The coalescing filter is a more recent (early 1980s) piece of separation equipment designed for “gas polishing’ service. Fig 7-25 illustrates a typical coalescing filter. A coalescing filter is typically intended to remove fine liquid aerosols/mist from gas streams where entrained liquid loads are low. A typical filtration rating for coalescing filter elements is 0.3 microns absolute. This means that solid spherical particles larger than 0.3 micron are unable to pass through the filter element. Aerosol liquid coalescing performance is not as easily quantifiable and is subject to several factors. A coalescing filters are normally used to protect equipment/processes that are particularly sensitive to contamination. Two of the most common applications are upstream of mole sieve systems and amine contactors. The unit is typically intended to remove carryover from an upstream conventional separator and/or any liquids that may condense from the gas phase due to temperature or pressure reduction. Coalescing filters can experience short filter element life if the gas contains appreciable amounts of solids, e.g. corrosion products.