Calculating SRM of Parti-Gyle - Home Brew Forums

 Home Brew Forums > Calculating SRM of Parti-Gyle

09-05-2011, 06:05 PM   #1
DrJerryrigger
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So I have a hard time reading math typed out, so I just took pics of my chalk board.
I'm not sure if I'm doing these calculations right. I made the assumption that color extraction was proportional to sugar extraction. That's color in MCU's, not SRM.

09-06-2011, 06:01 PM   #2
DrJerryrigger
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Well, I guess I'll just brew it and see if these numbers look right....

09-06-2011, 08:16 PM   #3
hopsalot

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I believe your assumption is wrong.

MCU =(lovibond of grain * Grain weight)/ volume of batch

The volume used in the equation should be you batch/final volume.

22.8 SRM just from 1.8*L 2-row is way off, 4.37 SRM for 16 lbs at 1.8*L

I get 21.27 SRM for the batch

09-06-2011, 08:39 PM   #4
michaeltrego
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By my calcs in Promash, with that grainbill for a total of 9.2 gallons, the total SRM would be 15.9 -- let's say 16. According to the Mosher partigyle guidelines, when you do a 1/3 - 2/3 split of that 16 SRM, it would result in 24 SRM for the 1.078 big beer and 12 SRM for the 1.039 small beer (at 75% efficiency).

09-06-2011, 08:56 PM   #5
DrJerryrigger
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Quote:
 Originally Posted by hopsalot I believe your assumption is wrong. MCU =(lovibond of grain * Grain weight)/ volume of batch your SRM equation is right, but you miscalculated your MCU The volume used in the equation should be you batch/final volume. 22.8 SRM just from 1.8*L 2-row is way off, 4.37 SRM for 16 lbs at 1.8*L I get 21.27 SRM for the batch
Is the 22.8 your referring to on the bottom left of figure #1? If so that is the MCU from that grain before being divided by any volume.

Is that 21.27SRM for the both the 3.2gal and 6 gal batch combined?

09-06-2011, 09:18 PM   #6
DrJerryrigger
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Quote:
 Originally Posted by michaeltrego By my calcs in Promash, with that grainbill for a total of 9.2 gallons, the total SRM would be 15.9 -- let's say 16. According to the Mosher partigyle guidelines, when you do a 1/3 - 2/3 split of that 16 SRM, it would result in 24 SRM for the 1.078 big beer and 12 SRM for the 1.039 small beer (at 75% efficiency).
Cool thanks. Those number don't seem that far off from what I came up with (and off in the right way as it's not exactly the same).
That spread sheet looks quite useful, I'll try figure out what formula they used for it. But not right now, as I'm in the middle of a bottling operation.

09-06-2011, 09:30 PM   #7
hopsalot

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so you your total volume is 9.2 gal?

I get 6.73 SRM for the 3.2gal batch

and 19.76 SRM fo the 6gal batch

I dont know if you still sum the MCU's then calculate the SRM like you would if it was one batch with the same volume, so I am going to step out of this one.
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09-06-2011, 10:41 PM   #8
DrJerryrigger
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Quote:
 Originally Posted by hopsalot I dont know if you still sum the MCU's then calculate the SRM like you would if it was one batch with the same volume, so I am going to step out of this one.
Well, I don't really know the right way to do this either, but thanks for trying. I'll be making this tomorrow, so I can see if the original calculations are about right (wish I had some way of testing, other than "eyeballing it").

09-07-2011, 01:04 PM   #9
hopsalot

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Quote:
 Originally Posted by DrJerryrigger Well, I don't really know the right way to do this either, but thanks for trying. I'll be making this tomorrow, so I can see if the original calculations are about right (wish I had some way of testing, other than "eyeballing it").
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09-07-2011, 04:59 PM   #10
DrJerryrigger
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Quote:
 Originally Posted by hopsalot Right on, post your results
will do! I'm mashing right now. I'm sure things will work out differently than predicted, but I'll go back and calculate with the volumes and SG that I end up with, to see how things work out.