ARI Armaturen STEVI 460 DN 300-500 EN - Manual (Page 14)

Page 14 Rev. 0040304002 0410
Operating and installation instructions
Str. thr. stop valves - STEVI
®
405 / 460 (DN300-500)
9.0 Troubleshooting table
ATTENTION !
- read item 10.0 and 11.0 prior to dismantling and repair work!
- read item 6.0 before restarting the plant !
Fault Possible cause Corrective measures
No flow Valve closed Open valve (using actuator)
Flange covers not removed Remove flange covers
Little flow Valve not sufficiently open Open valve (using actuator)
Dirt sieve clogged Clean / replace sieve
Piping system clogged Check piping system
Valve stem moves in jerks. Stuffing box sealing too tight (for valves
with graphite packings)
Slacken stuffing box gland with nut
(pos. 18 resp. pos. 20.29);
Valve must nor start leaking!
Valve stem leaking. Defective stem sealing in valves with
EPDM stem sealing Replace stem sealing;
refer to item 7.1.1
In valves with packed stuffing boxes,
tighten screw joint (pos. 29/pos. 20.17) Tighten screw joint (pos. 29/
pos. 20.17);
replace packing if necessary;
refer to item 7.1.2
Bellows defective in valves with bellow
seal Replace bellows unit (pos. 20.3);
refer to item 7.1.3
Leakage too high when
valve is closed. Sealing surfaces of plug eroded or worn Replace plug;
refer to item 7.2.2.
Sealing edge of seating damages or
worn Grind the seat
Seating and/or plug dirty. Clean internals of valve
Pneumatic actuator not completely
vented; spring force not fully effective Vent actuator air chamber completely
Actuator not powerful enough Install more powerful actuator