18.4.17
Modulating Valves Type: VSR
4. Installation of the Modulating valve
12
5 .
C o m m i s i o n i n g
Normally, the GUTH modulating valve is supplied fully assembled and set according to specifica-
tions. It is assumed that the installation and connections have been carried out according to Section
4.
6 .
C h a n g e s t o t h e M o d u l a t i n g v a l v e
6 . 1
Changing the Kvs Value and the Flow Rate Curve
The relationship between the spindle position (travel) and the free opening cross-section at the
cone and therefore the flow volume for the liquid or gaseous medium depends on the shape and
dimensions of the cone as well as the seat diameter of the interchangeable seat ring. If a change
in the modulating range is required, then the Kvs value determines the selection of the appropriate
cone seat combination.
According to the data sheet for the GUTH modulating valve (see Section 9), several Kvs stages for
each nominal width are available. Also, there is a general distinction between cones with a linear
characteristic curves and ones with equal percentage characteristic curves.
Assemblies consisting of the seat ring and cone with spindle can be interchanged very readily as
follows:
For standard modulating valves with a simple cone seat according to cone position "K1", the
actuator with lantern can be lifted out of the housing by releasing the upper housing clamping
ring (clamping bracket). Care must be taken to ensure that the cone is not damaged by coming
into contact with other components.
For cones positioned according to "K2", the housing must be removed after releasing the pipe
connections and opening the lower clamping ring. The same applies to modulating valves with
several housing sections. There, too, a housing connection must be released at a suitable point
and the modulating valve removed from the plant after opening pipe connections. In exceptional
cases it may be necessary to leave the modulating valve installed in the plant. In such cases
at least that housing section must be removed that allows for the spindle to be withdrawn. This
is true especially for double-seat cones with cone position "K3" as well (mixer valve arrange-
ment).
Especially with modulating valves used as distribution elements with cone position 'K4', we rec-
ommend completely removing the modulating valve from the installation, as an open-ended
spanner must be used to open the spindle by unscrewing the lower cone so that the seat ring
can be removed. After the corresponding clamping connection has been released, the seat rings
can be removed manually between two housing sections or between a housing section and
pipe connecting piece. In the case of the modulating valve used as distribution element already
described above, the rings can be removed after opening the spindle where the latter is sep-
arated.
NOTICE
• To prevent the cone / seat from colliding, the actuator spindle must be aligned flush to the valve
spindle (see section 7 . 4 page 17).
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