### Author Topic: Measuring acid additions by weight instead of volume  (Read 1451 times)

#### zorch

• Cellarman
• Posts: 56
##### Measuring acid additions by weight instead of volume
« on: August 01, 2012, 12:32:32 PM »
I'd like to start experimenting with using 10% phosphoric acid to acidify my mash and sparge water for my low-SRM beers.    I'm using the Bru'nWater to calculate the amounts to use, but the amounts to use are expressed in milliliters (and partial teaspoons).

I don't really have a good way to accurately measure volumes at that scale.  But I do have a reasonably accurate (0.01 gram) scale.     So if knew the density (g/ml) of my acid, I could just weight it out in grams.

Wikipedia tells me that phosphoric acid has a density of 1.885 g/ml, and that an 85% solution has a density of 1.685 g/ml.     I guess I don't understand the formula one uses to arrive at that 85% value, so I am not sure how to then get to the density of a 10% solution.

I know I could just assume 1g/ml, and it would be kinda close.   I just like knowing stuff.    My best guess is somewhere around 1.05 g/ml.    Does anybody know the actual value (at room temp, sea level, etc).?

#### kramerog

• Brewmaster
• Posts: 650
##### Re: Measuring acid additions by weight instead of volume
« Reply #1 on: August 01, 2012, 12:41:11 PM »
Pretty good guess.  It is actually 1.053 g/l per the CRC handbook.  Just a word of caution, brewing water spreadsheets only give a ballpark number for additions of acid IME.

Alternatively, you can buy a measuring thingy at the pharmacy for measuring liquid medicine to give to kids.  These things are marked in 1-ml increments.
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#### tygo

• I spend way too much time on the AHA forum
• Posts: 2622
• Sterling, VA
##### Re: Measuring acid additions by weight instead of volume
« Reply #2 on: August 01, 2012, 03:22:06 PM »
Alternatively, you can buy a measuring thingy at the pharmacy for measuring liquid medicine to give to kids.  These things are marked in 1-ml increments.

Or you could just have kids and then you end up with dozens of the things
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#### oly

• Cellarman
• Posts: 59
• beervana
##### Re: Measuring acid additions by weight instead of volume
« Reply #3 on: August 01, 2012, 08:38:50 PM »
Pretty good guess.  It is actually 1.053 g/l per the CRC handbook.  Just a word of caution, brewing water spreadsheets only give a ballpark number for additions of acid IME.

Alternatively, you can buy a measuring thingy at the pharmacy for measuring liquid medicine to give to kids.  These things are marked in 1-ml increments.

+1.  Our vet gave us one for the cat medicine, it dispenses 0.1mL increments. Cheap and precise.

#### Delo

• Assistant Brewer
• Posts: 187
##### Re: Measuring acid additions by weight instead of volume
« Reply #4 on: August 02, 2012, 05:53:39 AM »
Or you could just have kids and then you end up with dozens of the things
This actually made me laugh out loud. After over 6 months of ear infections with our daughter, we had a small drawer full of these. They do work great for measuring small amounts of liquids.

#### narcout

• Brewer
• Posts: 427
• Los Angeles, CA
##### Re: Measuring acid additions by weight instead of volume
« Reply #5 on: August 02, 2012, 05:47:12 PM »
I doubt you'll need a level of precission higher than what you would have access to with a standard measuring spoon set.

I use 10% phosphoric acid to acidy my sparge water, and I find that even when I'm using 100% RO water the amount of acid necessary is around 1/4 of a teaspoon (per 3.7 gallons of sparge water).