If item "1" in the illustrated oily water separator indicates an abnormally deep vacuum, which of the following conditions is the most probable cause? GS-0153

Correct Answer: Option B — Suction line inlet strainer is obstructed.

An abnormally deep vacuum on the suction side of an oily-water separator indicates a restriction in the flow path before the gauge. An obstructed suction line inlet strainer prevents the pump from drawing sufficient fluid, causing the pump to pull a vacuum against the blockage, significantly increasing the negative pressure.