Instrument for Testing the Roundness of the Inner Wall of a Pipe or Other Hollow Cylinder

FIG. 1 is a top view of the apparatus of the present invention;

FIG. 2 is a right view thereof, the left side view being a mirror image thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a rear view thereof, with the valve closed;

FIG. 5 is a rear view thereof, with the valve open;

FIG. 6 is a front view thereof, with the valve closed;

FIG. 7 is a front view thereof, with the valve open;

FIG. 8 is a rear perspective view thereof;

FIG. 9 is a side perspective view thereof; and,

FIG. 10 is a side exploded view thereof.

The broken lines shown represent environmental subject matter and form no part of the claimed design.