Bulk Tank Volume

[Brian Ryther]

I purchased a milk bulk tank this weekend. The seller wasn't sure of the volume. The dip stick has graduated marks that go up to 780. When I measured the tank and converted the area to gallons (square feet x 7.48) I came up with about +500 gallons. Does anybody have any ideas what the dip stick is indicating?

[Clan Delaney]

I purchased a milk bulk tank this weekend. The seller wasn't sure of the volume. The dip stick has graduated marks that go up to 780. When I measured the tank and converted the area to gallons (square feet x 7.48) I came up with about +500 gallons. Does anybody have any ideas what the dip stick is indicating?

Why, 780 units of something, of course!

Maybe it's a measure of contributing cows?

[maplecrest]

the dip stick is set to a chart on the milk house wall where the tank came from to figure the pounds of milk in the tank at time of pick up by bulk truck

[Thompson's Tree Farm]

Most bulk tank dip sticks are marked by 32nd of an inch. Tanks are set in place and then calibrated by the bureau of weights and measures. Water is added to the tank in 10 gallon increments and then measured on the stick. Then an estimation is made of what each 32nd of an inch would be in lbs of milk. Each gallon is converted to 8.6 lbs (the weight of a gallon of milk). For your purposes, your estimation is probably the best way to go. A 500 gallon tank was a common size 30 to 40 years ago. Usually there is also a p[late somewhere on the tank that will indicate its volume in gallons. Usually located on the end where the wiring and refrigerant entered. Hope this helps.

[Hurdhaven Farm]

The dip stick on all the bulk tanks I know of have marks that are keyed to a bulk tank chart. The chart usually comes with the tank. When a bulk tank is moved it needs to be level for the chart and dip stick to match up. Dairy farmers are paid by the CWT(100 lb.) of milk so the chart lists the pounds of milk corresponding to each measurement. Milk is 8.6 lb/gal. In addition there should be a data plate on the tank somewhere with a model and serial number and capacity. Case you are wondering I was a Dairy Farmer for over 25 years.

[Brian Ryther]

The name plate had been removed. I pulled the inner tank from the outer tank. There were marks made in marker that said 25/500. Thanks for info.

[Chad802]

I`ve picked up a round bottom tank. The person i got the tank from said it
was 300 or 500 gallons but was not sure. I was wondering if there was a formula to figure how many gallons the tank holds?

[OGDENS SUGAR BUSH]

RADIUS squared x 3.14 x length= gallons

[StewieSugar]

Ah, a math problem.

"radius squared times Pi times length" will get you the volume of cylinder in cubic inches, but I think the formula is a bit different for a common rounded-bottom (flat top) tank. It's a multi-step problem, but it's not too bad if you have a tape measure, pencil, and calculator.

I've attached a rough sketch to help, but I'm assuming the tank might have some straight side walls.

You need three measurements:
Width of tank across the top = W
Height of tank = H
Length of tank = L

Measure these in inches (not feet, meters, ...)

From the measurements, you need to calculate a few key dimensions.

Radius of bottom = R = 0.5 * W (half the width)
Height of side walls = S = Tank height minus half the tank width = H - (0.5 * W)

If the height of the side walls as calculated above turns out to be a negative number, then your tank is not exactly round. For a rough estimate, I'd simply assuming the side walls are zero (H = 0); it will get you close.

The bottom of the tank is semi circle, and it's cross sectional area = Ac = 0.5 * 3.14 * R * R

You then need to calculate the cross sectional area of the volume within the side walls = As = Width times side wall height = W * S

Now, add the area of the semi-circle and area of the side walls to get the total cross sectional area = A = Ac + As

From here, calculate the volume of the tank in cubic inches by multiplying the total cross sectional area by the length = Vin = A * L

To convert this to gallons, divide the volume in inches by 231 = Vgal = Vin / 231.

Putting it all together (messy, I know)

Vgal = L * [(W * S) + (0.5 * 3.14 * R * R)] / 231
= L * {[W * (H - W/2)] + (0.4 * W * W)} / 231

[WESTVIRGINIAMAPLER]

I think most of them have a number on them somewhere if you look on one end or the other. It may not say gallons, but will likely have a number, but I stand to be corrected if I am wrong.

[the old guy]

The Round Tank I Purchased Measures 3' X 6' Roughly, The Capacity On The Tag Is 430 Gallons.

The Old Guy

[Chad802]

I looked all over the tank and couldnt find any numbers. So we measured the tank up ended up with 480 gallons.Thats close enough to 500 gallons.Thanks for the formulas.Its nice to know how big your tanks are.