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311
BALANCING VALVES [23]
Q (flow)
Low pressure test point
High pressure test point
Δp
TP
**Tolerance on nominal K for
completely open valve is ±5% (test
according to BS7350)
Flow Measurement
HANDWHEEL
POSITION
Kv (m3/h @ 1bar)
15
20
25
0.5
0.37
0.40
1.40
0.6
0.40
0.44
1.58
0.7
0.44
0.50
1.70
0.8
0.47
0.57
1.80
0.9
0.52
0.64
1.89
1
0.55
0.70
2.00
1.1
0.60
0.75
2.12
1.2
0.64
0.77
2.26
1.3
0.68
0.80
2.40
1.4
0.71
0.84
2.50
1.5
0.75
0.90
2.60
1.6
0.78
0.96
2.74
1.7
0.81
1.00
2.90
1.8
0.87
1.07
3.06
1.9
0.91
1.14
3.27
2
0.94
1.20
3.50
2.1
0.97
1.25
3.76
2.2
1.00
1.29
4.03
2.3
1.06
1.30
4.30
2.4
1.10
1.39
4.56
2.5
1.18
1.50
4.80
2.6
1.26
1.57
4.96
2.7
1.35
1.70
5.10
2.8
1.49
1.85
5.24
2.9
1.63
2.02
5.37
3
1.75
2.20
5.50
3.1
1.93
2.43
5.60
3.2
2.08
2.67
5.71
3.3
2.25
2.90
5.80
3.4
2.35
3.15
5.91
3.5
2.44
3.40
6.00
3.6
2.46
3.61
6.10
3.7
2.50
3.80
6.18
3.8
2.55
3.96
6.26
3.9
2.60
4.06
6.34
4
2.67
4.10
6.40
Formula linking flow Q (in l/s) and
∆
p
are measured at test points (in kPa).
K depends on handwheel position
as indicated in the table. Minimum
flow that can be measured for each
diameter may be calculated by using
the formulae minimum
∆
p that can
be measured by using manometer.
Valves are designed for best
performance when used on a range
previously suggested and as indicated
by BS7350
K
V
. Δ
p.
TP
36
Q
=
�
1,2 3