Gemu 554 - Troubleshooting Common Valve Faults; Fault Diagnosis and Clearance

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19 Troubleshooting / Fault clearance
Fault Possible cause Fault clearance
Control medium
escapes from vent hole*
(for control function NO)
or from connector 2*
(for control function NC)
Control piston leaking
Replace actuator and check control medium for
impurities
Control medium escapes
from leak detection hole*
Spindle seal leaking
Replace actuator and check control medium for
impurities
Working medium escapes
from leak detection hole*
Gland packing faulty Replace actuator
Valve doesn't open or
doesn't open fully
Control pressure too low
Set control pressure in accordance with data
sheet. Check pilot valve and replace if necessary
Control medium not connected Connect control medium
Control piston or spindle sealing
leaky
Replace actuator and check control medium for
impurities
Actuator spring faulty
(for control function NO)
Replace actuator
Valve leaks downstream
(doesn't close or doesn't
close fully)
Operating pressure too high
Operate valve with operating pressure specified in
data sheet
Foreign matter between seat
seal* and seat
Remove actuator, remove foreign matter, check
seat seal for damage and replace if necessary
(replace actuator for actuator size B)
Valve body leaky or damaged Check valve body and replace if necessary
Seat seal* faulty
Check seat seal for damage and replace if
necessary (replace actuator for actuator size B)
Actuator spring faulty
(for control function NC)
Replace actuator
Valve leaks between
actuator and valve body
Actuator loose
Actuator sizes 0, 0K, 1, 1K, 2, 2K, 3, 3L, 4, 4L:
Tighten the actuator using the union nut*
Actuator size B: Tighten actuator with a pin wrench
(pin size 3 mm)
Gasket* faulty
Check gasket and the respective sealing surfaces
for damage and replace parts if necessary
Valve body / actuator damaged Replace valve body / actuator
Valve body connection to
piping leaks
Incorrect installation Check installation of valve body in piping
Threaded connections / bolting
loose
Tighten threaded connections / bolting
Sealing material faulty Replace sealing material
Valve body leaks Valve body leaks or is corroded
Check valve body for damage, replace valve body
if necessary
* see chapter 20 "Sectional drawing and spare parts"