Dangers of running a centrifugal pump in reverse

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The reversal of water pumps can also be divided into active reversal and passive reversal, with each causing different types of hazards. Active reversal refers to the pump being driven by the motor in the reverse direction, which is mainly caused by reversed motor wiring. The main hazards are: First, mechanical seals that require a specific rotation direction may be damaged. II. Shaft sleeve lock nuts and impeller locking nuts (also known as impeller coupling nuts) that require a specific rotation direction may loosen. If pins are used for connection, the impact will not be significant. Passive reversal refers to the pump driving the motor to reverse direction. The liquid in the pump’s outlet pipeline flows back into the inlet, causing the pump to rotate in reverse, which in turn causes the motor to rotate in reverse (at this point, it is also necessary to consider whether the motor has lost power). The main hazards are: First, mechanical seals that require a specific rotation direction may be damaged. II. Shaft sleeve lock nuts and impeller locking nuts (also known as impeller coupling nuts) that require a specific rotation direction may loosen. If pins are used for connection, the impact will not be significant. III. Pumps with balance discs or balance drums may damage the balance discs or balance drums. IV. It causes water hammer, damaging the pump structure. V. Multi-stage centrifugal pumps (with guide vanes) are prone to reaching resonance speeds, which can damage the pump equipment. (Axial flow pumps require consideration of the pump’s runaway speed.) The harm to the motor mainly lies in the possibility of burning out or damaging electrical components, as well as potential damage to the motor shaft and bearings; the extent of the damage varies. Attention should be paid to the connection method between motors and pumps on the China Pump Industry Network. Depending on the connection method, the degree of damage caused to the motor by pump reversal varies as well.