plato X balling

[LuizArgh]

So, here's the thing: I'm in a personal crisis here.

All my life, while using conversion tables, I thought that "g/100g" was the same as ºPlato, while "g/100ml" was another way of saying ºBalling. But recently, while looking deeper on the subject as a matter of personal curiosity, I have seem people stating either that:

1) it's actually the other way around (1ºP=1g/100ml and 1ºB=1g/100g)

OR:

2) both are a measurement of weight (g/100g) although with a slight difference on the way the scales were originally conceived

OR:

3) you should just drop this nonsense and go back to the good old Specific Gravity Points

so: which of the 4 statements is right?
(I have been using both units for all my beer calculations and this is truly driving me insane....)

 

[LuizArgh]

ps: and no, wikipedia does NOT help.

 

[ajdelange]

#2 is correct but it is not a difference in the way the scales are conceived but rather the way in which the specific gravities of the sucrose solutions on which the scales are based were measured.

There was a pretty thorough discussion in Wikipedia but some genius decided to trash it and did and I'll be damned if I'll redo it only to have the same thing happen again. I also did a companion piece on Brix which has not been fiddled with and some of the material there applies to the Plato scale as well. The Wikipedia article on Specific Gravity has lots of brewing related references. It too has been 'improved' but is for the most part correct.

 

[Kaiser]

for all intents and purposes in brewing you can assume that Plato == Balling.

Don't go back to sg simply because you are confused by Plato vs. Balling. This wold not eliminate the problem anyway since sg based calculations also rely on the Plato scale under the hood.

A.J. has done some good work on this and is sure to chime in on this.

EDIT: looks like he already did

Kai

 

[LuizArgh]

Good, so I don't have to redo (most of) my work. But in that case, what about the g/100ml? There are several cases in which this is necessary (i.e. efficiency calculations) but I never found a formula to convert it back and forth from g/100g - everytime I need it I have to open my Goldiner/ Klemann "Stammwürze Korrectionstafel", which is not very practical...

also: after which value the difference in measurement between Plato and Balling becomes significant?

 

[ajdelange]

Good, so I don't have to redo (most of) my work. But in that case, what about the g/100ml?

To get that you need SG and degrees plato. The steps are
1. Convert SG to degrees Plato. That gives you grams_extract/100 grams_beer
2. Convert SG to density. That's grams_beer/ml_beer
3. Multiply 1 and 2. That gives grams_extract/100 ml_beer.

There are several cases in which this is necessary (i.e. efficiency calculations) but I never found a formula to convert it back and forth from g/100g - everytime I need it I have to open my Goldiner/ Klemann "Stammwürze Korrectionstafel", which is not very practical...

You can find all the details of the math at http://wetnewf.org/pdfs/Brewing_articles/Sugar_Gravity.pdf. There are several ways to tackle the problem. Probably the easiest is to set up a spreadsheet which calculates °P from SG (using the ASBC or extended polynomial) and multiplies this by SG and 0.998203 to give grams/100 mL as a function of SG. To convert back insert trial values into that formula until the calculated result matches the desired grams/100 mL. This process can be automated with Excel' Solver.

also: after which value the difference in measurement between Plato and Balling becomes significant?

Discrepancies are said to be in the fifth and 6th decimal places. Range is up to 1.08 and there are polynomials which go higher.

 

[LuizArgh]

now THAT'S what I call a reply with style. thanks a lot for the pdf!

I have been using De Clerck's formula to switch from ºP to SG, which in turn I use in Balling's formula to calculate ABW%. I actually made a very neat excel spreadsheet with these and a bunch of others, with the objective of having an "customize-it-yourself-open-source" sort-of brew software. I'm using currently the version 0.6 in my brewery with relative sucess there is a whole bunch of other stuff I would like to add (like a better carbonation and oxygenation calculator) but there is a lot of deep research involved, and as you might have guessed, my original diploma is not neither in science nor engineering fields...

also: don't give up so quickly on your page on wikipedia... just have a backup if hell breakes loose again.

cheers!