Faults, Causes And Remedies - Wilo -SCP Einbau- Und Betriebsanleitung

10 Faults, causes and remedies

Symptoms
-- Pump does not deliver water.
-- Insufficient capacity delivered.
-- Insufficient pressure developed
-- Pump loses prime after starting.
-- Pump requires excessive power.
-- Stuffing box leaks excessively.
-- Pump vibrates or it is noisy.
-- Bearings have short life.
-- Pump overheats and seizes.
Causes
1 Pump not primed
2 Pump or suction pipe not completely filled with
liquid
3 Suction lift too high.
4 Insufficient margin between pressure and vapor
pressure.
5 Excessive amount of air in liquid.
6 Air pocket in suction line.
7 Air leaks into suction line
8 Air leaks into pump through stuffing boxes.
9 Foot valve too small or leaking.
10 Foot valve partially clogged.
11 Inlet of suction pipe insufficiently submerged.
12 Water seal pipe clogged.
13 Logging ring is improperly located in stuffing
box, preventing sealing fluid from entering to
form seal.
14 Speed too low.
15 Speed too high.
16 Direction of rotating wrong.
17 Total head of system higher than design head of
pump.
18 Total head of system lower than pump design
head.
19 Specific gravity of liquid different from design.
20 Viscosity of liquid different from design.
21 0peration at very low capacity.
22 Parallel operation of pumps unsuitable for such
operation.
23 Foreign matter in impeller.
24 Misalignment.
25 Foundations not rigid.
26 Shaft bent.
Installation and operating instructions Wilo-SCP
Possible cause of trouble and remedies
(Each number is defined in the table below)
1,2,3,4,6,11,14,16,17,22,23
2,3,4,5,6,7,8,9,10.11.14.17,20,22,23.29,30,31
5,14,16,17,20,22,29,30,31
2,3,5,6,7,8,11,12,13
15,16,17,18,19,20,23,24.26,27,29,33,34,37
12,13,24,26,32,33,34,35,36,38.39,40
2,3,4,9,10,11,21.23,24,25.26.27,28,30,35,41,42,43, 44,
45,46,47
24,26,27,28,35,36,41,42,43,44,45,46,47
1,4,21,22,24.27,28,35,36,41
Remedies
Ensure that casing is fully filled and water comes out from air-
cock.
Check leaking foot valve in case of negative suction
Reduce by lowering pump elevation or increase Water level.
Check that NPSH available is at least 1 meter more 1 meter
more than NPSH required.
Check the reasons and eliminate. Gas gets entrapped in liquid.
Air may be entering through suction joints.
Ensure pipe fully filled and there is nobend for negative suction.
Tighten pipe joints with solution.
Ensure stuffing box sealing.
Replace I Attend.
Clean
Ensure adequate submergence such that foot valve is not
exposed.
Clean or change.
Position logging ring centrally under sealing holes of stuffing
box.
Check motor RPM, supply frequency, Motor nameplate speed
should be as specified on pump nameplate.
Check motor RPM and supply frequency.
Check correct direction of rotation for motor before coupling to
motor.
Check the causes and refer to Wilo. Measure with pressure
gauge.
Check the causes and refer to Wilo. Measure with pressure
gauge.
Refer to Wilo.
Refer to Wilo
Check the causes and refer to Wilo, Operate pump at rated
duty.
Refer to Wilo with characteristics curves of pump.
Open and clean.
Check with Dial gauge should be within limits and without
undue pipe stresses.
Check, vibration on Baseplate, check hollowness.
Dismantle and check, Replace shaft.
English
75