Abstract: A filter has a channel layer film defining a channel, a boundary layer mounted to at least a portion of the channel layer film and forming a non-adhesive boundary for the channel, and filter media disposed in fluid communication with the channel. The boundary layer typically includes a non-porous or semipermeable film. The filter is configured and arranged to provide for flow of at least a portion of a fluid along the channel and into the filter media. This filter can be used in a device as a filter over a vent in a housing of the device.

Abstract: A filtering apparatus (12) includes a filter cartridge (28) which may be replaced or cleaned and re-used. The filter apparatus also includes a heat exchanger (62) which receives cooling air to cool the exhaust prior to filtering. The cooled exhaust does not pose combustion problems for soot or the filter material in the cartridge (28). In addition to cooling the exhaust, a temperature-sensitive valve (36) opens and closes to prevent excessively hot exhaust gas from reaching the filter cartridge (28). The valve (36) includes bi-metal discs (52) which bow outward when the temperature increases and flatten when the temperature decreases. The discs engage a cover to an orifice and slide axially to open and close the valve (36). The apparatus also may include a back pressure valve (72) which will open when the exhaust flow is backed up to prevent damage to the engine.