Volume Question

[tnlandsailor]

I have a simple question that I'm trying to get answered without the benefit of me having to actually perform an experiment. The question is this:

If I have 3 gallons of water, then add 5 lbs of DME to it, what is the volume now? In other words, what is the liquid volume addition of a certain amount of DME?

 

[Veinman]

I don't do a lot of extract batches but I would think the starting point would be to determine the volume of the amount of extract you plan to use dry and add that to your volume of water to get a starting point. It likely won't be a perfect estimate because it may dissolve slightly differently but I'd imagine it would be pretty close.

So I'd measure out 1 cup of DME weigh it and then calculate the volume of 5lbs of DME, add this volume to your 3 gallons and I'd bet you'd be pretty close to the actual volume.

 

[tnlandsailor]

I've answered my own question.

According to ProMash, DME contributes 46 points per pound per gallon. That means in 3 gallons of 1.046 wort, there is the equivalent of 3 lbs of DME. Using the SG of 1.046, that wort weighs => 3 gallons x 8.345 lb/gallon (weight of water) x 1.046 = 26.19 lbs. Of that, 3 lbs is DME, so the weight of water is 26.19 - 3 or 23.19 lbs. 23.19 lbs of water x 1 gallon/8.345 lbs = 2.78 gallons. That means the 3 lbs of DME contributed 0.22 gallons, or 0.0733 gallons per pound of DME. 0.0733 gallons equals 9.38 fl oz.