Instruction manual

Page 110
Special Devices
Special DevicesSpecial Devices
Special Devices
Point of Measurement
The transducer must be above the maximum head P704 by at least the near
blanking distance P107.
In the case of a Palmer Bowlus flume the point of head measurement
should be half the value of Dim “A” P710 upstream of the device.
For a H-Flume the head measurement is taken at a point downstream from
the flume entrance as detailed in the table below:
Flume size
Point of Measurement
Dim. “A” P710
cm
Feet
cm
inches
15.25
0.5
4.7
1.88
23.00
0.75
6.7
2.69
30.05
1.0
9.1
3.63
45.70
1.5
13.5
5.38
61.00
2.0
17.9
7.19
76.20
2.5
22.5
9.00
91.45
3.0
27.2
10.88
137.15
4.5
40.5
16.19
V-notch angle weirs, the head is measured upstream of the weir plate at a
minimum distance of 3 times maximum head to ensure the surface of the
liquid is not effected by turbulence or drawdown. See Exponential devices,
above, for further details.