End of service life indicator for fluid filter

摘要

An end of service life indicator (ESLI) device for a fluid filter is included on the filter and visually indicates when the life of the filter has expired. The ESLI indicates the depletion of the filter by changing the color density on a surface of the device to a color density having a well distinguishable contrasting pattern that is easily recognizable even by individuals who are color-blind. The contrasting pattern may express text indicative of the state of the filter.