Abstract: Constructions and methods are described for collecting particulate material from gas streams. In certain specifically described air filter arrangements, a first, rigid, filter construction is used in conjunction with a removable and replaceable depth media filter, to form filter media. The preferred arrangement is configured so that the removable and replaceable depth media filter can be removed and replaced, without disengaging the first filter construction from a filter assembly or housing, if desired. Some preferred configurations and materials are described.

Abstract: Constructions and methods are described for collecting particulate material from gas streams. In certain specifically described air filter arrangements, a first, rigid, filter construction is used in conjunction with a removable and replaceable depth media filter, to form filter media. The preferred arrangement is configured so that the removable and replaceable depth media filter can be removed and replaced, without disengaging the first filter construction from a filter assembly or housing, if desired. Some preferred configurations and materials are described.

Abstract: Constructions and methods are described for collecting particulate material from gas streams. In certain specifically described air filter arrangements, a first, rigid, filter construction is used in conjunction with a removable and replaceable depth media filter, to form filter media. The preferred arrangement is configured so that the removable and replaceable depth media filter can be removed and replaced, without disengaging the first filter construction from a filter assembly or housing, if desired. Some preferred configurations and materials are described.

Abstract: Trap muffler apparatus with bypass around a trap core is disclosed. A preferred bypass arrangement utilizing a tubular shutter valve system is described. Forward or reverse regeneration are possible. Bypass to atmosphere without filtration is avoided with dual in-line traps or with the segmented trap and control of exhaust gases to traps not being regenerated.

Abstract: Trap muffler apparatus with bypass to a common reactive acoustic element is disclosed. Bypass structure varies from external bypass to a common acoustic element to annular bypass of the ceramic filter to axial bypass through the middle of an annular ceramic filter. Forward or reverse regeneration are possible. Bypass to atmosphere without filtration is avoided with dual in-line traps or with the segmented trap and control of exhaust gases to traps not being regenerated.

Abstract: A device for monitoring the condition of a filter element, comprising a combined clamping nut and differential pressure indicator. The body of the device is non-circular about an axis to facilitate its use as a wingnut, and has an outer surface and an inner surface through which passes an axial orifice, internally threaded to engage a threaded mounting rod. A differential pressure responsive device of novel design, including a slack diaphragm and an air-permeable translucent screen, is mounted in a further orifice in the outer surface for exposure of one side of the diaphragm to the pressure outside the filter, and a passage in the body connects the further aperture with the inner surface to supply to the other side of the pressure responsive device the pressure within the filter. The combination of such an arrangement with an air cleaner having a safety filter is also a part of the invention, as is the method of monitoring the filter conditions which the structure makes possible.