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The performance of pump seals is critical to ensure reliable protection of submersible wastewater pump motors.

 

Neglecting regular inspection of pumps, including pump seals, can lead to leaks and premature motor failure.

 

Seal leak detectors can identify a leaking seal before the leak can damage the motor.

 

Seal leak detectors are placed between the two seals of a double mechanical seal pump. The double seal is packed in a dielectric oil filled chamber with both ends of the assembly sealing the chamber along with a probe whose case is grounded to the frame of the volute.

 

The seal leak detector cord is a two-wire circuit which detects the presence of water in the oil filled cavity of a double seal system. To utilize this feature, the control panel must have a seal leak detector circuit.

 

When moisture is detected by contact with water entering the seal chamber, it shorts to the grounded volute and the alarm is activated in the panel. Depending on the panel, either one or two terminals will be marked for this circuit. If there are two terminals, then the two conductors in the cord will be placed on those terminals. If only one terminal is present, the black conductor will go to that terminal and the other to the panel ground lug. Depending on the panel manufacturer and schematic, the alarm light may activate when powered up. If this happens, reverse the conductors so that the green wire is on the grounded terminal. The alarm should deactivate.

 

If the panel does not have a seal leak circuit, the conductors may be terminated at the panel and a service tech can check the seals occasionally by connecting an ohm meter to the black and green wire. As the moisture in the seal cavity increases, the ohm readings will decrease towards 0 ohms indicating a seal leak.

 

By detecting early seal leakage, a repair can be made while the upper seal is still intact with the motor chamber. Replacing the seal and the dielectric oil is a relatively simple process. This will keep the motor operating in a clean environment and will provide longer service. For information on changing seals, visit our YouTube channel for videos on making this type of repair.