Water Volume by Height of Cylindrical Vessel

[KingKong]

If I have a pot that is a cylinder, how do I work out the volume of water inside based on height? ie 43cm diameter means 1L will be ?? deep in the pot. 10L would be ?? deep in the pot etc.

I'm sick of measuring out 38 litres using a 2L jug and would like to just be able to measure a mark to fill to. (For a biab system)

I know I read the method for this some where. Link me, if this has been posted before I couldn't find it.

 

[verysupple]

So you didn't pass maths at school?

Volume of a cylinder:

V = pi * r^2 *h

V = volume
pi = not the thing you eat, the maths one
r = the radius of the circular end
^ = "to the power of"
h = height

If you measure in cm then you answer is in cm^3 (mL)

 

[QldKev]

You have not thought of marking your volumes onto the pot? Even a permanent market will last a long time, otherwise an engraver is not expensive.


But school maths will answer your question, pi × r2 × h

edit: beaten by verysupple

 

[KingKong]

No maths was not a strong point. I dont know what primary school you when to kev, you must of been in the advanced class.


But if I need to work backwards from the volume to the height not from the height to the volume I would need a different equation wouldnt I . Algebra was a fair few years back now.

 

[QldKev]

Punch your numbers here
http://www.basic-mathematics.com/volume-of-a-cylinder-calculator.html

Take a guess at the height and punch it in, and then change the height depending on result

edit: Hint try 26.2

 

[krausenhaus]

Here's a derivation of the above formula that might be useful:

h = 4000*N/(pi*D^2)

Where h is height in cm, N is the number of litres you want and D is the pot diameter in cm.

So you can use that to find out the increment height for 1L or 10L or whatever else you want.

Won't be completely accurate if you've got pickup tubes, heating elements etc. in there or the pot isn't perfectly cylindrical (i.e. curved bottom).

The brackets are important!

 

[KingKong]

Thanks all. Telling me I need 26.2 cm height for 38L in my pot. Looking at it, seems a bit short of normal. I only have a pick up tube and tap thread inside so should not be to far off, bottom of my pot has a small curve to it though which may effect the results. Looks like Im measuring it out with the jug again.

Might mark it this time. What would you suggest Kev permanent marker in the pot?

 

[krausenhaus]

Thanks all. Telling me I need 26.2 cm height for 38L in my pot. Looking at it, seems a bit short of normal. I only have a pick up tube and tap thread inside so should not be to far off, bottom of my pot has a small curve to it though which may effect the results. Looks like Im measuring it out with the jug again.

Might mark it this time. What would you suggest Kev permanent marker in the pot?

You can also measure out a few jugs worth until you get past the base, mark it and then use the formula to get the heights above that. Less jug filling.

 

[Bribie G]

wee calculator

 

[KingKong]

wee calculator

That is a very good calc for what I want. Bookmarked!

 

[QldKev]

I have a 5L jug I use to measure out all my pots, and then mark either the pot or the sight-gauge with permanent markers

Marking in my 1V. You do need to be careful when cleaning not to scrub them out. But after a couple of touch-ups I scrub them out and redo them. My old BIAB system I used to redo them yearly.

And my sight gauge on the HLT from my 3V, the red line is 40L mark and the others are 5L increments.

 

[Dan Pratt]

this is what i use each brew, shoudl probably make a cheet sheet so i can just measure and refer to teh sheet.

http://www.online-calculators.co.uk/volumetric/cylindervolume.php

 

[QldKev]

wee calculator

Are you measuring how much you wee? h34r:

 

[booargy]

measure the depth of the pot and divide it by how many litres.

 

[tavas]

Weigh it. 1 kg = 1 litre.
Bathroom scales would be sufficient.

 

[Edak]

I marked my volumes on a stainless dip stick, which I put into my pot when I need to measure. Calibrated it once using 5L and 2L increments, marked with a punch, I clean it after each brew and never need to worry about wiping off the marks. See it in my other thread.
http://aussiehomebrewer.com/topic/72195-perfect-day-to-brew/?p=1030300

 

[KingKong]

I marked my volumes on a stainless dip stick, which I put into my pot when I need to measure. Calibrated it once using 5L and 2L increments, marked with a punch, I clean it after each brew and never need to worry about wiping off the marks. See it in my other thread.
http://aussiehomebrewer.com/topic/72195-perfect-day-to-brew/?p=1030300

What a simple but great idea. Brewing like a servo attendant.

 

[mikec]

You have not thought of marking your volumes onto the pot? Even a permanent market will last a long time, otherwise an engraver is not expensive.

I number punched my aluminium pot. But it was a few mm thick and aluminium is nice and soft and doesn't rust.

Setting up a big new SS one now - and am worried a number punch is going to damage it, leading to rust etc. Engraving would be just as bad, no?

 

[QldKev]

I number punched my aluminium pot. But it was a few mm thick and aluminium is nice and soft and doesn't rust.

Setting up a big new SS one now - and am worried a number punch is going to damage it, leading to rust etc. Engraving would be just as bad, no?

Engraving would be ok if you used an engraver that has not been used on metals other than stainless. The other thing depending on how good you are at eyeing levels and transferring it onto the outside, the marks do not need to be on the inside of the pot.

The kettle on my 3V

 

[Edak]

What a simple but great idea. Brewing like a servo attendant.

Thanks, but I don't get the servo attendant remark. Maybe I am too young for this?