Palmer Spreadsheet Error

Tue Dec 14, 2010 5:14 pm

After reviewing a water profile created by a brewer using Palmer's Spreadsheet, I found a very serious error that must be corrected.

The bicarbonate concentration calculated from the addition of chalk is in error. It appears that the calculation is actually giving the carbonate concentration instead of the bicarbonate concentration. Since carbonate cannot exist at typical mash pH, it must be converted to the bicarbonate form. That means that the carbonate concentration should be multiplied by 2.033. This also means that the alkalinity calculated for the chalk in the spreadsheet is also in error and should be multiplied by 2.033.

Another significant error in the spreadsheet is the residual alkalinity that the spreadsheet recommends based on the beer color. It is far too aggressive and recommends far too high a RA value to the brewer. There are no water profiles from the historic brewing centers with a RA higher than about 180. This spreadsheet will frequently point a brewer to recommended RA values of 300 to 400. That is extremely excessive and leads to soda water beers. A more appropriate correlation between RA and SRM is as follows: RA = SRM x 4.5. And given that correlation, the maximum RA a brewer should ever use is about 200.

Until the revised spreadsheet is issued, I recommend that brewers refrain from using this program.
Last edited by mabrungard on Wed Dec 15, 2010 5:48 am, edited 1 time in total.
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Re: Palmer Spreadsheet Error

Tue Dec 14, 2010 5:54 pm

mabrungard wrote:After reviewing a water profile created by a brewer using Palmer's Spreadsheet, I found a very serious error that must be corrected.

The bicarbonate concentration calculated from the addition of chalk is in error. It appears that the calculation is actually giving the carbonate concentration instead of the bicarbonate concentration. Since carbonate cannot exist at typical mash pH, it must be converted to the bicarbonate form. That means that the carbonate concentration should be multiplied by 2.033. This also means that the alkalinity calculated in the spreadsheet is also in error and should be multiplied by 2.033.

Another significant error in the spreadsheet is the residual alkalinity that the spreadsheet recommends based on the beer color. It is far too aggressive and recommends far too high a RA value to the brewer. There are no water profiles from the historic brewing centers with a RA higher than about 180. This spreadsheet will frequently point a brewer to recommended RA values of 300 to 400. That is extremely excessive and leads to soda water beers. A more appropriate correlation between RA and SRM is as follows: RA = SRM x 4.5. And given that correlation, the maximum RA a brewer should ever use is about 200.

Until the revised spreadsheet is issued, I recommend that brewers refrain from using this program.


I've noticed empirically that the chalk additions it calculates are woefully inadequate. That would certainly explain why.

As to the color / residual alkalinity thing, that's pretty well known. AJ is a big proponent of how wrong it is.
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thatguy314
 
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Re: Palmer Spreadsheet Error

Tue Dec 14, 2010 6:18 pm

Has AJ ever been on the session or brew strong? If not why not?
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Re: Palmer Spreadsheet Error

Tue Dec 14, 2010 8:05 pm

beltbuckle wrote:Has AJ ever been on the session or brew strong? If not why not?


He was on the color brew strong
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thatguy314
 
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Re: Palmer Spreadsheet Error

Tue Dec 14, 2010 10:12 pm

The bicarbonate concentration calculated from the addition of chalk is in error. It appears that the calculation is actually giving the carbonate concentration instead of the bicarbonate concentration. Since carbonate cannot exist at typical mash pH, it must be converted to the bicarbonate form. That means that the carbonate concentration should be multiplied by 2.033. This also means that the alkalinity calculated in the spreadsheet is also in error and should be multiplied by 2.033.


It wouldn't be the that the alkalinity calculated is off by 2.033, just the portion provided by the calcium carbonate. The sodium bicarbonate would still contribute 191 ppm HCO3 per gram per gallon, but the calcium carbonate should be corrected to add 321 ppm HCO3 per gram per gallon.

Right?
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Re: Palmer Spreadsheet Error

Tue Dec 14, 2010 10:35 pm

Also, the Beer Smith water calculator concurs with Palmers worksheet. It also adds 158 ppm HCO3 for each gram of CaCO3 per gallon.
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Re: Palmer Spreadsheet Error

Wed Dec 15, 2010 5:52 am

Bryantsbrewery is correct that the only the alkalinity calculated for the chalk addition is incorrect. The baking soda calculation is correct. I've edited the original post to remove that ambiguity.

Its sad to see that Beersmith has the same error. Want to guess where they got their information from?
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Re: Palmer Spreadsheet Error

Wed Dec 15, 2010 6:49 am

Palmer is assuming you put the chalk in the mash, not dissolve it in water.

As Kai mentioned on the AHA forum, whether by design or happy accident that works out pretty well as chalk in the mash appears to affect mash pH about half as much as it should (half as much as if it were dissolved in the mash liquor).

This issue, and the most sophisticated (and most likely to be close to accurate) SRM -> RA model I've seen published have been handled in Kai's water spreadsheet for a year or two at least.
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