ARI Armaturen STEVI BBD 415 DN 25-50 EN - Manual (Page 15)

Rev. 0040321000 0714 Page 2-15
Operating and Installation Instructions
Straight-through blow-down valves - STEVI
®
BBD 415
9.0 Troubleshooting table
ATTENTION !
- Read sections 10.0 and 11.0 prior to all dismantling or repair work!
- Read section 6.0 before restarting the plant!
Fault Possible cause Corrective measure
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).
Piping system clogged. Check piping system.
Valve stem moves in jerks Stuffing box seal too tight (valves with
graphite packing).
Slacken screw joint (pos. 29) slightly;
valve must not begin to leak.
Valve stem leaking PTFE V-ring unit damaged or worn. Replace seal pack (pos. 12);
refer to section 7.1.1.
Screw joint (pos. 29) is not tight (valves
with stuffing box packing). Tighten screw joint (pos. 29) and
replace packing if necessary.
Leakage too high when
valve closed Sealing surfaces of plug eroded or
worn. Replace plug;
refer to section 7.2.
Sealing edge of seating damaged or
worn. Grind seat.
Seating and/or plug dirty. Clean valve trim.
Pneumatic actuator not completely
vented; spring force not fully effective. Vent actuator air chamber completely.
Actuator not powerful enough. Install more powerful actuator.
Actuator unit does not
move No compressed air on control pressure
line. Identify causes and take remedial
action.
Actuator unit incorrectly installed. Check actuator mode of operation and
connect to control pressure line
accordingly.
Rolling diaphragm defective. Replace rolling diaphragm and springs.
Not enough positioning
force Stem seal is leaking. Replace stem seal.
Vent is clogged and air cannot escape
from actuator. Screw plug must be unclogged.
Actuator not completely vented. Check controller adjustment.