Author Topic: metric nerdery please: calculation question  (Read 4348 times)

Offline Thirsty_Monk

  • Brewmaster General
  • *******
  • Posts: 2133
  • Eau Claire WI
    • View Profile
Re: metric nerdery please: calculation question
« Reply #15 on: March 22, 2012, 04:56:26 PM »
okay, after further research I don't like my beer any colder than 280 degrees kelvin

After still further research you will learn that that isn't a unit of measurement. ;)
And now I am out of this conversation.
Even thou I am more then fluent in mertic I measure:
grain in lb,
hops in grams,
temp in F
gravity in Plato
volume in gallons.

Boy I am screwed up.
Na Zdravie

On Tap At The TapRoom:
Bohemian Pilsner
Bohemian Dark Lager
Smoked Bock
MaiBock
American Brown Ale
Marzen
Root beer

Offline punatic

  • Official Poobah of No Life.
  • *
  • Posts: 4583
  • Puna District, Hawaii Island (UTC -10)
    • View Profile
Re: metric nerdery please: calculation question
« Reply #16 on: March 22, 2012, 05:33:11 PM »
okay, after further research I don't like my beer any colder than 280 degrees kelvin

After still further research you will learn that that isn't a unit of measurement. ;)
And now I am out of this conversation.
Even thou I am more then fluent in mertic I measure:
grain in lb,
hops in grams,
temp in F
gravity in Plato
volume in gallons.

Boy I am screwed up.

Hey, if it works don't fix it.   8)

I like specific gravity because it is unitless.

Kelvin is an absolute scale so its units are not expressed in degrees.
There is only one success: to be able to spend your life in your own way.


AHA Life Member #33907

Offline malzig

  • Brewer
  • ****
  • Posts: 466
    • View Profile
Re: metric nerdery please: calculation question
« Reply #17 on: March 22, 2012, 05:55:28 PM »
The imperial system makes so little sense to me, I do all my measurements in metric. I couldn't tell you how many ounces are in 3 pints if my life depended on it.
48
Don't you mean 60?  ;)

Offline gmac

  • Brewmaster General
  • *******
  • Posts: 2108
  • London, Ontario
    • View Profile
Re: metric nerdery please: calculation question
« Reply #18 on: March 22, 2012, 06:25:58 PM »
8 ounces in a cup right?
2 cups in a pint right?
2 pints in a quart right?
3 pints would be.... the start of a good evening....

Base 10 system is way better.
« Last Edit: March 22, 2012, 06:28:01 PM by gmac »

Offline chezteth

  • Brewer
  • ****
  • Posts: 417
    • View Profile
Re: metric nerdery please: calculation question
« Reply #19 on: March 22, 2012, 06:45:00 PM »
I started using metric when I realized that, on my system, at 75% brewhouse efficiency and brewing a 6 gallon batch ( approx 23L ). I could just use the last 3 digits of the OG to calculate how many kg of grain I needed for a batch.  e.g. 1.050 OG would require 5.0kg of grain  I still use degrees F for temp but I am also switched over to liters for volume.  The metric system makes things so much easier.   :D

Offline dcbc

  • Brewer
  • ****
  • Posts: 277
    • View Profile
Re: metric nerdery please: calculation question
« Reply #20 on: March 22, 2012, 07:32:44 PM »
okay, after further research I don't like my beer any colder than 280 degrees kelvin

After still further research you will learn that that isn't a unit of measurement. ;)
And now I am out of this conversation.
Even thou I am more then fluent in mertic I measure:
grain in lb,
hops in grams,
temp in F
gravity in Plato
volume in gallons.

Boy I am screwed up.

Exactly what I do.  Screwy loves company.
I've consumed all of my home brew and still can't relax!  Now what!

Offline morticaixavier

  • Official Poobah of No Life.
  • *
  • Posts: 7107
  • Davis, CA
    • View Profile
    • The Best Artist in the WORLD!!!!!
Re: metric nerdery please: calculation question
« Reply #21 on: March 22, 2012, 09:57:56 PM »

Kelvin is an absolute scale so its units are not expressed in degrees.

well then.. after correction from more knowledgable folks I don't like my beer any colder than 280 K

Offline pikelakehomebrew

  • Cellarman
  • **
  • Posts: 47
  • brewing in the north metro
    • View Profile
    • Pike Lake Home Brew
Re: metric nerdery please: calculation question
« Reply #22 on: March 23, 2012, 06:50:15 AM »
The formula is actually the same, it's just the constants and units that change. So instead of representing potential extract as, say, point-gallons per pound, you'd use degree Plato-liters per kilogram, and so on. Base malts tend to be around 37 point-gal/lb, which is about 77 °P-L/kg. If you want to brew 20 L of a 12°P (1.048) beer at 80% efficiency:

(20 L * 12°P)/(77°P-L/kg * 80%) = 3.9 kg

or in American customary units: (5.25 gal * 48 points)/(37 point-gal/lb * 80%) = 8.5 lb

The two answers are the same, just given in different units.

°Plato tends to be more common in Europe, SG in the UK, and American brewers use whichever they learned first, more or less.

Thanks Sean.  That's what I was wondering about — Plato being the generally "non-American" standard measurement for Gravity.  I didn't think that you'd mix G.U.'s with Metric measurements, so that makes sense.

How closely does Plato and Brix run?  Is there a formula for conversion from Brix to Plato, or are they pretty much the same?
pikelakehomebrew.com
On tap: Oktoberfest, Belgian Dubbel, Peach Blonde Ale, Surly Furious clone

Offline a10t2

  • Official Poobah of No Life.
  • *
  • Posts: 3488
  • Ask me why I don't like Chico!
    • View Profile
    • SeanTerrill.com
Re: metric nerdery please: calculation question
« Reply #23 on: March 23, 2012, 08:19:17 AM »
How closely does Plato and Brix run?  Is there a formula for conversion from Brix to Plato, or are they pretty much the same?

They're the same out to the second or third decimal place, so for brewing purposes you can just treat them as identical.

If you're encountering °Brix because of a refractometer, though, there are corrections that need to be made. They have to do with the properties of wort, rather than the actual measurement units. http://seanterrill.com/2010/06/11/refractometer-estimates-of-final-gravity/
Beer is like porn. You can buy it, but it's more fun to make your own.
seanterrill.com/category/brewing
twomilebrewing.com

Offline pikelakehomebrew

  • Cellarman
  • **
  • Posts: 47
  • brewing in the north metro
    • View Profile
    • Pike Lake Home Brew
Re: metric nerdery please: calculation question
« Reply #24 on: March 23, 2012, 03:40:43 PM »
If you're encountering °Brix because of a refractometer, though, there are corrections that need to be made. They have to do with the properties of wort, rather than the actual measurement units. http://seanterrill.com/2010/06/11/refractometer-estimates-of-final-gravity/

So °Brix from a refractometer is really a misnomer, at least not truly °Brix without dividing the reading by 1.04?  /shrug  All this time I had been hearing from others and assuming that the refractometer was a Brix reading.  Score one more for the online information correction team.

A couple questions about both of those massive formulas — pardon my lack of scientific understanding; I'm a web designer and developer, not a scientist.

I see notations of RIi1, RIi2, RIi3 and the same pattern for RIf.  I understand that RI is the refractive index and that i and f are initial and final respectively.  But what is the numeric value in that?  I didn't quite follow if you were taking three RI readings at the beginning and end, or if that meant something else.

The other item I didn't quite follow in your larger formula is where it says 0.0216*LN.  What does LN correlate to?  I didn't see any indication as to what that stood for.


Your formula is very impressive, and I can't imagine how long it take to come up with that.  Your nerdery is certainly exponentially higher than I could hope to attain.  Cheers to you, my friend!

With thieving out fermenting wort to take measurements and losing volume as a big concern for a number of home brewers, you'd think that someone would have come up with a hydrometer that required less volume for measurement by now. 
pikelakehomebrew.com
On tap: Oktoberfest, Belgian Dubbel, Peach Blonde Ale, Surly Furious clone

Offline a10t2

  • Official Poobah of No Life.
  • *
  • Posts: 3488
  • Ask me why I don't like Chico!
    • View Profile
    • SeanTerrill.com
Re: metric nerdery please: calculation question
« Reply #25 on: March 23, 2012, 04:00:46 PM »
So °Brix from a refractometer is really a misnomer, at least not truly °Brix without dividing the reading by 1.04?

Not exactly. A degree Brix (or Plato) is equivalent to 1% of the solution (by weight) being sucrose. So if you have 1 kg of a 15°Bx sucrose solution, you have 150 g of sucrose and 850 g of water.

A refractometer doesn't measure the density of the solution, though. It measures the refractive index. Since the RI changes with changing sucrose concentration, you can calibrate a refractometer such that it will give a reading in °Bx instead of RI, saving you some time and effort in converting. Which is all well and good if you're making wine, since the sugars in grape must are almost entirely sucrose.

Beer wort is a mixture of a dozen or so sugars, and sucrose isn't even the most common (maltose is). So to use a refractometer to measure the density of wort, you have to use a different conversion from RI to density.

I see notations of RIi1, RIi2, RIi3 ... But what is the numeric value in that?

The superscript is simply the exponential notation. x2 is "x to the second power", x3 is "x to the third power", etc.

The other item I didn't quite follow in your larger formula is where it says 0.0216*LN.

"ln" is the natural logarithm, a logarithm with e as the base. (e is a non-rational number equal to about 2.718.) http://en.wikipedia.org/wiki/Natural_logarithm

Truly, the ridiculously lengthy formula is just there for comic effect. If you actually want to convert refractometer readings either download the spreadsheet or use the online calculator.
Beer is like porn. You can buy it, but it's more fun to make your own.
seanterrill.com/category/brewing
twomilebrewing.com

Offline brewmonk

  • Assistant Brewer
  • ***
  • Posts: 117
  • Norcia, Italy
    • View Profile
    • Birra Nursia
Re: metric nerdery please: calculation question
« Reply #26 on: April 02, 2012, 06:10:08 AM »
The easiest way to add fun to your brewday is to do calculations in hexadecimal  ;)
Br. Francis
Birra Nursia

Offline Thirsty_Monk

  • Brewmaster General
  • *******
  • Posts: 2133
  • Eau Claire WI
    • View Profile
Re: metric nerdery please: calculation question
« Reply #27 on: April 03, 2012, 07:03:09 PM »
The easiest way to add fun to your brewday is to do calculations in hexadecimal  ;)
Funny.
Na Zdravie

On Tap At The TapRoom:
Bohemian Pilsner
Bohemian Dark Lager
Smoked Bock
MaiBock
American Brown Ale
Marzen
Root beer

Offline morticaixavier

  • Official Poobah of No Life.
  • *
  • Posts: 7107
  • Davis, CA
    • View Profile
    • The Best Artist in the WORLD!!!!!
Re: metric nerdery please: calculation question
« Reply #28 on: April 03, 2012, 09:56:23 PM »
The easiest way to add fun to your brewday is to do calculations in hexadecimal  ;)

my last brew clocked in at 01 2a. I expected better but I only got 3f percent efficiency. Ahh well it's only 0a gallons and it's still good.

Offline a10t2

  • Official Poobah of No Life.
  • *
  • Posts: 3488
  • Ask me why I don't like Chico!
    • View Profile
    • SeanTerrill.com
Re: metric nerdery please: calculation question
« Reply #29 on: April 04, 2012, 09:11:35 AM »
my last brew clocked in at 01 2a. I expected better but I only got 3f percent efficiency. Ahh well it's only 0a gallons and it's still good.

I'll play. 1.042, 63% efficiency, 10 gal?
Beer is like porn. You can buy it, but it's more fun to make your own.
seanterrill.com/category/brewing
twomilebrewing.com