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Claim 1

IN COMBINATION WITH A FLUID CIRCUIT CONTAINING A REPLACEABLE FILTER ELEMENT DISPOSED IN A FILTER WITH A INLET AND OUTLET, A DUAL READING FILTER CONDITION INDICATOR CAPABLE OF INDICATING EITHER A CLOGGED OR RUPTURED FILTER ELEMENT COMPRISING: (A) A BODY HAVING A PASSAGE THERETHROUGH, SAID BODY HAVING TRANSPARENT END PORTIONS THROUGH WHICH SAID PASSAGE CAN BE VISUALLY OBSERVED; (B) A PLUNGER MEANS DISPOSED RECIPROCALLY IN SAID PASSAGE AND SEALING PORTIONS OF SAID PASSAGE ON OPPOSITE SIDES OF SAID PLUNGER MEANS FROM ONE ANOTHER; (C) SPRING MEANS SUPPORTED AT ONE END OF SAID BODY WITHIN SAID PASSAGE AND BEARING ON SAID PLUNGER MEANS AND HAVING SUFFICIENT EXTENSION TO PUSH SAID PLUNGER MEANS TO THE OPPOSITE END OF SAID PASSAGE; (D) CONDUIT MEANS CONNECTING THE PORTION OF SAID PASSAGE CONTAINING SAID SPRING MEANS WITH SAID OUTLET OF SAID FILTER; AND (E) SECOND CONDUIT MEANS CONNECTING THE PORTION OF SUCH PASSAGE FREE OF SAID SPRING MEANS WITH SAID INLET OF SAID FILTER WHEREBY A DIFFERENTIAL PRESSURE ACROSS THE FILTER ELEMENT WILL CENTRALLY POSITION SAID PLUNGER IN SAID PASSAGE UNTIL SAID FILTER ELEMENT IS CLOGGED OR RUPTURED WHICH WILL CAUSE SAID PLUNGER MEANS TO MOVE INTO ONE OR THE OTHER WARNING AREAS AT OPPOSITE ENDS OF SAID INDICATOR.