Induced Draft Fans are used in power plants. It exhausts combustion products from a boiler. It creates sufficient negative pressure to establish a slight suction in the furnace. This condition gives rise to the name suction firing or balanced-draft operation. These fans must have enough capacity to accommodate any infiltration caused by the negative pressure in the equipment of ductwork downstream of the furnace and by any seal leakage in air pre-heaters. ID fans are typically located downstream of any particulate removal system, they are a relatively clean service fan. The ID fan is sometimes used as a booster fan with flue gas desulphurization scrubbers. It follows the precipitator or fabric filter and another set of fans-the booster fans-follows the scrubber.