On the previous pages about compressed air filters, we identified the parts of the filter and discussed their use.
The items identified in the image below are discussed on earlier pages, except for item 4. This is the compressed air filter baffle.

Item four in the image is the compressed air filter baffle. It’s purpose? To provide a wall between the turbulence of the compressed air is at flows into the filter and the depositary of water and other debris that collects in the bottom of the filter bowl.
Without the filter baffle, since the compressed air is moving at around the speed of sound, water and debris in the bottom of the filter bowl would be agitated by the moving air, re-entrained into the moving air, and blasted onto the surface of the filter element, which would lead to rapid plugging of that element.
There is a small gap between the edge of the compressed air filter baffle and the surrounding filter bowl. This allows water and debris that has been flung out of the air onto the bowl to drip down, below the baffle, and into the quiet zone of the filter.

You want a compressed air filter!
Those folks that use compressed air sparingly, the odd blow off of a work bench or to inflate a bike tire, you may be able to get away without using a compressed air filter because any water entrained in the air from your compressor won’t do much harm in these uses.
If you use your compressor a lot however, and particularly if you are using vane-type air tools, water in the air line will enter the tool, wash out any factory lube, and may rust tool components.
Debris coming down the air line and entering the air tools will affect the air tool seal life.
All compressed air has water content, in vapor or liquid form. The more air you use the higher the water content in the air stream, and that water content gets even higher as the compressor, and the air in the tank, gets hot from longer term compressor use.
A compressed air filter placed in the supply line just before the air tool will strip most of the free water from the air supply, remove most air borne debris from the tool air supply, and will reduce the maintenance cycle and increase the life expectancy of the air tool now that the air supply is clean and dry.
That’s why you want a compressed air filter in your compressed air supply.