Author: **mark.f** » Tue May 13, 2008 1:06 pm

Or...

Approximate the bends in the elbows with polynomials or other elementary functions, create a 2-d cross section on the xy coordinate plane, choose your endpoints carefully, and use the washer method to calculate the volume of the fitting.

Volume = the integral from a to b of, parenthetically, R<sup>2</sup>-r<sup>2</sup>, where a and b are the endpoints of the curves and R and r are your polynomial approximations.

Or...

Just do a fluid volume measurement. Even though some on this forum are mathematically capable of doing the above if provided a 2-d cross section of a fitting (which is elusive in the first place), mostly all would still just use the fluid volume measurement to save time and frustration.