2 L1 71 en
5
It is recommended that the length of any straight pipe
preceding the control valve is at least 2 x pipe diameter.
The flow causes a so-called dynamic torque against the
valve disc which attempts to close the valve. In a pipe
elbow the pressure on the outer edge is higher than on the
inner edge.
When installing the valve immediately after a pipe elbow,
the valve shaft must be directed toward the centre point of
the pipe (see Fig. 5). This is especially important when the
valve is used as a control valve.
The valve shaft of a triple eccentric disc valve mounted after
the centrifugal pump must be perpendicular to the pump
shaft (see Fig. 6).
When thus installed, the valve discs will be more evenly
loaded and vibrations otherwise possible in the intermedi-
ate positions will be eliminated.
When mounting the valve it must be in a
closed position
and be carefully centred between the pipe flanges so that
the turning disc does not touch the pipe edge or flange
gaskets.
Use caution when installing valve with Spring-to-open
actuator. Valve must be in closed position during installa-
tion if the disc exceeds the Face-to-face length. Energy sup-
ply for the actuator must be safely fastened and it cannot
suffer damage or break off during the installation.
In case of sudden shutdown of the energy supply the valve
will open unexpectedly due to pre-stressed spring package.
This may cause significant harm to people and material
around the valve.
In valves with certain nominal sizes some flange bolts do
not pass the valve body. The valve body is thus equipped
with grooves, holes or threads (see Section 3.2.1).
Ensure that the disc can turn to the open position after pre-
liminary tightening of the flange bolts. The actuators of
control valves are usually equipped with position stops
which usually only allow the disc to open 80°.
3.2.1
Mounting options
X
Flange bolts pass the neck of the body
UH
Unthreaded holes at the neck of the body
SB
Stud bolts at the neck of the body (L2 always)
BH
Stud bolts at the neck of the body and fraised
holes on the body and flange ring
FH
Unthreaded holes at the neck of the body and
fraised holes on the body and flange ring
XF
Flange bolts pass the neck of the body and
fraised holes on the body and flange ring
HM
Fraised holes on the neck of the body for flange
bolts
—
Flange drilling not suitable
Fig. 4.
Position of the flow balancing trim
Fig. 5.
Mounting after a pipe elbow
Fig. 6.
Mounting after the centrifugal pump
Flow direction B
The recommended
position of the
perforated plate is at
the "top" of the
pipeline, on the
downstream side and
to flow direction B.
Fig. 7.
Minimum pipe inside dimensions
Table 1.
Minimum pipe inside dimensions D/(mm)
Valve size
D
L1CM
L1DM
18
422
400
20
464
443
24
565
536
28
665
30
716
32
762
36
870
40
960
Fig. 8.
Mounting options
