How long should a half inch pipe be inorder to hold one gallon of water?

Question

How long should a half inch pipe be inorder to hold one gallon of water?

Answer 1

I got 1176.474 but I'm just a dumb engieer (at least that's what my neice told a neighbor!)

Answer 2

Confused with the first two answers ?

Both different. Can,t tell you what the calculation is using imperial measurements but the formula to calculate the capacity of a round vessel in metrics is

Pi(Pronounced PIE) which is 22 divided by 7  x radius squared x length equals cubic metres divide by 1000 equals litres.

If you do not know the length but know the capacity you need to write the forula as follows

pi x radius squared divided by capacity.

If you go to  www.convertit.com/Go/ConvertIt/Measureme... that is a site where you could convert all measurements to metrics then convert back again.

Hope this helps.

Answer 3

1 gallon = 231 cubic inches

Pi * 1/4" radius squared = 0.1963 square inches cross section

231 cubic inches / 0.1963 square inches = 1176.473 inches long

Answer 4

Well, a US gallon is 231 cubic inches.  These look fine to there.

The formula for the volume of a cylinder is pi * radius ^2 * length.

The radius of a 1/2" pipe is 1/4", or .25" . .

From there,

pi * .25^2  * length =231

3.14159265 * 0.0625 * length = 231

0.19635 * length = 231

(0.19635 * length) / 0.19635 = 231 / 0.19635

length = 1176.471 inches

So Jon M has it right.  The fractional difference is due to rounding, not a big deal.

All of this assumes that we are talking about 1/2" inner diameter pipe -- most plumbing pipe is measured by inner diameter, but not all.  If the 1/2" is outer diameter, then you would need to subtract for the wall thickness and try again.

Also, pipe diameters are nominal -- there is an allowable variance in the diameter, depending upon the type of pipe.  This variance is enough to impact the final measurement.  Water pressure would make a slight difference as well.  Given this, I think it would be best to say one gallon would fill between 1117 and 1235 inches of pipe, or keep it simple and say around 100'.

I never would have guessed that it would take that much pipe to hold a gallon.

Answer 5

Let's see, half inch INSIDE diameter, I assume.

So radius of pipe would a quarter inch, cross section of pipe is (3.14159)/32  squar inches.    A gallon is 231 cubic inches so the pipe must be 231 x 32 / pi = 2352.95