Data Sheet for Product

Siemens Building Technologies CA1N4028 / 11.1998
Landis & Staefa Division 9/12
H
H
100
n
gl
•
The equation for the equal percentage (exponential) curve (Fig. 16) is:
k
v
= k
vo
• e
The slope is not constant here, but changes with H, in accordance with the
same exponential law.
The value n
gl
determines how steeply the curve rises. For any given valve, it
is a constant.
k
vs
k
vr
94.0147
10
0
20
30
40
50
60
70
80
90
100
110
0 102030405060708090100110
[%]
k
v
k
vs
Hub
[%]
H
100
94.0145
H
k
v
k
vs
k
vo
Fig. 16: Equal percentage curve
(theoretical)
Actual curve of a conventional valve
In practice, the (theoretical) equal percentage curve falls away in the
lowest opening range, generally producing a concave characteristic.
At the point where the tangent exceeds the slope tolerance for the first
time, k
v
is equal to k
vr
.
This value is used to define the rangeability of the valve:
Sv =
H
100
94.0146
H
k
v
k
vs
k
vo
k
vr
Tangent
Slope
tolerance
(in accordance with
VDI / VDE)
Fig. 17: Curve in practice (principle)
Fig. 18: M3P20F valve characteristic