This is a BIAB calculator which uses a Novel method to calculate your grainbill, which is independant of "Into Boil Efficiency", and works well with large beers, with or without sparging
It's very accurate.
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I've been working on a solution to a problem which affects all BIABers who are using BIAB calculators to determine their volumes and grain bills
I think I've cracked it
The problem is this, as you increase the gravity of the wort you are creating the effciency goes down. Most of us have experienced this and we know that we get about 83% Into Boil effciency for "normal" beers, and maybe 75% for bigger beers.
With my experiments in Maxi-BIAB it really rammed this home when you start getting 70% Into Boil and perhaps just 60% into the fermenter.
Anyway, the solution was to look at the concept of Conversion Efficiency, and then to create a calculator which uses Conversion Effciency to predict BIAB results, rather than Into Boil efficiency.
The new calculator uses just three values to control/predict the calculations, and these values do not vary (that's the theory at least) between brews and batch sizes.
1) Evaporation
2) Real Grain Absorption
3) Conversion Efficiency
update: it has become apparent that we only really need to know "Evaporation"!
if we know these, then we can predict brew volumes and gravities with high accuracy.
Your evaporation can be guestimated by the current BIAB calculators, and is easy to refine over 1 or 2 brews.
Real Grain Absorption is generally about 1 to 1.2L/KG, depending on if you squeeze or not. This is not the same as Apparent Absorption, but again, doesn't vary much, and is easy to calculate over a brew or two.
update: Real Grain Absorption should be about 1.41L/KG if you don't squeeze the bajeezus out of your bag. It will be more like 1.3L/KG if you do
Conversion Efficiency. Your conversion efficiency is how effectively you converted the grain starches into grain sugars in the mash. With BIAB it is fairly easy to get 95-100% of the laboratory extract results. A value of 95% should be reguarded as a good goal for most BIABers and if you are getting less than that, then you have probably got a problem in your mash.
update: most BIABbrewers with good techniques should be able to manage 99% efficiency. If not it means your grain is probably not milled correctly, or some other problem with your mash. This is assuming that the calculator is using the correct malt specs for your grain
With those three values, which we have good estimates for, we can predict with a high reliability the BIAB process and grain bill.
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That's the theory anyway
Now we need to test it
update: it works
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Current Version: viewtopic.php?f=74&t=1066&p=15537#p15537
A New Approach to BIAB Calculus using Conversion Efficiency
Post #1 made 12 years ago
Last edited by stux on 31 Oct 2011, 14:53, edited 13 times in total.
Fermenting: -
Cubed: -
Stirplate: -
On Tap: NS Summer Ale III (WY1272), Landlord III (WY1469), Fighter's 70/- II (WY1272), Roast Porter (WY1028), Cider, Soda
Next: Munich Helles III
5/7/12
Cubed: -
Stirplate: -
On Tap: NS Summer Ale III (WY1272), Landlord III (WY1469), Fighter's 70/- II (WY1272), Roast Porter (WY1028), Cider, Soda
Next: Munich Helles III
5/7/12