GF DIASTAR 025 Manuel D'utilisation page 28

Pneumatic diaphragm valve DIASTAR 025
8 Troubleshooting
Malfunction
Leakage to the outside at flange connec-
tion
Leakage to the outside at union nut
Leakage between valve body and housing
nut connection
Seat leakage/through hole leakage
Leakage of control medium from
unconnected air connection
Leakage of the control medium at vent
outlet
Fitting does not perform the specified
stroke or does not close or open
Diaphragm valve does not open comple-
tely
Diaphragm valve does not close comple-
tely
Valve actuation sluggish
Pipe and/or diaphragm valve deform or
expand
Premature wear of the diaphragm valve
or individual parts
28
Possible Cause
Temperature change
Gasket defective
Loose connection of union nut and valve
body
Gasket defective
Housing nut not tightened correctly
Diaphragm wear
Valve body defective
Diaphragm not correctly installed/
aligned
Diaphragm wear
Gasket wear
Wear of the gaskets and diaphragms
Incorrect control pressure level selected
Function and connections for control
medium do not match
Defective aeration and venting line
Diaphragm not correctly installed/
aligned
Pressure in the piping system too high
Foreign body between diaphragm and
valve body
Components defective
Wear of the spindle or gaskets
Pipe forces are too high
Material are not sufficiently resistant
Medium is contaminated
Operating Instructions
Troubleshooting
► Tighten connection and replace
gasket if necessary.
► Replace gasket.
► Tighten the connection hand-tight.
► Replace gasket.
► Tighten the upper part of the
housing.
► Replace diaphragm.
► Check valve body for damage and
replace if necessary.
► Check that the diaphragm is
correctly installed.
► Replace diaphragm.
► Change spindle and piston gaskets.
► Change spindle and piston gaskets.
► Check the control pressure.
► Check the (FC, FO, DA) functions and
related connections.
► Check that the aeration and deaerati-
on line work.
► Check that the diaphragm is
correctly installed.
► Valve operated only within the
specified data.
► Remove foreign bodies and check
valve body and diaphragm for
damage.
► Check valve body and diaphragm for
damage and replace if necessary.
► Replace gaskets and, if necessary,
functional parts.
► Improve support of the pipe.
► Select suitable materials, see Georg
Fischer Planning Fundamentals
Industry.
► Check/clean medium for contamina-
tion.