Which of the following problems will occur if a manually cleaned disk-type centrifugal lube oil purifier contains insufficient sealing water prior to admitting oil flow to the bowl?

Correct Answer: Option A — Lube oil will discharge from the heavy phase discharge port to the sludge tank.

Insufficient sealing water in a manual disk-type purifier fails to establish the required liquid seal in the peripheral zone. Without this hydraulic barrier, incoming oil overcomes the water seal and prematurely discharges through the heavy phase sludge port instead of clearing the disc stack.