Abstract: An indicator suitable for signaling restricted flow of a fluid through a filter mounted in a filter indicator includes a housing having an inner cavity. A diaphragm disposed within the housing separates the inner cavity into first and second chambers and deflects from a neutral position in response to applied pressures within the first and second chambers. A tab assembly opposite the diaphragm includes a spring-loaded flag moveable from a first position within the housing to a second position outside the housing. A pin operably coupled to the diaphragm holds the spring-loaded flag within the housing when the diaphragm is in the neutral position. In response to the diaphragm being deflected sufficiently from the neutral position to release the pin, the spring-loaded flag travels to the second position outside of the housing, thereby indicating a restrictive flow condition for the filter.

Abstract: An indicator suitable for signaling restricted flow of a fluid through a filter mounted in a filter assembly includes a housing having an inner cavity. A diaphragm disposed within the housing separates the inner cavity into first and second chambers and deflects from a neutral position in response to applied pressures within the first and second chambers. A tab assembly opposite the diaphragm includes a spring-loaded flag moveable from a first position within the housing to a second position outside the housing. A pin operably coupled to the diaphragm holds the spring-loaded flag within the housing when the diaphragm is in the neutral position. In response to the diaphragm being deflected sufficiently from the neutral position to release the pin, the spring-loaded flag travels to the second position outside the housing, thereby indicating a restricted flow condition for the filter.

Abstract: A low cost air filter restriction indicator gauge for use in conjunction with an internal combustion engine can be achieved by both simplifying individual part configuration and reducing overall part count. More specifically, a simplified design can be achieved by utilizing a one piece base cap which includes a locking extension and reset button integral therewith. By having this part injection moldable, it is easy to fabricate and lower in cost as a complex locking pin assembly can be eliminated. Further, the low cost device can be further enhanced by providing a two color visual indicator which displays one color when the device is in its reset position and a second color when the device is in its locked or set position.

Abstract: An air restriction indicating device for measuring very low ranges of filter restriction (e.g., on the order of 0.0 to 1.5 inches of H.sub.2 O or 0.0 to 0.54 psi) in a micronfilter used in vehicular heating/ventilation/air conditioning (HVAC) systems. The indicating device includes a housing that is separated into two sub-chambers by a flexible diaphragm. A indicating member is carried by the diaphragm so that the diaphragm and the indicating member move, within the housing, responsively to changes in the pressure of the air flowing in the HVAC system caused by restrictions in or clogging of the micronfilter. To facilitate reading, the indicating device also includes structure that progressively locks the diaphragm and indicating member in position.

Abstract: An indicating device includes a housing that is separated into two sub-chambers by a flexible diaphragm. A indicating member is carried by the diaphragm so that the diaphragm and the indicating member move, within the housing, responsively to changes in the pressure of the air flowing through an air intake system caused by restrictions in or clogging of the air intake filter. The indicating device incorporates an electromechanical sensor for monitoring the position of the diaphragm and producing an output signal responsive thereto. In one embodiment, the sensor is a potentiometer which produces an output signal which varies continuously between a first value when the diaphragm is at its unrestricted position and a second value when the diaphragm is at its restricted position. In a second embodiment, the sensor includes a switching circuit which produces a switched output signal which varies between at least three states corresponding to three different diaphragm positions.