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5.2 Fault Finding
Listed below is a guide to commonly asked questions regarding filter performance.
F
AULT
P
OSSIBLE
C
AUSE
R
EMEDY
Excessive Backwash
Frequency
Filter elements blocked or
excessively fouled.
DP switch set too low.
Flow rate has increased.
Contamination has
increased.
Backwash interval timer
too low.
Clean and replace filter elements, see Section 4.1 and
4.2.
Raise DP switch set point, see Section 2.1
Check and regulate.
Check, and if possible, increase DP switch set point. If
contamination load cannot be corrected, coarser
elements may be required.
Reset, see Section 2.3.
Continuous
Backwash
See Excessive Backwash
Frequency faults and
remedies.
DP switch has failed.
Verify by removing the DP switch’s electrical cover and
check that contacts are being switched on rise and fall
of DP. Replace switch if necessary.
Upon completion of
backwash, DP is
higher than clean DP
Filter elements blocked or
excessively fouled.
System pressure too low
for effective backwash.
Backwash duration set too
low to give thorough clean.
DP switch set point set too
high causing excessive
blinding of elements.
Clean and replace filter elements, see Section 4.1 and
4.2.
Check and regulate.
Increase backwash duration time setting, see Section
2.2.
Check and regulate, see Section 2.1
Fluid flows from
backwash line after
end of backwash
cycle
Backwash valve is failing
to close or seat properly
Check that compressed air is reaching the valve and
actuator is working correctly.
If valve is still passing, dismantle and check for an
object jamming the ball valve or damaged seats. Call
supplier for service kit or replacement.
Filter Leaking
“O” seals failed, worn, or
missing.
Check and replace as necessary. See Spare Parts
List, Section 6.0, for part numbers.