An air pollution control device normally using a collection of long, cylindrical, fabric filters to remove particulate matter from an exhaust air stream. The filter arrangement is normally designed to overcome problems of cleaning and handling large exhaust volumes. In most cases, exhaust gas enters long (usually 33–50 ft [10–15 m]), vertical, cylindrical filters on the inside from the bottom. The bags are sealed at the top. As the exhaust air passes through the fabric filter, particles are separated from the air stream by sticking either to the filter fabric or to the cake of particles previously collected on the inside of the filter. The exhaust then passes to the atmosphere free of most of its original particulate-matter loading; collection efficiency usually increases with particle size.

Baghouse. (McGraw-Hill Inc. Reproduced by permission.)

The buildup of particles on the inside of the bags is removed periodically by various methods, such as rapping the bags, pulsing the air flow through the bags, or shaking. The particles fall down the long cylindrical bags and are normally caught in a collection bin, which is unloaded periodically. A baghouse system is usually much cheaper to install and operate than a system using electrostatic precipitation to remove particulates.