DISA Filters Type FS and FD The FS and FD cassette-type filters are modular designed collectors suitable for air-flow volumes up to 1,000,000 m3/h. They are available with “off line” reverse air cleaning sys-tem FS) and “on line” jet pulse cleaning system (FD). Its down-flow design in which dust and transport gas travel in the same direction, results in high efficiency filtration and cleaning. It is well known for applications in metals, asphalt and other industries involving hot gases. The filter is quick to install and the compact design makes it easy to integrate into existing plants and buildings. Energy consumption is reduced to a minimum, whilst the horizontal arrangement of the filter elements facilitates maintenance of the unit.