Volume of a tank conversions

showshocka

Member
showshocka
Join Date
Mar 2011
Location
USA
Posts
510
guys. I have cylindrical run tanks that I'm trying to find the total volume of product (water) it will hold. the number that i come up with will have to be converted to inches, thats what they have this field comunicator setup to read in, example
(0inches=0ma 71inches=20ma) put from the pressure transducers. the amount inches factor will read at the operators panel in lbs. how can i covert it to lbs. myself first to check to see if it's reading correctly. I'm not sure how to convert from "a number" that i come up with. the formula i am using is (2 x 3.14 X Radius x height)
2
when i plug this formula in with numbers the radius of the tank is 73 and height is 79.5. which comes out to 18223. how can i convert this to inches then lbs.?
 
You may not be totally lost, but you are ceratinly wandering about a little!

You're not alone. I'm often surprised how many of the questions here are fundamental geometry and physics questions and not at all related to PLCs.

First off, the forumla for area of a circle is pi x r^2. Now, we have to ASSUME that the tank is vertical, not laying on its side. Then volume = area times height. Make sure you use consistent units! In your case the volume will be cubic inches.

Then weight = volume times density. Water weighs nominally 62.4 lbs per cubic foot, and there are 1728 cubic inches in each cubic foot. Therefore the weight is volume x 62.4 / 1728 where volume is cubic inches and weight is lbs.

Your formula will give you the surface area of the tank!
 
The volume of a cylinder (tank) is Pi * radius**2 * height. Now this is for an vertical cylinder. For a real world tank, some corrections may be necessary. if the tank is horizontal, this formula won't help you determine the actual partial volume.
 
I'm totoally lost on what you are after. Can you at least summarize what info you have and what you are trying to calculate?

- is this tank vertical or horizontal?
- is the tank 79.5 or 71 inches?
- is it volume or mass you are after?
- the formula for Volume of a vertical cylindrical tank is (Pi x R^2 X h)
 
In addition to the question of whether the tank is vertical or horizontal, does it have a conical bottom or domed ends. We do this all the time here, so once we have the answers we can help you. Once we know more about the tank its really straight forward to convert a pressure reading from inches of H2O to gallons, pounds, liters, acre-feet, or whatever.
 
Water weighs nominally 62.4 lbs per cubic foot,
Click to expand...
This is usually good enough for government work. If it is not pure water, but tap water with minerals, the weight/cu.ft. will be slightly more. Also the weight of water varies with temperature.
 
Last edited:
harryting said:
Can you at least summarize what info you have and what you are trying to calculate?
Click to expand...


I'm trying to find out what the total weight in lbs. of a vertical cylindrical tank that is 73inches across and 79.5inches high. not including the dome only up to the well line. sorry for the over kill i was thinking too hard while typing.....
__________________
 
The area of your tank is pi*(diameter/2)[su]2[/sup] or 4185.4 in2

One inch of water in the tank gives us 4185.4 in3.

One cubic inch of water weighs 0.036127 lbs, so multiplying all of our terms, including units, we get

(4185.4 in3) * (0.036127 lbs/in3) = 151.21 lbs.
(by including the units and observing that the in3 units cancel out we can double check that we set up the problem right if the answer is in lbs.)

Now we know that the water in the tank weighs 151.21 lbs per inch of water depth.

Now scale your pressure transducer to read in inches H2O. Multiply this value by 151.2 to obtain how many pounds of water are in the tank.
 
Last edited:
More easy

Hi.
I think that this tank will be a Vertical tank.
0 mA = 0.0
20 mA = 79.5

79.5 = 100%

Eg: Max water capacity is 18796
The weight is (18796 * Read Value) / 79.5
 
Last edited:
Tom Jenkins said:
First off, the forumla for area of a circle is pi x r^2. Now, we have to ASSUME that the tank is vertical, not laying on its side. Then volume = area times height. Make sure you use consistent units! In your case the volume will be cubic inches.
Click to expand...
2
that formula is pi X r (right)?
that's times height in inches?, in my case times 79.5inches

Tom Jenkins said:
Then weight = volume times density. Water weighs nominally 62.4 lbs per cubic foot, and there are 1728 cubic inches in each cubic foot. Therefore the weight is volume x 62.4 / 1728 where volume is cubic inches and weight is lbs.

Your formula will give you the surface area of the tank!
Click to expand...
what will that surface be in units?
 
Last edited:

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