Abstract: An electromagnetic actuating mechanism is provided for a centrifugal pump in which a solenoid ring includes a radially inwardly projecting annular seal movable between open and closed positions with respect to a rotary seal which is mounted for rotation with the drive shaft between the expeller and reservoir region of the pump housing. Spring members are engageable with the ring to normally retain the annular seal in the closed position when the pump is not in operation, and a magnetic drive member is selectively energized to initiate movement of the ring in a direction overcoming the biasing elements to shift the ring to an open position when pump operation is initiated. An energizing control circuit is associated with the pump motor to regulate energizing and deenergizing of the drive member.