GEM 658, Installation, Operating And Maintenance Instructions, Page: 37 / 44

19 Troubleshooting / Fault clearance
Fault Possible cause Fault clearance
Control medium escapes from
one actuator vent hole*
Lip ring faulty Replace actuator
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*
Valve diaphragm faulty
Check valve diaphragm for damage,
replace diaphragm if necessary
Valve doesn't open or doesn't
open fully
Control pressure too low
Operate valve with control pressure
specified in data sheet
Pilot valve faulty Check and replace pilot valve
Control medium not connected Connect control medium
Valve diaphragm incorrectly mounted
Remove actuator, check diaphragm
mounting, replace if necessary
Stroke limiter incorrectly adjusted Adjust stroke limiter correctly
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 valve diaphragm
and valve body weir
Remove actuator, remove foreign matter,
check valve diaphragm and valve
body weir for damage and replace if
necessary
Valve body weir leaking or damaged
Check valve body weir for damage,
if necessary replace valve body
Valve diaphragm faulty
Check valve diaphragm for damage,
replace diaphragm if necessary
Actuator spring faulty Replace actuator
Valve leaks between actuator
and valve body
Valve diaphragm incorrectly mounted
Remove actuator, check diaphragm
mounting, replace if necessary
Bolting between valve body and actuator
loose
Retighten bolting between valve body
and actuator
Valve diaphragm faulty
Check valve diaphragm for damage,
replace diaphragm if necessary
Actuator / valve body damaged Replace actuator / valve body
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 faulty or corroded
Check valve body for damage, replace
valve body if necessary
Proximity switch continuously
responds
Wrong proximity switches used
Only use proximity switches that can be
mounted flush
For diaphragm sizes 40 and 50 use
proximity switches with a minimum
thread length of 35 mm
* see chapter 20 "Sectional drawings and spare parts"
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