ARI Armaturen STEVI 426 EN - Manual (Page 8)

Page 8 Rev. 0040314001 0410
Operating and installation instructions
Straight through control valves - STEVI
®
425 / 426
5.2 Requirements at the place of installation
The place of installation should be easily accessible and provide ample space for
maintenance and removing the actuator. Stop valves should be installed before and after
the control valve to enable maintenance working without draining the piping system. The
valve should preferably installed vertically with the actuator at the top. Inclined or horizontal
installation without supports is permissible only with light actuators.
For this installation position, the two distance columns (or joke) have to be above each
other in the vertical plane.
Permissible servo weights for valves with unsupported horizontal stems:
65 kg for DN300 - 500
The pipes must be lagged to protect the actuators from excessive heat. Sufficient space
must be left for the maintenance of the stem packing.
To ensure that the servo controlled valves function correctly, the pipe run should be straight
for at least 2 x n.d. upstream and 6 x n.d. downstream of the valve.
5.3 Installation instructions concerning actuators
Normally, servo controlled valves are supplied complete with actuator fitted.
It is not permitted to mantle / dismantle actuators with valves operating and service
conditions (temperature and pressure). The actuators must be assemble as describe in the
operating instructions during conversion and maintenance.
During assembly work, the plug is not be turned on its seating at closing pressure.
When retrofitting actuators, the maximum permissible force for valve actuation must be
taken into account:
Fig. 5: Pipeline vertically Fig. 6: Pipeline horizontally
ATTENTION !
Care must be taken with the bellow type valves when actuators are mounted or
removed. (Hold the valve-stem against turning with an open-end wrench!)
200kN for DN 300-500