%P 103-106
%N 1
%J Transaction of the ASAE
%L nwisrl452
%R 0570
%V 29
%D 1986
%A Thomas J. Trout
%T Orifice Plates for Furrow Flow Measurement: Part I - Calibration
%X ORIFICES, due to their discharge sensitivity to
head, are potentially the most accurate open
channel flow measurement device and consequently, the
best device for determining furrow infiltration rates by
the inflow-outflow method. Laboratory calibration
determined that orifices under submerged flow
conditions are insensitive to boundaries as close as one-half
diameter from an edge, allowing practical field use
of multi-holed orifice plates in furrows. Submerged flow
discharge coefficient for square-edged orifices with the
plate thickness less than one-third of the diameter is
0.625. Free flow coefficients vary both with orifice size
and head.