Particle concentrating sampler
AssigneeRegents of the University of Minnesota
InventorsBenjamin Y. H. Liu, Virgil A. Marple
Life of this patent
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Abstract
A particle concentrating sampler utilizes a virtual impactor, which is an inertial classifier, for concentrating airborne particles above a cut size into a smaller volume air. The concentrated particles are counted, or collected on impactor plates or by using other collection techniques, such as filters or electrostatic precipitators. The concentration of the larger particles which are of interest for analysis insures that the number of particles, particularly in clean room environments, is sufficient so that a significant sampler or count can be obtained without sampling large volumes of air.
Claims6
A particle concentrating sampler and collector comprising a housing, said housing being made up of a plurality of sections, including a base, an intermediate section, and a top cap, said top cap having an interior and a top wall;
- a nozzle in said top wall centered along a central axis;
- a receiver tube mounted on the interior of said cap;
- a support for holding said receiver tube, said receiver tube having a central opening aligning with said central axis, and said support defining a space therearound on the interior of said cap for providing a first flow passage;
- means for removing a major flow of air through said nozzle and first flow passage;
- an impactor plate supported with respect to said support in alignment with said receiver tube;
- and
- means for establishing a minor flow through said receiver tube whereby the particles carried through said receiver tube strike the impactor plate.
A particle concentrating collector comprising virtual impactor means including a housing having an inlet nozzle;
- a receiver tube mounted on the interior of the housing and aligning with the inlet nozzle for receiving particle carrying inlet air, and being spaced from the inlet nozzle;
- first outlet passageway means extending laterally of a space defined between the inlet nozzle and the receiver tube;
- means for establishing a first major flow through said first outlet passageway;
- means for establishing a minor flow through said receiver tube and through a second outlet passageway, said minor flow being a small percentage of the major flow;
- and
- means for collecting particles directly from said receiver tube comprising an impactor plate mounted on said housing immediately in line with said receiver tube, and a secondary passage receiving particles which bounce off said impactor plate for carrying said particles which bounce off the impactor plate in said minor flow.
Dependencies are inferred from the claim text.