What is the function of the coalescer bag in the water separator?

The function of the coalescer bag in a water separator is primarily to absorb moisture from the air. Coalescers are designed to facilitate the removal of water droplets from air or fuel by allowing smaller droplets to merge into larger ones, effectively separating them from the flow. In an aviation context, this is crucial because excessive moisture can lead to problems such as corrosion, reduced fuel efficiency, and operational safety hazards.

By using the coalescer bag, the system ensures that the air (or fuel) that is processed is free of water, which helps to maintain the integrity of the engines and other components by preventing issues related to water contamination. This makes the functionality of the coalescer bag essential in maintaining the overall performance and safety of aircraft operations.