Best way to measure volume of vessel without knowing dimensions

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09659

09659

0
In The Industry
Feb 7, 2013
138
Pool Country
What is the best way to measure the volume of a vessel without knowing the dimensions of the vessel?

I was thinking of adding calcium chloride and measuring the increase. I would use an extra large test sample to get more precise results. Then I could correlate the test results to the dosage requirements on the container of the calcium chloride.

Any better way to do this?

Thanks
 
There is precision error in any test. I would not add any chemicals for the sake of coming up with a volume unless you actually need the chemicals.

You can get a general trend over the course maintenance by using PoolMath and testing after any chemical addition to dial in the pool volume.
 
What do you mean "without knowing the dimensions of the vessel"? Why don't you just measure it? Here are some suggestions if the shape/depth is complex and not a standard rectangle or square:

1. Find the pool builder and ask them.
2. Check local permits/records, if they don't have volume they will often have sq. footage.
3. Break up sections of the pool into reasonable rectangular sections and measure volume for each section then add them together. If you want to get crazy like I did, use some graph paper and draw the pool to scale, then do your section measurements. Do the best you can to get close, but feel okay if you're inaccurate. After you do that you'll be able to move the estimate up/down through chemical maintenance and Pool Math as jblizzle suggested. I got within 1,000 gallons upon my graph paper method which was only 7% off after I refined it. Even 7% is somewhat immaterial to the Pool Math calculations.
 
Measuring with chems can be tough especially with chlorine because it is not always the labeled strength. Dry chemicals is a little easier but you need accurate measurements which is not always possible with test kits.

The following method gives both surface area and volume which can be useful when you need to replace some water because you can calculate the drain depth.

Using either the house water meter or hose meter take a before reading then add enough water to the pool to raise the pool level 1" then take an after reading to get gallons per inch. Some house meters are in cu-ft already so you may need to take that into account.

Surface area (sq-ft) = gallons per inch / 7.48 * 12 = cubic feet per inch * 12

To get volume you can estimate the average depth by just taking the average of the shallow end and deep end. Depending on the type of pool and layout, you may need to adjust the depth due to stairs, benches and sloped walls. My adjustment was about 25% off the average depth (6 ft -> 4.5 ft) but I have fairly large stairs and a couple of benches.

Volume (gallons) = Surface Area (sq-ft) * Average Depth (sq-ft) * 7.48

The surface area is fairly accurate but the average depth less so but you can then confirm/modify using the chem method when available/accurate. Over time, you should be able to narrow it down further every time you add chems.
 
09659 said:
What I mean is, do pool builders and plasterers measure the square footage by the horizontal plane over the vessel or the actual surface area of all the surfaces that touch the water?
Click to expand...

I think it would depend on which you were interested in.

If I were a plasterer, I'd be interested in the total square footage that contacts the water because that would determine how much plaster I have to purchase and how long it would take to lay that plaster down.

If I were a pool cover salesman, I would be interested in the square footage defined by the horizontal plane over the vessel.

Neither of those are measures of volume, which is likely what the homeowner is most interested in for filling and chemical additions.
 

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Semantics: the meanings of words and phrases in a particular context.



Surface Area =

Average Width multiplied by Average Length



Internal Area =

Average Width multiplied by Average Length

plus

Perimeter multiplied by Average Depth



Volume =

Average Width multiplied by Average Length multiplied by Average Depth
 
I see, internal area is a rough approximation of the surface area that needs to be plastered. More specifically, the area that needs to be plastered if the pool is a rectangular prism (which pools aren't).
 
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