Apparatus for measuring dust particles

Claim 1

APPARATUS FOR SEPARATING DUST PARTICLES OF SIZE BETWEEN PREDETERMINED UPPER AND LOWER LIMITS FROM AN AIR STREAM COMPRISING COAXIALLY DISPOSED DRUM AND CORE MEMBERS MOUNTED FOR ROTATION ABOUT THEIR AXES, SAID DRUM MEMBER HAVING INLET AND OUTLET OPENINGS IN ITS ENDS, SAID INLET OPENING BEING COAXIAL WITH THE DRUM, A DISC-SHAPED MEMBER DISPOSED OUTSIDE THE DRUM ADJACENT TO THE INLT END WALL THEREOF, A PORTION OF SAID CORE EXTENDING THROUGH SAID INLET OPENING IN SAID DRUM END WALL TO DEFINE THEREWITH AN ANNULAR INLET FOR THE DRUM AND EXTENDING INTO THE DRUM IN SPACED RELATION TO THE DRUM SIDE WALL TO DEFINE THEREWITH AN ANNULAR PASSAGE EXTENDING FROM SAID ANNULAR INLET TOWARD THE OTHER END OF THE DRUM, SAID DISC-SHAPED MEMBER BEING COAXIAL WITH THE INLET OPENING AND HAVING ITS ADJACENT END FACE EXTENDING SUBSTANTIALLY PERPENDICULAR TO THE DRUM AXIS IN SPACED RELATION WITH SAID DRUM END WALL TO DEFINE AN ANNULAR CLEARANCE THEREWITH COMMUNICATING WITH SAID ANNULAR INLET, SAID CLEARANCE HAVING SUCH AN AXIAL WIDTH THAT VOTATION OF THE MEMBERS AT A PREDETERMINED SPEED CAUSES AIR PASSING THERETHROUGH TO ROTATE BEFORE ENTERING THE INLET THEREBY DISCHARGING PARTICLES OF SIZE LARGER THAN SAID UPPER LIMIT, AND MEANS FOR INDUCING A FLOW OF AIR INTO SAID INLET OPENING.