improved Refractometer Correction calculator
« Reply #61 on: February 05, 2018, 03:11:11 AM »
Numbers
Cleaned and calibrated every sample
All hydrometer numbers corrected to temp
1.020 3x always 4.6°      .91
1.028 3x always 7.4°    1.04
1.050 3x always 13.4°  1.08
1.067 3x always 16.6°  1.01
1.088 3x always 21°       .99
1.102 3x always 25°     1.03
My correction factor is 1.012

Proved to me that my refractometer is always steady, and much easier to read a precise number. If I get different readings from a single wort, it's not homogenous!

I will be putting this to the test, with a few hydrometer checks to see how close I get.

Good stuff! Thanks again guys!

Offline Robert

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Re: Improved Refractometer Correction calculator
« Reply #62 on: February 05, 2018, 03:18:00 AM »
Numbers
Cleaned and calibrated every sample
All hydrometer numbers corrected to temp
1.020 3x always 4.6°      .91
1.028 3x always 7.4°    1.04
1.050 3x always 13.4°  1.08
1.067 3x always 16.6°  1.01
1.088 3x always 21°       .99
1.102 3x always 25°     1.03
My correction factor is 1.012

Proved to me that my refractometer is always steady, and much easier to read a precise number. If I get different readings from a single wort, it's not homogenous!

I will be putting this to the test, with a few hydrometer checks to see how close I get.

Good stuff! Thanks again guys!
Jim, you mean your AVERAGE wort correction is 1.012, right?  I was getting consistent results AT EACH gravity, it just varied so wildly between gravities.  I don't think I could just average the correction, I'd have to make a table of corrections at every possible gravity.  This seems absurdly untenable, unless I'm really missing something?
Rob
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Offline klickitat jim

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Re: Improved Refractometer Correction calculator
« Reply #63 on: February 05, 2018, 03:28:18 AM »
It's all done by the excell sheet, so I don't know. But it's 3 separate but identical readings at each gravity. The correction factor is the same at each gravity. Different at different gravities, I don't claim to know why, but that IS why it takes readings at different gravities to come up with the average. I'm not at all freaked out about it because it works, according to people far smarter than me. Sean Terril, if I recall correctly, is a nuke tech.

Trust, but verify. I'll try it out and compare with hydrometer samples.

FYI, I did 3 years at each gravity because brewers friend suggested 5... 3 is more than 1... 5 seemed too much, especially since they were all the same.
« Last Edit: February 05, 2018, 03:45:28 AM by klickitat jim »

Offline Robert

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Re: Improved Refractometer Correction calculator
« Reply #64 on: February 05, 2018, 03:48:33 AM »
It's all done by the excell sheet, so I don't know. But it's 3 separate but identical readings at each gravity. The correction factor is the same at each gravity. Different at different gravities, I don't claim to know why, but that IS why it takes readings at different gravities to come up with the average. I'm not at all freaked out about it because it works, according to people far smarter than me. Sean Terril, if I recall correctly, is a nuke tech.

Trust, but verify. I'll try it out and compare with hydrometer samples.
Exactly,  trust but verify.  The problem I have is the verify part looks like a PITA, and I'd have to have that because it just doesn't look right to my smaller-than-Terril's brain that the factor should jump all over like that... think I'm back where I started.  Hydrometer don't lie.   :D
Rob
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Offline Robert

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Re: Improved Refractometer Correction calculator
« Reply #65 on: February 05, 2018, 03:52:51 AM »
^^^^
Just realized: spreadsheet? Your Excel problem is solved, then?

And which spreadsheet are you using?  The one in Brewer's Friend that wants 30 samples?!
« Last Edit: February 05, 2018, 04:11:26 AM by Robert »
Rob
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Offline klickitat jim

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Re: Improved Refractometer Correction calculator
« Reply #66 on: February 05, 2018, 04:24:54 AM »
Brewers Friend one worked for me. Sean's wouldn't cooperate and as I looked at it, it wasn't the one for determining correction factor.

Offline dmtaylor

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Re: Improved Refractometer Correction calculator
« Reply #67 on: February 05, 2018, 12:03:06 PM »
I don't think the correction factor should be jumping around by that much.  When I was determining my factor, it ranged from about 0.94-0.99 but never so far out of whack to be in the 1.0's or 0.8's.  With experience I determined I needed to zero the gauge with water more often because readings would creep.  So I measure water both before AND after reading the wort.  Did you do that?  It could explain the degree of bounciness you were seeing in the factor.  Try to get the range tighter before declaring "1.012".

Also in science there is something known as an anomylous result or outlier, which is a result so odd that it is thrown out.  The 0.91 in your results appears wildly anomylous and should probably be tossed out if you cannot duplicate it.
« Last Edit: February 05, 2018, 12:07:57 PM by dmtaylor »
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Offline Robert

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Re: Improved Refractometer Correction calculator
« Reply #68 on: February 05, 2018, 12:36:46 PM »
^^^^
For me at least, yes, calibrated and had to make  no adjustments.  Water steady, wort bouncy.   Hydrometer trusty.
Rob
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Offline klickitat jim

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Re: Improved Refractometer Correction calculator
« Reply #69 on: February 05, 2018, 01:37:00 PM »


I don't think the correction factor should be jumping around by that much.  When I was determining my factor, it ranged from about 0.94-0.99 but never so far out of whack to be in the 1.0's or 0.8's.  With experience I determined I needed to zero the gauge with water more often because readings would creep.  So I measure water both before AND after reading the wort.  Did you do that?  It could explain the degree of bounciness you were seeing in the factor.  Try to get the range tighter before declaring "1.012".

Also in science there is something known as an anomylous result or outlier, which is a result so odd that it is thrown out.  The 0.91 in your results appears wildly anomylous and should probably be tossed out if you cannot duplicate it.

Cleaned and calibrated before each sample, which means after as well... remove the outliers and it's 1.02

The variance is not my refractometer, it's the interpretation of where the interface is on the hydrometer.

I also think it's much ado about nothing. The difference of correction between the ouyliers in a high gravity wort where the most change would show... If I stick with what I got, a 20BrixWRI reading is corrected to 19.8°/1.083 If I remove the outliers it's 19.6/1.082. In a normal gravity beer 15BrixWRI swings wildly from 14.8°/1.061 to 14.7°/1.061....

I'm happy with what I've learned and my results. Thanks again

Offline Phil_M

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Re: Improved Refractometer Correction calculator
« Reply #70 on: February 05, 2018, 01:53:04 PM »
So I'm thinking. Long ago when I got my refractometer it was reliable.  Then at some point it seemed to become anything but (this little test confirms that's still the case) so I just stashed and forgot it. Wonder if anyone knows of them just going bad?  (It is a <$100 model.)

I don't know about others, but I've noticed that when measuring hot wort evaporation plays a HUGE part in the final reading. If this was about FG readings, then disregard.
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Offline Big Monk

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Re: Improved Refractometer Correction calculator
« Reply #71 on: February 05, 2018, 01:55:49 PM »
So I'm thinking. Long ago when I got my refractometer it was reliable.  Then at some point it seemed to become anything but (this little test confirms that's still the case) so I just stashed and forgot it. Wonder if anyone knows of them just going bad?  (It is a <$100 model.)

I don't know about others, but I've noticed that when measuring hot wort evaporation plays a HUGE part in the final reading. If this was about FG readings, then disregard.

I usually cool the samples by inverting the dropping and putting the bulb in a container of chilled water. Doesnt take long and gives me more consistent results. Also, the quality of the sample (bubbles, clarity, etc.) plays a role too.
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Offline Robert

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Re: Improved Refractometer Correction calculator
« Reply #72 on: February 05, 2018, 01:55:58 PM »
So I'm thinking. Long ago when I got my refractometer it was reliable.  Then at some point it seemed to become anything but (this little test confirms that's still the case) so I just stashed and forgot it. Wonder if anyone knows of them just going bad?  (It is a <$100 model.)

I don't know about others, but I've noticed that when measuring hot wort evaporation plays a HUGE part in the final reading. If this was about FG readings, then disregard.
I'd expect that to consistently cause error on the high side, which is not happening here. 
Rob
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Offline klickitat jim

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Re: Improved Refractometer Correction calculator
« Reply #73 on: February 05, 2018, 02:23:55 PM »
What prompted me to pursue this was learning that suspended solids (yeast, hop matter, proteins etc) can render a hydrometer to be inaccurate by as much as 10 gravity points. That's no bueno. So how to confirm it's accurate? These solids don't effect refractometer accuracy, sooooo here I am. Plus less is needed for a reading. Plus it's much easier to see where the line is, at least for my eyes. Just explaining why I'm doing this, not trying to change anyone.

Offline Big Monk

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Re: Improved Refractometer Correction calculator
« Reply #74 on: February 05, 2018, 02:26:40 PM »
Plus less is needed for a reading.

This was a biggie for me. I'm only putting 1.25 gallons into the fermenter and I don't recycle gravity samples so a hydrometer is a no-go for me.
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