Abstract: A self-cleaning centrifuge for clarifying contaminated liquids has a rotor assembly comprising nested first and second sets of concentric cylinders supported for rotation about an axis. The sets of concentric cylinders are rotatably connected. A motor is connected to rotate one of the sets. Contaminated liquid is supplied to the nested cylinders, and the liquid provides coupling between both of the sets so that both sets rotate about the axis. Centrifugal force causes foreign matter to collect on the circumferential surfaces of the cylinders. The resultant clarified liquid is collected for reuse. A selectively utilized brake provides sudden braking of one of the rotating sets to purge collected foreign matter from the cylinders. The purged foreign matter is collected for disposal.

Abstract: A self-cleaning centrifuge for clarifying contaminated liquids has a rotor assembly comprising nested first and second sets of concentric cylinders supported for rotation about an axis. The sets of concentric cylinders are rotatably connected. A motor means is connected to rotate one of the sets. Means supply contaminated liquid to the nested cylinders, and the liquid provides coupling between both of the sets so that both sets rotate about the axis. Centrifugal force causes foreign matter to collect on the circumferential surfaces of the cylinders. The resultant clarified liquid is collected for reuse. Selectively utilized brake means provides sudden braking of one of the rotating sets to purge collected foreign matter from the cylinders. The purged foreign matter is collected for disposal.

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.