Patent ID: 7325465

Claim:
An apparatus for sampling ambient air and removing particulate matter from the sampled ambient air as separate coarse and fine fractions: a separating device connected to an upstream side of an acceleration tube for separating substantially all particulate matter larger than about 10 microns from ambient air and delivering ambient air containing the remaining coarse and fine fractions to a sample receiving end of said acceleration tube; the acceleration tube extending along a central axis and comprising a conical section tapering from the sample receiving end down to an outlet straight cylinder section integral therewith, said outlet straight cylinder section having a constant diameter D 1 and extending from said conical section to an outlet at a first distal end, wherein the sampled ambient air enters the sample receiving end of said acceleration tube at a first flow rate FR 1 ; a collection tube comprising an inlet straight cylinder section axially aligned with said acceleration tube, having a constant diameter D 2 , and extending along said central axis from an inlet at a second distal end to a conical section integral therewith, said conical section tapering from the diameter D 2 to a discharge end of a diameter D 3 , larger than diameter D 2 , wherein the ratio of D 2 /D 1 is >1 to 2 and wherein said first and second distal ends face each other and are spaced apart by a distance d, wherein the ratio of d/D 1 is 1 to 2; a housing surrounding at least the outlet straight cylinder section of said acceleration tube and the inlet straight cylinder section of said collection tube, said housing having a side-wall with a side-wall nozzle extending along a nozzle axis; a fine particulate collector, for collecting the fine fraction, connected to said side-wall nozzle; a large volume suction device connected to a downstream side of said fine particulate collector for drawing air at a second flow rate FR 2 through said side-wall nozzle; a coarse particulate collector, for collecting the coarse fraction, connected to the discharge end of said collection tube; and a small volume suction device connected to a downstream side of said coarse particular collector for drawing air at a third flow rate FR3, smaller than said second flow rate FR2, through said inlet of said collection tube.