Xylem Flow Converter 713 - Manual (Page 7)

7
Venturi flume - long throated
according to ISO 1438
The following formula and diagram concern the long
throated Venturi flume.
713 follows the calculation method for long throated
Venturi flumes described in ISO 1438. The connec-
tion between level and flow is complex and can not be
described in a simple formula. When dimensioning the
following simplified formula can be applied.
Q = 6495 x b x h
a
1,5 (NB: not ISO 1438!)
where:Q = flow in [m 3 /h]
b = width in the flume in [m]
h
a
= water level before the narrowing
L = distance to the sensor = 3 - 4 x h
a max
Q/h diagram for the long throated Venturi flumes,
the height h
a
is shown as a function of the flow Q.
Size b H Max Flow
5" (DN 10) 150 mm 35 m 3 /h
5'' (DN 120) 300 mm 120 m 3 /h
6'' (DN 160) 300 mm 150 m 3 /h
8'' (DN 200) 320 mm 200 m 3 /h
8'' (DN 200) 520 mm 450 m 3 /h
Table showing the size of b, and max. flow for the
Venturi flume - Khafagi.
Venturi flume - Khafagi
The following formula and diagram concern the Khafagi
Venturi flume.
The flow is calculated from the following formula.
Q = 678 x b x h
a
1,5 + 38 x h
a
,5
where:Q = flow in [m 3 /h]
b = width in the flume in [m]
h
a
= level
L = distance to sensor = 3 - 4 x h
a max
H = height of the flume
120mm
160mm
200mm
120mm
160mm
200mm
h
a h
a
L
b L
b
Q/h diagram for the Khafagi Venturi flumes, the
height h
a
is shown as a function of the flow Q.
H