ARI Armaturen STEVI 471 EN - Manual (Page 8)

Page 8 Rev. 0040305000 0410
Operating and installation instructions
Straight through control valves - STEVI
®
470 / 471
6.0 Putting the valve into operation
7.0 Care and maintenance
Maintenance and maintenance intervals have to be defined by the operator according to
the service conditions.
7.1 Replacement of stem sealings
7.1.1 PTFE V-ring unit design
PTFE V-ring unit (pos. 11) consisting of: 1 backing ring
4 sealing rings
1 cover ring
Owing to the installed compression spring (pos. 14), this
stem packing is self-adjusting. If the stem starts leaking, the
ring pack is worn out and must be replaced.
Replacement of PTFE V-ring unit:
- Remove actuator.
(Refer to operating instructions for actuator!)
- When replacing PTFE V-ring unit (pos. 11), make sure that
the parts are installed in the correct order and positions
(refer to Fig. 10).
Damaged stems must also be replaced (refer to item 7.2 for
instructions) since a new ring pack will soon start leaking
again if the stem is damaged.
ATTENTION !
- Before putting the valve into operation, check material, pressure, temperature
and direction of flow.
- Regional safety instructions must be adhered to.
- Residues in piping and valves (dirt, weld beads, etc.) inevitably lead to leakage.
- Touching the valve when it is operating at high (> 50 °C) or low (< 0 °C) media
temperatures can cause injury.
Affix warning notice or protective insulation as appropriate!
Before putting a new plant into operation or restarting a plant after repairs or
modification, always make sure that:
- All works has been completed!
- The valve is in the correct position for its function.
- Safety devices have been attached.
ATTENTION !
Refer to item 10.0 and 11.0 before
dismantling the valve.
Fig. 10: V-ring unit
DN15-150