Foreign articles trap

Claim 1

A TRAP FOR FOREIGN ARTICLES IN A LIQUID FLOW PASSAGE, COMPRISING: A RECEPTACLE FORMING A PART OF SAID PASSAGE; A REMOVABLE CUP IN SAID RECEPTACLE HAVING SPACED INNER AND OUTER WALLS OPEN AT THE TOP AND JOINED AT THE BOTTOM, SAID INNER WALL ENCLOSING A SPACE UPON AT THE TOP AND BOTTOM TO FORM AN INNER PASSAGE; AND A REMOVABLE COVER EXTENDING ACROSS SAID TOP OF SAID INNER WALL BUT SPACED THEREFROM, SAID COVER HAVING A DEPENDING PERIPHERAL FLANGE EXTENDING DOWNWARDLY BETWEEN SAID INNER AND OUTER WALLS, SAID CUP AND COVER THEREBY FORMING A LIQUID PASSAGE EXTENDING DOWNWARDLY BETWEEN SAID OUTER WALL AND SAID FLANGE, UPWARDLY BETWEEN SAID FLANGE AND SAID INNER WALL AND DOWNWARDLY THROUGH SAID INNER PASSAGE, SAID INNER WALL AND SAID COVER FLANGE BEING CORRUGATED TO DEFINE A FLOW PASSAGE OF UNDULATING TRANSVERSE CROSS SECTION.