Exam Question

### (a) Sketch of a Two-Stage Oily Water Separator
A simple line diagram as required for the examination should clearly illustrate the key components and the flow path of the fluid. The sketch would depict:
1. **First Stage (Gravity Separator):** A vertical cylindrical vessel with an inlet for the oily water mixture from the bilge holding tank via a dedicated pump (typically a progressive cavity or screw pump to avoid further emulsification). Inside, a series of conical catch plates are shown. An oil collecting dome is located at the top, equipped with an automatic oil discharge valve connected to a slop/sludge tank. A water outlet at the bottom leads to the second stage.
2. **Second Stage (Filter/Coalescer Unit):** A second, typically smaller vessel receiving water from the first stage. It contains two sets of internal elements: a pre-filter for solid particles and the main coalescing filter elements.