Xylem Flow Converter 713 - Manual (Page 4)

4
Determination of Ce for different values of b/B.
Rectangular sharp edged weir without side
contraction:
The sides of the channel must continue at minimum 0,3
x h
a max.
after the weir.
h
a
= height
h
b
= depth below edge in [m]
B = flume width in [m]
L = distance to sensor,
4 to 5 × h
a max.
The following limitations apply for the values of h
a
/h
b
, h
a
,
h
b
and b:
h
a
/h
b
= max. 1,0
h
a
= min 0,03, max 0,75 m
h
b
= min 0,10 m
b = min 0,30 m
Formula: (Rehbock equation)
Q = 3600 × Ce Ч 2/3 Ч 2g × b × h
e
1,5
where: Q = flow in m
3
/h
b = width of edge in [m]
Ce = 0,60+0,083 h
a
/h
b
h
a
= height in [m]
h
e
= effective height in [m]
h
e
= h
a
+k
h
, k
h
= 0,001
g = acc. due to gravity = 9,81 m/s
Triangular weir
according to ISO 1438
ß = minimum 45°
d = 1- mm
h
a
= height in [m]
h
b
= depth below edge in [m]
B = flumewidth in [m]
L = distance to sensor,
4 to 5 × h
a max.
The following limitations apply:
α = 0° - 100°
h
a
/h
b
= max 0,4
h
a
/B = max 0,
h
a
= min 0,06 m
h
b
= min 0,09 m
Formula: (Kindsvater-Shen).
Q = 3600 × Ce Ч 8/15 Ч 2g × tg(α/) × h
e
,5
where: Q = flow in m
3
/h
h
a
= height in [m]
h
e
= the effective height in [m]
h
e
= h
a
+ k
h
, k
h
= 0,001
g = acc. due to gravity = 9,81 m/s
α = aperture angle
β
d
The following limitations apply for the values of h
a
/h
b
, h
a
,
h
b
and b:
h
a
/h
b
= max. ,5
h
a
= min 0,03 m
h
b
= min 0,10 m
b = min 0,15 m
(B-b)/ = min 0,10 m
h
a
h
b
h
a
h
b