Question 147General Subjects - 1st Asst/Chief

The correct answer is B) The oil discharge check valve fails to open, and as a result no oil actually discharges. This is the correct answer because if the oil discharge check valve fails to open, it would prevent the oil from being discharged from the oily-water separator, even though the system is in the oil discharge mode. This would result in the oil backing up and exiting the upper sampling valve under positive pressure, as described in the scenario. The other answer choices are incorrect because: A) the clean water supply solenoid failing to open would not cause the oil to exit under positive pressure; C) the lower oil/water interface detection probe failing would not prevent the oil discharge mode from being initiated; and D) the upper oil/water interface detection probe failing would not cause the oil to continue discharging, but rather would fail to end the oil discharge mode.