Coalescer Elements were used in 1. stages of filter water separators. Their main function is coalesing of small water droplets to big droplets. These big water droplets are drop to the watersump of the filter water separator because higher weights. Furthermore they holding back particles like sand, rust and other soiling. 

Elements type Application
P -Type EI 1581, 5th Ed., Cat. C
MIL -Type EI 1581, 5th Ed., Cat. M  
Y -Type EI 1581, 5th Ed., Cat. M; TL 4330-0001, Part 3
K- type EI 1581, 3rd Ed., Gr. II, Class A, B & C; MIL-F-8901E
D -Type  TL 4330-0001, Part 2; MIL-F-8901E, AM+M 537B
A -Type for diesel, gasoline, etc.
DC -Type   for diesel, gasoline, etc.
FDC -Type for diesel applications
FDC -2-Type for diesel applications (2" Outer Diameter)