%0 Journal Article
%A Trout, Thomas J.
%D 1986
%F nwisrl:452
%J Transaction of the ASAE
%N 1
%P 103-106
%T Orifice Plates for Furrow Flow Measurement: Part I - Calibration
%U https://eprints.nwisrl.ars.usda.gov/id/eprint/452/
%V 29
%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.