Author Topic: How to calculate Kettle volume  (Read 520 times)

Offline porkchopexp2

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How to calculate Kettle volume
« on: January 26, 2018, 07:11:07 PM »
I'm trying to find the equation to calculate the height of volume in my kettle.  I'm trying to figure out what size wort chiller will work.  I know how to calculate the total volume of a kettle, just don't know how to calculate the height of the liquid in the kettle.  For example, if I put 1 gallon of water in a 3 gallon kettle, the water height is 2.94 inches.  I don't want to keep running to my computer to use the calculator, which won't show the equation. And I don't want to keep multiplying the number of gallons I pour in a kettle by 2.94 inches, because I know that's 1 gallon, but that will change depending on the size of the kettle. 

Offline Big Monk

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Re: How to calculate Kettle volume
« Reply #1 on: January 26, 2018, 07:19:36 PM »
I'm trying to find the equation to calculate the height of volume in my kettle.  I'm trying to figure out what size wort chiller will work.  I know how to calculate the total volume of a kettle, just don't know how to calculate the height of the liquid in the kettle.  For example, if I put 1 gallon of water in a 3 gallon kettle, the water height is 2.94 inches.  I don't want to keep running to my computer to use the calculator, which won't show the equation. And I don't want to keep multiplying the number of gallons I pour in a kettle by 2.94 inches, because I know that's 1 gallon, but that will change depending on the size of the kettle.

You assume a perfect cylinder:

V = (PI) * (r^2) * h

Rearranging  you get:

h = V / (PI) * (r^2)

So:

h (in) = Vwort (gallons) / 3.14159265359 * (r (in) ^2) * 0.004329


The 0.004329 factor converts cubic inches to gallons. Alternately, if using liters and cm, you use 0.001.
« Last Edit: January 26, 2018, 07:32:19 PM by Big Monk »
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Offline lupulus

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Re: How to calculate Kettle volume
« Reply #2 on: January 26, 2018, 10:13:41 PM »
I'm trying to find the equation to calculate the height of volume in my kettle.  I'm trying to figure out what size wort chiller will work.  I know how to calculate the total volume of a kettle, just don't know how to calculate the height of the liquid in the kettle.  For example, if I put 1 gallon of water in a 3 gallon kettle, the water height is 2.94 inches.  I don't want to keep running to my computer to use the calculator, which won't show the equation. And I don't want to keep multiplying the number of gallons I pour in a kettle by 2.94 inches, because I know that's 1 gallon, but that will change depending on the size of the kettle.

You assume a perfect cylinder:

V = (PI) * (r^2) * h

Rearranging  you get:

h = V / (PI) * (r^2)

So:

h (in) = Vwort (gallons) / 3.14159265359 * (r (in) ^2) * 0.004329


The 0.004329 factor converts cubic inches to gallons. Alternately, if using liters and cm, you use 0.001.
Life is so much simpler with metric

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Offline dmtaylor

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Re: How to calculate Kettle volume
« Reply #3 on: January 26, 2018, 10:17:34 PM »
Life is so much simpler with metric

...And so much more difficult either way when pi is involved.  Not much we can do about that!  :)
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Offline lupulus

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Re: How to calculate Kettle volume
« Reply #4 on: January 26, 2018, 10:20:37 PM »
Life is so much simpler with metric

...And so much more difficult either way when pi is involved.  Not much we can do about that!  :)
If you type pi in the Google bar it will do the math for you

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Offline lupulus

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Re: How to calculate Kettle volume
« Reply #5 on: January 26, 2018, 10:21:18 PM »
Life is so much simpler with metric

...And so much more difficult either way when pi is involved.  Not much we can do about that!  :)
If you type pi in the Google bar it will do the math for you

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Most calculators have pi as well

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Offline porkchopexp2

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Re: How to calculate Kettle volume
« Reply #6 on: January 27, 2018, 04:54:09 AM »
Thank you very much for the information.  My wife came home from work and conducted a class on how to calculate everything.  I think she should be making the beer, and I'll drink it.

Offline mabrungard

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Re: How to calculate Kettle volume
« Reply #7 on: January 27, 2018, 02:44:57 PM »
A wide open kettle isn't that hard to calculate the heights for various volumes, but for those of you with extra stuff in the kettle like a chilling loop, then the only manageable way is to find a suitable small container (gallon jug) and calibrate that container to verify that filling the container to a certain level gives you the volume of liquid that you expect. (a gallon of water weighs 3785 grams)

Then you start adding containers of water, one by one to enable you to mark or measure what the depth is for that volume.
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Offline BrewArk

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Re: How to calculate Kettle volume
« Reply #8 on: February 01, 2018, 10:17:03 PM »
A wide open kettle isn't that hard to calculate the heights for various volumes, but for those of you with extra stuff in the kettle like a chilling loop, then the only manageable way is to find a suitable small container (gallon jug) and calibrate that container to verify that filling the container to a certain level gives you the volume of liquid that you expect. (a gallon of water weighs 3785 grams)

Then you start adding containers of water, one by one to enable you to mark or measure what the depth is for that volume.
Since my kettle isn't cylindrical, this is the method I'd prefer.  I got an old hockey stick, added a gallon, and put a line with a Sharpie just above the wet spot,  added another gallon and another line...
Beer...Now there's a temporary solution!

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