Instruction manual

Page 93
Point of Measurement
The transducer must be above the maximum head P704 by at least the near
blanking distance P107.
For Suppressed/ Contracted Rectangular, Trapezoidal and V-notch,
weirs, the head is measured upstream at a minimum distance of 3 times
maximum head from the weir plate to ensure the surface of the liquid is not
affected by turbulence or drawdown. (See DRWG . 1 )
In the case of a Venturi flume the point of measurement should be 150 mm
(6 inches) upstream from the beginning of the converging section and for
a Parshall flume 2/3 the length of the converging section upstream of the
throat section. See DRWG 2 and 3 )