The bottom of the filter is a hollow water collector. (See Figure 4-19). Because of the greater density of the water, the water droplets will separate from the fuel oil. It will hold approximately 260 cubic centimeters of water (approx. 3-10%).
A nylon fiberglass coalescent is used to blend the small water droplets into larger ones.
“One micron” water droplets collect in the coalescent fibers, and when the droplets get large and heavy enough they drop into the filter bottom.
The coalescing increases the water concentration from 20-30 ppm to 100 ppm. This allows for more efficient water collection.