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10 Faults, causes and remedies (For Bare Pump Only)
Symptoms
Possible cause of trouble and remedies
(Each number is defined in the table below)
--
Pump does not deliver water.
1,2,3,4,6,11,14,16,17,22,23
--
Insufficient capacity delivered.
2,3,4,5,6,7,8,9,10.11.14.17,20,22,23.29,30,31
--
Insufficient pressure developed
5,14,16,17,20,22,29,30,31
--
Pump loses prime after starting.
2,3,5,6,7,8,11,12,13
--
Pump requires excessive power.
15,16,17,18,19,20,23,24.26,27,29,33,34,37
--
Stuffing box leaks excessively.
12,13,24,26,32,33,34,35,36,38.39,40
--
Pump vibrates or it is noisy.
2,3,4,9,10,11,21.23,24,25.26.27,28,30,35,41,42,43, 44,
45,46,47
--
Bearings have short life.
24,26,27,28,35,36,41,42,43,44,45,46,47
--
Pump overheats and seizes.
1,4,21,22,24.27,28,35,36,41
Causes
Remedies
1
Pump not primed
Ensure that casing is fully filled, and water comes out from air
cock.
2
Pump or suction pipe not completely filled with
Check leaking foot valve in case of negative suction
liquid
3
Suction lift too high.
Reduce by lowering pump elevation or increase Water level.
4
Insufficient margin between pressure and vapor Check that NPSH available is at least 1 meter more 1 meter
pressure.
more than NPSH required.
5
Excessive amount of air in liquid.
Check the reasons and eliminate. Gas gets entrapped in liquid.
Air may be entering through suction joints.
6
Air pocket in suction line.
Ensure pipe fully filled and there is no bend for negative suction.
7
Air leaks into suction line
Tighten pipe joints with solution.
8
Air leaks into pump through stuffing boxes.
Ensure stuffing box sealing.
9
Foot valve too small or leaking.
Replace
I
Attend.
10
Foot valve partially clogged.
Clean
11
Inlet of suction pipe insufficiently submerged.
Ensure adequate submergence such that foot valve is not
exposed.
12
Water seal pipe clogged.
Clean or change.
13
Logging ring is improperly located in stuffing
Position logging ring centrally under sealing holes of stuffing
box, preventing sealing fluid from entering to
box. form Seal.
14
Speed too low.
Check motor RPM, supply frequency, Motor nameplate speed
should be as specified on pump nameplate.
15
Speed too high.
Check motor RPM and supply frequency.
16
Direction of rotating wrong.
Check correct direction of rotation for motor before coupling to
motor.
17
Total head of system higher than design head Check the causes and refer to M&P. Measure with pressure
of pump.
gauge.
18
Total head of system lower than pump design
Check the causes and refer to M&P. Measure with pressure
head.
gauge.
19
Specific gravity of liquid different from design.
Refer to M&P.
20
Viscosity of liquid different from design.
Refer to M&P
21
0peration at very low capacity.
Check the causes and refer to M&P, operate pump at rated
duty.
22
Parallel operation of pumps unsuitable for such Refer to M&P with characteristics curves of pump.
operation.
23
Foreign matter in impeller.
Open and clean.
24
Misalignment.
Check with Dial gauge should be within limits and without
undue pipe stresses.
25
Foundations not rigid.
Check, vibration on Baseplate, check hollowness.
26
Shaft bent.
Dismantle and check, Replace shaft.
Installation and operating instructions WILO-Split Case Pumps
29