Burkert Type 8635 - Manual (Page 65)

8635 - 63
O
PERATING AND
C
ONTROLLER
F
UNCTIONS
The flow characteristic k
v
= f(s) describes the flow through a valve, expressed by the k
v
value, as a
function of the stroke s of the actuator spindle. It is determined by the shape of the valve seat and the
seat seal. In general, two types of flow characteristic are realized: the linear and the equipercentile.
With linear characteristics, equal changes in stroke ds are allocated to equal changes in k
v
value dk
v
(dk
V
= n
lin
* ds).
With an equipercentile characteristic, a change in stroke ds corresponds to an equipercentile change in
k
v
value
(dk
V
/k
V
= n
equiper
* ds).
The operating characteristic Q = f(s) represents the relationship between the volumetric flow Q passing
through a valve installed in a system and the stroke s. This characteristic contains the properties of the
piping, pumps and consumers. It hence has a different shape from the flow characteristic.
CHARACT
Selection of the transfer characteristic between input signal (position setpoint)
and stroke (correction curve) (S/HART)
Customized characteristic (Characteristic)
Factory setting: CHA LIN
With this supplementary function, you can select a transfer characteristic with respect to setpoint
(position setpoint CMD) and valve stroke (POS) to correct the flow or operating characteristic.
CHA LIN
CHA 1/25
CHA1/33
CHA1/50
CHA 25/1
CHA 33/1
CHA 50/1
CHA FREE 0 XXX
95 XXX 100 XXX
CHARACT Linear characteristic
Equipercentile characteristic 1:25
Equipercentile characteristic 1:33
Equipercentile characteristic 1:50
Inverse equipercentile characteristic 25:1
Inverse equipercentile characteristic 33:1
Inverse equipercentile characteristic 50:1
User-defined characteristic, freely
programmable via fixed poinds