Milltronics MultiRanger Plus - Page 64

An important consideration in OCM applications is that many primary measuring
devices have the potential of running dry. In such cases, it must be insured that the
range extension ( P-87 ) is sufficient so that the floor of the channel or of the
converging section of the flume can be read. Otherwise, false readings may be
obtained indicating flow.
OCM Example
9" Parshall Flume
Q = 1.98 H
1.53
where Q = flow rate, MGD ( million gallons per day ),
H = head, feet
» max flow rate - Q max = 4.112 MGD
= 4,112,000 gal. / day
» max head - H max = 1.61
» transducer is mounted 3 ft above the zero flow level
» max flow rate display = 4,112
i.e. one count = 1000 gal.
transducer
bottom of weir notch,
0 head
channel bottom
margin
d
depth
% range
extension
P-87
+ 10%
P-3
range
P-87 = d x 110
P-3
PL-443 6 – 30