Bug?
Posted: Tue Sep 08, 2009 6:27 pm
I realize that Jeff is probably sick and tired of my nit-picking and a few 'false alarms', but I've discovered something in BTP that mystifies me.
I was trying to use BTP to determine the gravity of a sugar-water solution for the purpose of furthering a discussion in another forum regarding the change in volume of water as sugar is added. I came upon a source which indicates that the total volume of a 20% sucrose-water solution is actually less than the volume of the water before the sucrose is added, For anyone interested, here is the link: http://www.madsci.org/posts/archives/19 ... .Ch.r.html
Anyway, I started with a blank recipe, set the final volume to 8 liters at 68F (which IIRC should be close enough to count as 8,000 grams of water) and added as my only ingredient 2kg of sucrose, thus making a 20% solution. There are NO other ingredients; although it appears unnecessary to do so, I set my efficiency to 100%, and also my attenuation to 100%. Now here are the problems, looking under the 'Analysis' tab:
The O.G. indicates 1.095 which I presume is correct, while the T.G. (terminal gravity indicates 1.000 which is the gravity of pure water. But with the alcohol added (which has a gravity of less than 1.000), then the resulting T.G. should be less than one ... shouldn't it? The tab also shows the presence of 'carbs', but there shouldn't be any with 100% attenuation, correct?
Maybe this has to do with the 'real' versus 'apparent' attenuation. I then tricked BTP by raising my attenuation setting to 122% which causes the data under the 'Analysis' tab to show a T.G. of 0.979 and a real attenuation of 100%. What is confusing to me is that if it is doing it with this, then when I enter a value in my attenuation field based on the information about a particular variety of yeast (I usually use the middle of any range that is given), how do I know that the data under the tab is correct until I enter an actual final gravity reading when fermentation is complete?
It just seems strange to need to put a value exceeding 100% in any field.
Cheers.
Bill Velek
I was trying to use BTP to determine the gravity of a sugar-water solution for the purpose of furthering a discussion in another forum regarding the change in volume of water as sugar is added. I came upon a source which indicates that the total volume of a 20% sucrose-water solution is actually less than the volume of the water before the sucrose is added, For anyone interested, here is the link: http://www.madsci.org/posts/archives/19 ... .Ch.r.html
Anyway, I started with a blank recipe, set the final volume to 8 liters at 68F (which IIRC should be close enough to count as 8,000 grams of water) and added as my only ingredient 2kg of sucrose, thus making a 20% solution. There are NO other ingredients; although it appears unnecessary to do so, I set my efficiency to 100%, and also my attenuation to 100%. Now here are the problems, looking under the 'Analysis' tab:
The O.G. indicates 1.095 which I presume is correct, while the T.G. (terminal gravity indicates 1.000 which is the gravity of pure water. But with the alcohol added (which has a gravity of less than 1.000), then the resulting T.G. should be less than one ... shouldn't it? The tab also shows the presence of 'carbs', but there shouldn't be any with 100% attenuation, correct?
Maybe this has to do with the 'real' versus 'apparent' attenuation. I then tricked BTP by raising my attenuation setting to 122% which causes the data under the 'Analysis' tab to show a T.G. of 0.979 and a real attenuation of 100%. What is confusing to me is that if it is doing it with this, then when I enter a value in my attenuation field based on the information about a particular variety of yeast (I usually use the middle of any range that is given), how do I know that the data under the tab is correct until I enter an actual final gravity reading when fermentation is complete?
It just seems strange to need to put a value exceeding 100% in any field.
Cheers.
Bill Velek