Calculating The Volume Of Cylinders

cm11599ps · 06/05/2011, 07:40 AM

I'd like to calculate how many gallons are in my assorted cans. I have one Brute can that functions as my ATO that I'd like to dose my mag into. I believe the can states it's a 32 gallon can. I also have 2 Home Depot orange buckets that are supposed to be 5 gallons.

I found an online calculator and it states my 32 gallon cans can actually hold around 38 gallons if filled to the top. It states the HD buckets can hold 6 gallons when filled to the top.

Here's the too. Do you think it's an accurate figure? http://www.theaquatools.com/volume-calculator

frankpayne32 · 06/05/2011, 08:02 AM

volume of a cylinder = pi x radius squared x height. Use inches for the height and radius and that will give you an answer in inches cubed. Then multiply that number by 0.00432900433 to get an answer in gallons. This will give you a precise answer.

Rybren · 06/05/2011, 08:08 AM

Remember that the brutes are not true cylinders - they are narrower at the bottom. Therefore, if you use the bottom radius, the calculated volume will be lower than the actual. If you use the top radius, the calculated volume will be higher than actual.

sirreal63 · 06/05/2011, 08:26 AM

Rybren is right and the solution is take the diameter from the middle of the Brute, as it decreases at the same rate it increases, so the middle is close to accurate.

To make calculating volume easier, I use this one.

http://reef.diesyst.com/volcalc/volcalc.html

snorvich · 06/05/2011, 09:49 AM

Quote:

Originally Posted by frankpayne32

volume of a cylinder = pi x radius squared x height. Use inches for the height and radius and that will give you an answer in inches cubed. Then multiply that number by 0.00432900433 to get an answer in gallons. This will give you a precise answer.

Exactly. Remember that most things you buy, e.g. Brutes are not truly cylinders. However, if you measure the bottom radius squared times pi and then similar for the top, you can approximate by taking the total height times the average of the two circular areas.

noahm · 06/05/2011, 10:10 AM

Quote:

Originally Posted by snorvich

Exactly. Remember that most things you buy, e.g. Brutes are not truly cylinders. However, if you measure the bottom radius squared times pi and then similar for the top, you can approximate by taking the total height times the average of the two circular areas.

You like to make work for yourself

the middle diameter will do as the D-average rather than calculating out average areas.

Funny thing is, all my early life they rammed pi*r^2 down our throats, but engineers all use pi*d^2/4 since, really who measures a radius?

To the OP, remember as well, that these containers are designed for a certain fill height (often one of the support rings), so they will usually hold a bit more than specified if filled to the brim.

06/05/2011, 07:40 AM	#1
cm11599ps Registered Member Join Date: Apr 2010 Location: Port Jefferson Station, NY Posts: 1,413	Calculating The Volume Of Cylinders I'd like to calculate how many gallons are in my assorted cans. I have one Brute can that functions as my ATO that I'd like to dose my mag into. I believe the can states it's a 32 gallon can. I also have 2 Home Depot orange buckets that are supposed to be 5 gallons. I found an online calculator and it states my 32 gallon cans can actually hold around 38 gallons if filled to the top. It states the HD buckets can hold 6 gallons when filled to the top. Here's the too. Do you think it's an accurate figure? http://www.theaquatools.com/volume-calculator __________________ LIRA Member Current Tank - 55 gallon. Custom CLF1 sump, fuge, overflow & SVS2-24 skimmer from Lifereef. 4x54 Watt AquaticLife T5 HO Light Fixture W/ 4 Lunar LEDs. 2 EcoTech MP40's, 70lbs assorted

06/05/2011, 08:02 AM	#2
frankpayne32 Registered Member Join Date: May 2008 Location: Pennsylvania Posts: 1,177	volume of a cylinder = pi x radius squared x height. Use inches for the height and radius and that will give you an answer in inches cubed. Then multiply that number by 0.00432900433 to get an answer in gallons. This will give you a precise answer. __________________ Frank Payne Advice to new hobbyists: listen to people that have a tank you would like to have one day, not to those with a high post count. Current Tank Info: 125 gallon in-wall (build thread is my homepage).

06/05/2011, 08:08 AM	#3
Rybren Registered Member Join Date: Apr 2009 Location: Ottawa, Canada Posts: 1,642	Remember that the brutes are not true cylinders - they are narrower at the bottom. Therefore, if you use the bottom radius, the calculated volume will be lower than the actual. If you use the top radius, the calculated volume will be higher than actual. __________________ 120G Mixed Reef, 28G AIO zoa/pipefish tank

06/05/2011, 08:26 AM	#4
sirreal63 Go Spurs Go!!! Join Date: Dec 2004 Location: Meadowlakes Texas Posts: 13,357	Rybren is right and the solution is take the diameter from the middle of the Brute, as it decreases at the same rate it increases, so the middle is close to accurate. To make calculating volume easier, I use this one. http://reef.diesyst.com/volcalc/volcalc.html __________________ Jack No One has ever been seriously injured by using the search function. Alcohol, Tobacco and Firearms should be a convenience store, not a government agency. Current Tank Info: Reefing the Pentagon.

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