- Delivery liquid too viscous.
- Separation of crystals from the flow of pumping liquid
- Packing incorrectly fitted.
- Gland tightened too much/slanted.
- Axial thrust too great because of worn casing rings, relief holes obstructed.
- Alignment of coupling taulty or coupling loose.
- Rotor parts touching the casing.
- Delivery flow too great.
- Pump unsuitable for parallel operation.
- Type of pump unsuitable.
- Incorrect choice of pump for existing operating conditions.
- Voltage too low/power supply overloaded.
- Short circuit in the motor.
- Setting of starter of motor too high.