Milltronics OCM II PL-269, Instruction Manual

Page: 81 / 107

EXAMPLE 2: RECTANGULAR FLUME (BS-3680)
This example considers flow in a rectangular flume with a raised invert (hump), calculated according to the British
Standards Institute specification, BS-3680.
The transducer is mounted 65 cm (minimum 61 cm) above the highest liquid level.
The flume has a capacity if 0.11964 cubic meters per second at full head which is 50 cm.
Thus the distance from the transducer face to the zero-flow level is 65 cm plus 50 cm = 115 cm.
The flume characteristics are:
Maximum flowrate 0.11964 m
3
/second
Maximum head 50 cm
Width of throat 20 cm
Width of approach channel 40 cm
Height of hump 15 cm
Length of throat 100 cm
Water samples are to be taken every 1,000 cubic meters.
The analog current output is to represent flowrate, and the display is to show the flow totalizer.
P0 = 0 Dimensions are in centimeters
P1 = 1 Temperature is Celsius
P2 = 1 BS-3680 Rectangular Flume
U0 = 0.11964 Cubic meters (per sec) for 20 mA output
U1 = 0 Flowrate time units (per sec)
U2 = 50 Full scale head in centimeters at 0.11964 m
3
/S
U3 = 20 Width of throat in centimeters
U4 = 40 Width of approach channel in centimeters
U5 = 15 Hump height in centimeters (zero if no hump)
U6 = 100 Length of throat
P3 = 2 Display flow totalizer in run mode (F2)
P4 = 115 *Distance from transducer to 0 flowrate head in cm.
P5 = 0 Calculate flowrate for all heads(no low head cut off)
P6 = 1 Fail safe high
P7 = 60 Fail safe after 60 seconds without an echo
P8 = 6 Sampler relay contact closure by flow volume
P9 = 1000 Contact closure every 1000 cubic meters
P10 = 0 (relay deadband not applicable)
P11 = 0 Analog output represents flowrate
P12 = 20 Damping rate is 20 seconds for 100% change
P13 = 1 Analog output is 0-20 mA
P14 = 12 Optional logging-file site identification number
P15 = 1 Totalizer multiplier, one unit equals 1 cubic meter
Totalizer overflows every 96 days at full scale.
P16 to P18 not used on this example
* If AUTO ZERO Calibration routine (F12) is used, entry of the current liquid head will cause
P4 = 115 to be deduced and entered automatically.
N.B. Data Logging occurs automatically and requires no specific set-up. However, the data logs will be
meaningless if the CLOCK and CALENDAR are not set to the present time and date. If data logs will
never be used the clock and calendar need not be set.
PL-269 9 – 3