The ChrisNik 3-Foot Extension Arm 1736ARM connects to the Pipe-Mic II and provides construction and surveying professionals with an additional 3 feet for measuring pipe inverts or pipe diameters. This extension arm is especially helpful for projects involving larger diameter manholes. It is used with grade rods that have graduations in feet, tenths, and hundredths of a foot.
How It Works
After removing the 2-foot arm, the 3-foot extension arm snaps into the shoulder bolt of the Pipe-Mic II. Next, place the 4-inch wheel of the arm on the invert of the pipe. Then, lift your leveling rod straight up by rotating the extension arm. Once the wheel reaches the top of the pipe, take your measurement, add 0.33, and that sum is the size of the pipe.