Need help with a calculation - Home Brew Forums

 Home Brew Forums > Need help with a calculation

06-03-2009, 05:18 PM   #1
Chips
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Feb 2009
Hamilton ON
Posts: 86

Well I've searched the forums far and wide but have had a hard time finding a calculator that will help me figure out my total mash volume.

Basically, I'd like to be able to enter the amount of water in my mash tun and the amount of grains. The calculator would then spit out the total volume.

It'd also be nice to know what volume would be left over after I remove the grains (using a BIAB system) but the first calculation is the most important.

Any links or formulas would be greatly appreciated!

06-03-2009, 05:19 PM   #2
PseudoChef

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Apr 2007
West Chicago 'Burbs, IL
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Here you go!

Green Bay Rackers--Mash Calculators

06-03-2009, 05:22 PM   #3
springer

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Feb 2008
Wappingers falls NY
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I use this one mash it
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06-03-2009, 06:12 PM   #4
MMW
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Apr 2009
Longview, TX
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Quote:
 Originally Posted by Chips Well I've searched the forums far and wide but have had a hard time finding a calculator that will help me figure out my total mash volume. Basically, I'd like to be able to enter the amount of water in my mash tun and the amount of grains. The calculator would then spit out the total volume. It'd also be nice to know what volume would be left over after I remove the grains (using a BIAB system) but the first calculation is the most important. Any links or formulas would be greatly appreciated!
I've been kicking around BiaB recently too, here's how I've been thinking it through (giving it a go this weekend, we'll see how it turns out):

For total volume, you need to figure grain absorption. According to the Aussies I've been reading that's 0.5-0.75 l/kg = 0.5-0.75 l/kg * (1.057 qt/l)*(0.453 kg/lb) = 0.5-0.75*0.48 qt/lb = 0.24-0.36 qt/lb grain absorption.

Now plug your grain weight into the calculator with a mash thickness in that range. This gives a grain + absorbed water volume.

That's the total volume in your mash.

For total water, figure the water for grain absorption then add the three items above.

From everything I've been reading, the only fixed quantity here is the batch size...everything else is based on experience in your system. Hope that helps, and if anybody notes any flaws with that I'm sure they won't hesitate to point them out

06-03-2009, 06:18 PM   #5
Zen_Brew

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May 2009
Seattle
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Most of the brewing softwares will figure that out for you as well. I downloaded the trial version of Beer Smith which seems pretty helpful and the trial version doesn't seem very restricted. Not a bad piece of software for the \$20 or so.
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06-03-2009, 08:10 PM   #6
Chips
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Feb 2009
Hamilton ON
Posts: 86

Alright...so I guess I'm just thinking out loud here, but correct me if you see an error:

I'd like my total post-boil volume to be 23L.
So pre boil will have to be 27L. Plus if I assume 3L lost to 5Kg of grain so my total pre-mash volume will be 30L.

30L water / 5 Kg grain = 6 L/Kg mash thickeness. Using that Green Bay "Can I Mash it" calculator I guess I'll need a pot at least 33L (mine is 40). Looks like it'll work!

Thanks to everyone for their input!

06-03-2009, 09:07 PM   #7
ajf
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Oct 2005
Long Island
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I'd like my total post-boil volume to be 23L.
So pre boil will have to be 27L.
That would be true if you boil off 4L and transfer everything from the kettle to the fermenter, or boil off xL, and leave (4 - x)L in the kettle. 4L seems to be a reasonable amount.

Plus if I assume 3L lost to 5Kg of grain so my total pre-mash volume will be 30L.
I would guesstimate that you would lose 5.2L to grain absorbtion.

30L water / 5 Kg grain = 6 L/Kg mash thickeness.
You don't want to use 6L/Kg for the mash. You need about 2.5 - 5 L/Kg (2.5 is thick, 5 is thin) for the mash, and you need to use the remaining water for sparging. If you mash too thin, you may not get full conversion.

Using that Green Bay "Can I Mash it" calculator I guess I'll need a pot at least 33L (mine is 40). Looks like it'll work!
Yup.

-a.
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06-04-2009, 04:53 PM   #8
Chips
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Feb 2009
Hamilton ON
Posts: 86

Plus if I assume 3L lost to 5Kg of grain so my total pre-mash volume will be 30L.
I would guesstimate that you would lose 5.2L to grain absorbtion.

30L water / 5 Kg grain = 6 L/Kg mash thickeness.
You don't want to use 6L/Kg for the mash. You need about 2.5 - 5 L/Kg (2.5 is thick, 5 is thin) for the mash, and you need to use the remaining water for sparging. If you mash too thin, you may not get full conversion.
[/QUOTE]

Alright since I've never done a full boil before I'll go with 4 L lost to an hour long boil, and 5.2L loss to grain absorption. I think everything should still fit!

I'm going to do a "Brew in a Bag" or BiaB method so while the mash seems ultra thin (and it is) everything apparently works out just fine. Here's an informative post about brewing in a bag:
BIAB

Thanks again for the great feedback!