Math Help Please! - Home Brew Forums

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09-20-2006, 04:31 PM   #1
Brewpastor
Beer, not rocket science

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Feb 2006
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Ok all you people who didn't sleep through math, I need some help.

I want the formula for figuring the METRIC height/depth required in a cylinder with a given diameter to hold particular ounces of water.

For example, how do I calculate how many milimeters of depth I need in a cylinder that is .5 meters across, to hold 64 ounces of fluid?

I want to be able to use a metric ruler as a volume guage for my mash tun. Basically, I want 10 gallons of water so that means I need to fill the tank to such and such a height.

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09-20-2006, 04:37 PM   #2
Dude
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I love lamp.
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09-20-2006, 04:39 PM   #3
Desert_Sky

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my brain hurts now, thanks
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09-20-2006, 04:56 PM   #4
Salizar
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Eugene, Oregon
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So the best way to figure this out is to remeber that 1 ml = 1 gram = 1 cubic centimeter and 1 oz = 29.57 ml (from my calculator). First 64 oz. = 1892 ml or 1892 cubic centimeters. So the volume of the cylinder is equal to 1892 cubic centimeters and also equal to pi*radius^2 *height which is the equation for volume of a cylander. So going through the algebra steps 1892/pi * radius^2 should equal the required height (where radius is half of the distance across or 25 cm). I get .96 centimeters high so to get 64 oz. in your pot you will want to fill it up about 1 centimeter.

09-20-2006, 04:57 PM   #5
2nd Street Brewery

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May 2005
Castleton NY
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This may be simplistic but why can't you take 10 gals of water, pour it into the mash tun and measure the height? Are you going to build the tun and want to know how high to make it?
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09-20-2006, 05:24 PM   #6
Kaboom
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Feb 2006
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Here is the general formula.

Height = (4*Volume)/(Pi*Diameter^2)

You have to convert your volume to cubic mililimeters and your diameter to millimeters before you start.

So for 10 gal and a .5 meter diameter

(4*37854118cmm)/(3.14*500mm^2) = 192mm

Someone might want to double check my numbers. Seems off, but I checked over and over again. Maybe I just can't visualize this. Or I made a stupid mistake.

09-20-2006, 05:24 PM   #7
Pumbaa
I prefer 23383

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Oct 2005
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Quote:
 Originally Posted by Salizar So the best way to figure this out is to remeber that 1 ml = 1 gram = 1 cubic centimeter and 1 oz = 29.57 ml (from my calculator). First 64 oz. = 1892 ml or 1892 cubic centimeters. So the volume of the cylinder is equal to 1892 cubic centimeters and also equal to pi*radius^2 *height which is the equation for volume of a cylander. So going through the algebra steps 1892/pi * radius^2 should equal the required height (where radius is half of the distance across or 25 cm). I get .96 centimeters high so to get 64 oz. in your pot you will want to fill it up about 1 centimeter.
You sure your math is right? 1 centimeter = about .4 inches . . .seems awefully shallow
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09-20-2006, 05:42 PM   #8
Chairman Cheyco
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25x25x3.14=1962.5

That's ml which=1.962l/cm height of the vessel.

Salizar's numbers check out.
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09-20-2006, 05:59 PM   #9
Pumbaa
I prefer 23383

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I knew there was a reason I failed algebra twice . . . I miss read the formula

Quote:
 I want to be able to use a metric ruler as a volume guage for my mash tun. Basically, I want 10 gallons of water so that means I need to fill the tank to such and such a height
Why not just dump a half gallon in at a time and mark where it reaches until you get to what ever volume you think you'll need?
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 Originally Posted by P.J. O'Rourke "There are just two rules of governance in a free society: Mind your own business. Keep your hands to yourself."

09-20-2006, 06:14 PM   #10
Brewpastor
Beer, not rocket science

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Feb 2006
Corrales, New Mexico
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The youth director at the church is a math wiz and so I asked her about this. She did her magic and made me a spreadsheet. So, I now have a really cool Excel spreadsheet that figures this out. It is set up so you enter the desired volume in US ounces, the cylinder's radius in either cm or mm (metric is easier to use, even tenths and all) and it will tell you the depth you need to obtain your volume.

This means that I can use a metric ruler as a gauge for brewing volumns. Say I have a known amount of liquid in my HLT and want 12 quarts into my mash tun. By using a metric ruler I can know what has been transferred.

Now, how do I post the calculator so others can share it?
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