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Symptom
Not enough capacity Viscosity too low
Pump too noisy
Pump consumes
too much power or
becomes hot
Rapid wear
Motor overloading
Pump leak
Rapid wear of the
mechanical seal
Note! If symptoms persist, the pump must be taken out of service immediately. Contact your local supplier.
A.0500.751 – IM-TGBLOC/01.00 EN (10/2020)
Cause
Axial clearance
Gases come free
Pump speed too high
Cavitation
Back pressure too high
Vibration of pipings
Ball bearings damaged or worn
Pump speed too high
Viscosity too high
Back pressure too high
Solid matter in liquid
Pump runs dry
Corrosion
Back pressure too high
Viscosity too high
Mechanical seal leaks
Viscosity too high
Bad de-aerating/ dry running
Temperature too high
Too long priming period/ dry running
Liquid is abrasive
Remedy
17 • Increase pump speed. Attention! Do not exceed
maximum speed and check NPSHr.
• If necessary, install a larger pump.
• If pump is heated by means of heating jackets or
electrical heating, reduce the heating input.
18 • Check axial clearance and correct.
See section 3.20 Maintenance instructions.
19 • Increase pump speed. Attention! Do not exceed
maximum speed and check NPSHr.
• Install a larger pump
20 • Reduce pump speed.
If necessary, install a larger pump.
21 • Reduce difference between pump and suction
tank level.
• Increase suction pipe diameter.
• Reduce length and simplify suction pipe (use as
few elbows and other fittings as possible).
Also see section 3.17 Installation.
22 • Increase pipe diameter.
• Reduce working pressure.
• Check accessories (filter, heat exchanger, etc.).
23 • Make pipework better.
24 • Replace ball bearings.
25 • Reduce pump speed.
If necessary, install a larger pump.
26 • Increase axial clearance.
See section 3.20 Maintenance instructions.
• Heat pump.
• Reduce pump speed.
• Increase discharge pipe diameter.
27 • Increase pipe diameter.
• Reduce working pressure.
• Check accessories (filter, heat exchanger, etc.)
28 • Filter liquid.
29 • Correct liquid supply.
• Provide level switch or dry running protection.
• Heat up liquid.
• Stop or reduce air sucking.
30 • Change pump materials or application
parameters.
31 • Increase pipe diameter.
• Reduce working pressure.
• Check accessories (filter, heat exchanger, etc.).
32 • Increase axial clearance.
See section 3.20 Maintenance instructions.
• Heat pump.
• Reduce pump speed.
• Increase discharge pipe diameter.
33 • Replace mechanical seal.
34 • Heat the pump.
35 • Fill pump with liquid
• Check position of relief valve or top cover.
36 • Reduce temperature.
• Install suitable mechanical seal.
37 • Reduce suction line.
• Provide dry running protection.
• Check maximum allowable dry running speed for
the mechanical seal.
38 • Filter or neutralise liquid.
39
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