[ossiblue]

Area (open space) of a circle (pipe): A=pi x r2.

Area of an oval (open space of tube): A=pi x r(a)(long radius) x r(b)(short radius).

The value of the area will not change as the shape of the circle is modified. That means, as the circle is crushed, the radius shrinks in one direction but expands in the other so that the area remains the same. Take a measurement of the long and short radii of the blower tube (Outside measurement) and calculate the area. Then, calculate the area the ID of a 2" pipe (3.14 x 1 x 1=3.14 sq. in.) Does the outside area of the blower tube nearly equal the internal area of the 2" pipe?