Orthogonal view of a fiberglass 2-inch Parshall Flume.  Like the 1 and 3-inch Parshalls, the 2-inch was one of the last of the Parshall Flume sizes to be developed.  

The 2-inch Parshall Flume is too small to be used on unscreened sanitary flows as it will eventually clog.  For sanitary flows, the 3-inch size should be used.  The size of the flume is such that it is really only useful for measuring small treated effluents, surface waters, dam seepage, or mine discharge.