Author Topic: BeerSmith IBU calcs through the roof "help"  (Read 10015 times)

Offline Flux

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BeerSmith IBU calcs through the roof "help"
« on: April 19, 2012, 09:19:45 AM »
Hi little problem Basically just been trying to run a coopers pale ale recipe to 23L simple enough , using the Australian Pale Ale Extract (Coopers) with these figures, Weight - 1.7kg, Colour - 90EBC, Bitterness - 340IBU
But when I add all the ingredients to BeerSmith, the can IBU value of 340 IBU gal/Ib doesn't dilute the finished product in "Style Guide Comparison" (the green slider scales for altering recipe values).Thus showing a finished beer bitterness of 187.4IBU's , and I'm like what the? I want a value of 35IBU's.
I hope that is clear to you guys but can anyone tell me what I am doing wrong here please, as I just can't get it? I know the 340IBU original value is for the 1.7kg extract can but why hasn't it diluted to match the batch volume?
Can I remove the hopped extract figure and just leave it blank as then everything seems to work as normal, confused?

Thanks in advance.
« Last Edit: April 19, 2012, 09:26:42 AM by Flux »

Offline Flux

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Re: BeerSmith IBU calcs through the roof "help"
« Reply #1 on: April 21, 2012, 12:14:36 AM »
Ok found the problem As the kit is sold in Kg's as opposed to litres it makes it a weight to volume dilution. You need to multiply the stated IBU by the weight of the tin (in KG) then divide by your final volume (in Litres).

So for a 23 litre brew: (340 X 1.7)/23 = 25 IBU

But still I would have assumed that BeerSmith would have calculated this figure in the brewing script calcs itself rather than doing it yourself.
In my mind this is an under sight and fault on the programs part, as the value you get when you enter the ingredient  is 340 IBU/lb and it doesn't change when you enter your batch volume which it should.

Offline BeerSmith

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Re: BeerSmith IBU calcs through the roof "help"
« Reply #2 on: April 22, 2012, 03:01:17 PM »
Hi,
  The IBU/Gal lb is the number of IBUs in one pound of extract dissolved into one gallon of wort.  It seems unlikely that one pound of extract would contain 340 IBUs if dissolved into one gallon of wort.  Are you sure you have this right?

  The way the calculation is done can be illustrated by this example:
    - Pretend I have 1 lb of Pale liquid extract that has 50 IBU-gal/lb
    - If I add this 1 lb into a 1 gallon recipe, I get 50 IBUs
    - If I added this 1 lb to a 5 gallon recipe I get 20 IBUs

  So the calculation BeerSmith is doing is very simple.  It takes the number you provide (IBUs-gallons/lb) and multiplies it by the number of pounds of extract you have added, then divides by the number of gallons in the recipe to get the IBU value for the recipe.

  You can do the same in metric - it does not change the relationship.

Brad
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Offline xtian

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Re: BeerSmith IBU calcs through the roof "help"
« Reply #3 on: August 08, 2012, 09:32:32 AM »
The problem is the same for all the Coopers products in the Coopers Add-in ... both for IBU and EBC. The IBU and EBC are correct as stated on the Coopers website but are wildly different from the numbers against similar products in BeerSmith. For instance, the default Amber Liquid Extract has EBC=24.6 whereas the Amber Malt Extract (Coopers) has EBC=340.0.

My assumption would therefore be that the numbers provided by Coopers are somehow calculated differently from those against similar products. Is it obvious how?

This is killing me as given my reliance on Coopers products I have as yet been unable to get any value from BeerSmith.

Cheers.

Offline xtian

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Re: BeerSmith IBU calcs through the roof "help"
« Reply #4 on: August 25, 2012, 03:26:31 AM »
OK, I'm going out on a limb here. I'm useless with numbers but given say the IBU value stated on the Coopers website (and in the Coopers Beersmith add-in) for the Thomas Coopers Irish Stout is 560.0 and the kit is intended to brew 23L, I have simply divided the IBU by 23 to get 24.3IBU ... which seems within BJCP guidelines for Sweet Stout and close to the low end for some of the other stouts.

For those also struggling with a similar problem for the EBC of Coopers products (see http://www.beersmith.com/forum/index.php/topic,6897.msg29578.html#msg29578) the same workaround seems to apply.

Would appreciate any confirmation or criticism of this approach.

Cheers.

Offline tom_hampton

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Re: BeerSmith IBU calcs through the roof "help"
« Reply #5 on: August 25, 2012, 01:06:08 PM »
Hi,
  The IBU/Gal lb is the number of IBUs in one pound of extract dissolved into one gallon of wort.  It seems unlikely that one pound of extract would contain 340 IBUs if dissolved into one gallon of wort.  Are you sure you have this right?

  The way the calculation is done can be illustrated by this example:
    - Pretend I have 1 lb of Pale liquid extract that has 50 IBU-gal/lb
    - If I add this 1 lb into a 1 gallon recipe, I get 50 IBUs
    - If I added this 1 lb to a 5 gallon recipe I get 20 IBUs

  So the calculation BeerSmith is doing is very simple.  It takes the number you provide (IBUs-gallons/lb) and multiplies it by the number of pounds of extract you have added, then divides by the number of gallons in the recipe to get the IBU value for the recipe.

  You can do the same in metric - it does not change the relationship.

Brad

Brad, where did you get this unit from? I can't find a single maltster that specifies thier products this way? The coopers kit referenced here directly specifies the ibu of the extract. 
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Offline tom_hampton

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Re: BeerSmith IBU calcs through the roof "help"
« Reply #6 on: August 26, 2012, 03:09:08 AM »
Flux-

You can do the same calculation that you did to get the right IBU-gal/lb number:

(340 * 1.7) / 3.78 = 152

Then divide by 3.75 lbs = 41 IBU-gal/lbs

41 * 3.75 / 6 gallons = 26 IBUs

To do the conversion from IBUs to IBU-gal/lb faster:

IBUS * (1.7/3.78/3.75) = IBUs * 0.12


Given that I can't find any maltster out there that uses this unit, it seems silly to expect you to figure it...but, you can't change beersmith.  So, at least this way you should be able to get it to do what you want.
R.I.P.:Belgian Blonde
On Tap: Apfelwein, Kolsch(v2), Pumpkin Ale, Belgian Specialty 
Aging/Storing: Coffee Porter, Chocolate Porter, Flanders Red, English Barlywine
Fermenting: Maggie's Altbier
Next Up: PtE(1.1), Belgian Dubbel?

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Offline Brewsta

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Re: BeerSmith IBU calcs through the roof "help"
« Reply #7 on: April 20, 2014, 06:24:07 PM »
Tom,
i have been plagued by this problem and appreciate your comments on how to get the correct IBU's, call me dumb as i am not that good with maths, but which value do i enter in the IBU gal/lb field? 26 IBU's or IBUS * (1.7/3.78/3.75) = IBUs * 0.12 which = 4.89?

also i took the time to enter the example Brad gave into BS2 and i did not get the same result? i.e.

1lb / 1gal = 50 ibu i  get 33.3 ibu's?

1lb / 5 gal = 20 ibu i get 9.1 ibu's?

this is really doing my head in as i have already put down 3x brews using BS2 and all three are too bitter…
many thanks!

 

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