ARI Armaturen STEVI 451 EN - Manual (Page 15)

Rev. 0040306000 0410 Page 15
Operating and installation instructions
3-way control valves - STEVI
®
450 / 451
7.2 Replacement of internal parts
- Remove actuator. (Refer to operating instructions for actuator!)
A special wrench is needed to remove the seatring (pos. 2). It can be obtained from the
manufacturer.
When fitting a new or reconditioned seatring, clean thread and sealing taper in body and
apply suitable lubricant.
Item 7.1.3 describes how to change the plug and stem in valves with a bellow seal
(series 451).
7.2.1 Mixing plug design
DN15-150
- Unscrew seat ring (pos. 2 bottom) and renew or
recondition.
- Slacken screw joint (pos. 19 or 42) by about 1 turn.
- Extract and replace plug (pos. 3) and stem (pos. 5).
Note:
DN 125-150: Bolt new parts together, drill and pin them.
- Assemble in reverse order.
(For tightening torques refer to item 7.3.)
The top seat ring can only be replaced in:
DN 125-150 with standard Kvs values
DN 15-150 with multiple reduced Kvs values
- Dismantle seat ring, plug and stem as described above.
- Loose nuts (pos. 11).
- Detach mounting bonnet (pos. 7).
- Unscrew seat ring (pos. 2 top) and renew or recondition.
(For tightening torques refer to item 7.3.)
- Replace gasket (pos. 9).
- Assemble in reverse order.
(For tightening torques refer to item 7.3.)
- Secure with nuts (pos. 11) and tighten them crosswise.
(For tightening torques refer to item 7.3.)
ATTENION !
Refer to item 10.0 and 11.0 before dismantling the valve.
(bottom)
Fig. 20:
Series 450 DN15-150
with mixing plug