Abstract: A display provides an indication of the remaining useful life of a filter element by providing a visible level of fluid in the display corresponding to the remaining useful life. The fluid level is adjusted by a valve responsive to a pressure differential across the filter element. An increasing pressure differential produces an increased fluid level in the display. The display may be provided with markings indicating that a particular fluid level in the display corresponds to the need to change a filter cartridge containing the filter element.

Abstract: A fluid system pressure indicator is adapted for use in fluid systems having a filter element. The fluid system force indicator includes a housing partitioned to be exposed to the fluid system to provide transmission of a mechanical force between these partitioned environments to indicate the fluid pressure. This exterior shape change is such that it can be identified through tactile means not requiring visual identification.

Abstract: A fluid system pressure indicator is adapted for use in fluid systems having a filter element. The fluid system force indicator includes a housing partitioned to be exposed to the fluid system to provide transmission of a mechanical force between these partitioned environments to indicate the fluid pressure. This exterior shape change is such that it can be identified through tactile means not requiring visual identification.

Abstract: A fluid system pressure indicator is adapted for use in fluid systems having a filter element. The fluid system force indicator includes a housing partitioned to be exposed to the fluid system to provide transmission of a mechanical force between these partitioned environments to indicate the fluid pressure. This exterior shape change is such that it can be identified through tactile means not requiring visual identification.

Abstract: A filter assembly employs radially inwardly and outwardly displaced portions of a peripheral roll seam on the cartridge as components of a cartridge compatibility matrix. A substantially annular space, the radial configuration of which varies with the convoluted roll seam, is defined between the roll seam and a cylindrical wall of the cartridge end cap. The base includes an axially projecting receptacle wall that terminates in a coded lip to define a receptacle for receiving the cartridge end cap. The cartridge mounting system requires axial reception of the coded lip into the substantially annular space of the filter cartridge. The coded lip is configured to block reception and mating of any filter cartridge whose roll seam defines a substantially annular space of incompatible radial configuration. The number, configuration and location of inwardly and outwardly displaced portions of the roll seam may be varied to provide a variety of unique compatibility matrices.

Abstract: A filter assembly employs radial interference between the received portion of a filter cartridge housing and the receptacle of a base. Radial interference occurs between a tapered end cap of the filter cartridge and a substantially cylindrical inside surface of the base receptacle. The filter cartridge end cap is tapered such that the interference increases as the cartridge is urged into the receptacle by a retaining collar. The tight fit improves resistance to vibration and shock applied to the filter assembly. Metal to metal contact at the interference points also provides a reliable electrical contact between the base and the cartridge to prevent accumulation static charges in the cartridge.

Abstract: A filter assembly employs inward and outward radially displaced portions of a peripheral shoulder on the cartridge as components of a cartridge compatibility matrix. Alternative base assemblies include mounting structures complementary to the configuration of the peripheral shoulder to exclude incompatible cartridges. The peripheral shoulder is preferably a roll seam connecting first and second sections of the filter housing. The invention further contemplates a pattern of radial protrusions from a portion of the cartridge housing received in a base receptacle as part of a cartridge compatibility matrix. The base receptacle is configured to receive only those cartridges having a compatible pattern of radial protrusions.

Abstract: A filter assembly employs radially inwardly and outwardly displaced portions of a peripheral roll seam on the cartridge as components of a cartridge compatibility matrix. A base defines an axial entrance to a fixed retainer that is complementary to the compatibility matrix of the cartridge roll seam. Axial slots accommodate the outwardly displaced portions of the roll seam while inward protrusions correspond to the location and inward displacement of the inwardly displaced segments of the roll seam. Incompatible filter cartridges are prevented from axial reception into the base. The number, configuration and location of inwardly and outwardly displaced portions of the roll seam may be varied to provide a variety of unique compatibility matrices.

Abstract: A filter cartridge for use with a base to create a filter assembly. The filter cartridge includes a seal to establish a fluid flow within the filter assembly and a resilient bias member to bias the filter cartridge away from the base. The resilient bias member in cooperation with a fastening mechanism secures the filter cartridge to the base.

Abstract: A key track system for a filter base module comprises a ring-shaped fixture including a series of perforations, each perforation at least partially defining a parting line along which a tab may be selectively removed. The key track fixture is incorporated into the filter base module to define the periphery of an entryway to a cartridge-receiving receptacle in the header portion of a base module. In some embodiments, the key track fixture is a molded ring-like component with pre-key selected angularly spaced key slots. Base modules including the key track system may be efficiently configured to accept the key pattern of a filter cartridge compatible with the filter system in which the base module will be used.

Abstract: A filter assembly employs radial interference between the received portion of a filter cartridge housing and the receptacle of a base. Radial interference occurs between a tapered end cap of the filter cartridge and a substantially cylindrical inside surface of the base receptacle. The filter cartridge end cap is tapered such that the interference increases as the cartridge is urged into the receptacle by a retaining collar. The tight fit improves resistance to vibration and shock applied to the filter assembly. Metal to metal contact at the interference points also provides a reliable electrical contact between the base and the cartridge to prevent accumulation static charges in the cartridge.

Abstract: A filter assembly employs inward and outward radially displaced portions of a peripheral shoulder on the cartridge as components of a cartridge compatibility matrix. Alternative base assemblies include mounting structures complementary to the configuration of the peripheral shoulder to exclude incompatible cartridges. The peripheral shoulder is preferably a roll seam connecting first and second sections of the filter housing. The invention further contemplates a pattern of radial protrusions from a portion of the cartridge housing received in a base receptacle as part of a cartridge compatibility matrix. The base receptacle is configured to receive only those cartridges having a compatible pattern of radial protrusions.

Abstract: A filter assembly employs radially inwardly and outwardly displaced portions of a peripheral roll seam on the cartridge as components of a cartridge compatibility matrix. A base defines an axial entrance to a fixed retainer that is complementary to the compatibility matrix of the cartridge roll seam. Axial slots accommodate the outwardly displaced portions of the roll seam while inward protrusions correspond to the location and inward displacement of the inwardly displaced segments of the roll seam. Incompatible filter cartridges are prevented from axial reception into the base. The number, configuration and location of inwardly and outwardly displaced portions of the roll seam may be varied to provide a variety of unique compatibility matrices.

Abstract: A filter assembly employs radially inwardly and outwardly displaced portions of a peripheral roll seam on the cartridge as components of a cartridge compatibility matrix. A substantially annular space, the radial configuration of which varies with the convoluted roll seam, is defined between the roll seam and a cylindrical wall of the cartridge end cap. The base includes an axially projecting receptacle wall that terminates in a coded lip to define a receptacle for receiving the cartridge end cap. The cartridge mounting system requires axial reception of the coded lip into the substantially annular space of the filter cartridge. The coded lip is configured to block reception and mating of any filter cartridge whose roll seam defines a substantially annular space of incompatible radial configuration. The number, configuration and location of inwardly and outwardly displaced portions of the roll seam may be varied to provide a variety of unique compatibility matrices.

Abstract: A fuel filter cartridge assembly employs a two piece housing to house a replaceable filter unit. The filter cartridge assembly incorporates a key system to ensure compatibility of a replacement filter unit for a given cartridge assembly. Keys formed on the filter unit cooperate with keyways formed in the housing to ensure that only filter units having key structures may be used. Each key may have a different angular position, angular dimension and radial projection. By varying the dimensions of the keys and/or the positions and/or the number of keys, a composite compatibility matrix comprising an infinite number of configuration sets are available to differentiate between filter units having differing flow capacities, filter media, disposal options or other characteristics.

Abstract: A molded base module for a filter assembly includes a header portion that defines a receiving cavity for a replaceable cartridge and may include integral inlet and outlet structures for communicating with the received filtered cartridge. The header portion includes an integrally formed retainer having a retaining channel for receiving tabs projecting from the cartridge, thereby retaining the cartridge to the module. The retaining channel is defined by a retaining lip and axially spaced shoulder connected by a side wall. In an illustrated embodiment, the retaining lip includes a plurality of angularly spaced axial slots and the side wall includes ramp-like projections which mate with correspondingly shaped tabs projecting from the cartridge.

Abstract: A fuel filter cartridge assembly employs a two piece housing to house a disposable, incineratable filter unit. The filter unit is constructed to cooperate with the sealing mechanism of the housing to seal the assembled cartridge against a fuel inlet/outlet conduit. Tabs formed on the filter unit end cap cooperate with slots formed in the housing to ensure that only compatible filter units are used.

Abstract: A filter cartridge for use with a base to create a filter assembly. The filter cartridge includes a seal to establish a fluid flow within the filter assembly and a resilient bias member to bias the filter cartridge away from the base. The resilient bias member in cooperation with a fastening mechanism secures the filter cartridge to the base.