Home Brew Forums > Extract ppg question

08-19-2012, 12:05 AM   #1
Nil
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 Extract ppg question

I was performing some density calculation in order to double check the claimed number of points per gallon for an extract.

If one pound = 454.5 grams and one gallon = 3758 grams (at room temperature), I would expect that, once the extract is added to the water, the total weight would become 454.5 + 3758 = 4212.5 grams.

Now, if I divided 4212.5 grams/3758 mL, I would get an extract concentration of 0.121 g/mL or a density of 1.121 that three times the density reported on the books (0.04 g/mL or 1.040).

If I multiply 0.121 X 3785 I get 454.7 grams = one pound. If I do the same for 0.04 X 3785 I get 151.4 g or 0.3 pounds.

I did the experiment, by dispersing one pound of DME in one gallon of water and got a density close of 1.040.

I was thinking that, this is a matter of water buoyancy (?). The same way that you (and I) weight less inside a pool full of water, maybe the dissolved molecules weights less in water.

Please let know if I am missing something.

Thanks!, Nil

08-19-2012, 01:55 AM   #2
Calder
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Way too complicated after a few beers.

I tried to follow it, but when I found you used both grams and mL for the same number, I decided it was way too much effort to sort through it. ..... Question: Does 1 mL of water = 1 gram?

I use 36 points for LME, 45 for DME and 46 for table sugar in recipes. When I check the gravity of the wort, I find I am generally within .001 of the calculated gravity. That is good enough for me.

08-19-2012, 03:42 AM   #3
Nil
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Calder,

The density of water is 1g/ 1mL at room temperature.

I used 40 ppg's for DME as per John Palmer's book and my personal experience. Where did you got 45 ppg's from?

Thanks, Nil

08-19-2012, 04:07 PM   #4
Calder
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I've used 45 points for the longest time, but not really sure where I got it from. Just doing a quick check of a couple of sources I found:

Checking the Breiss data sheet for it's Pilsner DME, it says 1.34 lbs in a gallon = 1.060.

1/1.34 = 44.8 points per lb.

Checking BeerSmith database it lists all dry extracts as 44 points per lb.

Papazian 'Home Brewers Companion' says it varies, up to 45 points per lb.

08-20-2012, 09:54 PM   #5
hector
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1 lb = 453.6 grams

1 gallon of water weighs 3.78 Kg

You should NOT add one pound of extract to one gallon of water .

In fact , you should make a solution . That means , you should dissolve one pound of extract in 1/2 gallon of water and then dilute it to

one gallon by topping up .

I dissolved once 120 grams of DME in 0.5 liter of water and topped up to 1 liter . My Hydrometer read 1.046 .

Hector