ARI Armaturen STEVI 460 DN 15-250 EN - Manual (Page 16)

Page 16 Rev. 0040304000 0410
Operating and installation instructions
Straight thr. stop valves - STEVI
®
405 / 460 (DN15-250)
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 screw joint (pos. 29) or hexa-
gon nuts (pos. 35) slightly.
Valve must nor start leaking!
Valve stem leaking. PTFE V-ring unit damaged or worn. Replace ring pack (pos. 12) - refer to
item 7.1.1
In valves with packed stuffing boxes,
tighten screw joint (pos. 29) or hexagon
nuts (pos. 35). Tighten screw joint (pos. 29) or hexa-
gon nuts (pos. 35); replace packing if
necessary; refer to item 7.1.2
Bellows defective in valves with bellow
seal. Replace bellows unit;
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 7.2.1.
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.