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 Home Brew Forums > Partigyle Gravity Calcs?
08-10-2012, 09:37 PM   #1
bikesnbeers
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 Partigyle Gravity Calcs?

Hi all,

I'm trying to formulate a partigyle batch for this weekend. I'm planning on making a double IPA and a Pale. I've never done a partigyle, so I consulted the web to try to find out how to do the calcs, but have come up with some conflicting info (I think).

I plan to batch sparge 50/50. I want the double to come in around 1.070.

According to (2) and (4) below, I want to start with a recipe that would give me 1.060.

According to (3) below, I want to start with 1.0530. (1) basically agrees with (3).

So, which one is it? Thanks!

(1)
"Roughly speaking, the second batch will have half the gravity of the first batch. "
http://www.homebrewtalk.com/wiki/index.php/Parti-gyle

(2)
Batches split into two equal volumes have a different ratio: ~58% of the extract will be in the first half of the runoff and ~42% in the second half. For example, a 15-gal master batch designed to produce 16 °P wort contains 240 °gals (15 X 16 = 240). The first half will be 18.56 °P (240 X 0.58/7.5 =18.56); the second half will be 13.44 °P (240 X 0.42/7.5 = 13.44).

(3)
1.060 total -- 1.080 (first half), 1.040 (second half)

(4)
For a 50-50 split by volume, with half of the wort in each batch we get a roughly 58% of the gravity points in the first batch. So a 1.060 overall batch OG would translate to a 1.070 first runnings and 1.050 second runnings, with both of equal size.
http://beersmith.com/blog/2011/10/07...from-one-mash/

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08-11-2012, 05:15 AM   #2
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I hope someone can add some commentary about their experience(s) because I have the exact same type of questions as I prepare for my first partigyle!

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08-12-2012, 12:21 PM   #3
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I've partigyled twice (barley wine/ special bitter). My experience is that roughly 2/3rds of your gravity will come during the first runnings. I fly sparge however, and am not sure if this holds true for batch sparge.
I calculate for 80% efficiency total, and the first runnings yeild 55% eff, while second runnings are 25%. In my case I used 23lbs grain and barley wine grav (post boil from 7 gal collected) was 1.090. The bitter came in at 1.042 (post boil from 6 gal collected). Hope that helps....

Oh...and I suggest steeping additional grains or adding a bit of extract for the second runnings. They tend to be a bit thin in flavor since the bulk of character is in the 1st runnings.

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08-12-2012, 12:26 PM   #4
phenry
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I would suggest running off more wort for the first gyle than you actually need in case your second runnings end up way low... I did my first parti-gyle on Friday and ended up with a huge disparity between the gravity of my two batches. Something along the lines of 1.088 and 1.024 with a 1/3-2/3 split. Not sure how I got such good efficiency with my first runoff, but I ended up having to do a bit of blending the two batches before boiling to come closer to my desired gravities.

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08-13-2012, 03:26 AM   #5
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I would check out Kai Troester's website, especially this and this for additional reading. If you've taken good notes and measurements of your previous brews, you are already half way there!

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08-13-2012, 02:15 PM   #6
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Quote:
 I would check out Kai Troester's website, especially this and this for additional reading. If you've taken good notes and measurements of your previous brews, you are already half way there!
I came across Kai's site after I posted. I then spent most of Sat. reading it and messing with spreadsheets instead of brewing like I planned. There is a TON of great info on that site. I ended up doing a partigyle yesterday. The numbers were pretty close to his Batch Sparge and Party Gyle Simulator spreadsheet. I need to dial in the conversion efficiency. Mine is no where near 100%. Thanks!
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08-13-2012, 02:39 PM   #7
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Good stuff. My conversion efficiency is somewhere between 85-90% so that's where my losses are. It was interesting to see that go down from a hand-cranked corona mill to a motorized mill I used at a well-known homebrew supplier. I have to double-crush the grains there to get the same level of efficiency as before. But yeah, best of luck with the new batches!

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08-15-2012, 04:21 AM   #8
bikesnbeers
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I've been finding that my conversion efficiency in the batch sparge simulator (BSS) is something that I haven't been able to adjust in Beersmith (BS). The mash efficiency in BS is calculated for you, and BS doesn't take into account factors like the crush or pH. My mash efficiency in BS is 70%, but my conversion efficiency in the BSS is 79%. I'm not checking pH and my grain is milled at the LHBS, so I expect the BSS conversion to be less than 100%. I think the BSS is more accurate. Does that sound right to you?

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