Apparatus for collection of particulate matter from an ambient gas

Claim 1

Apparatus for collecting microscopic particulate matter from a test atmosphere comprising, a closed evacuable chamber having a body portion and a lid portion, said chamber having interior walls including a side wall, a floor and a ceiling, support means disposed within said chamber for supporting a substrate, a nonporous substrate positioned on said support means in spaced apart relation to said chamber ceiling, said substrate having a substantially planar disk shape and having a periphery less than the lateral periphery of said chamber, said substrate extending along a substantially horizontal plane and having an upper surface and a lower surface, gas inlet means for directing a stream of gas from the exterior of the housing for impingement upon said upper surface of the substrate, said gas inlet means being an inlet tube penetrating said lid portion of said housing, said inlet tube having a hollow center bore directed at substantially the center of said substrate, said inlet tube being spaced apart from said substrate by a distance less than the distance between said substrate and said chamber ceiling, at least a portion of said inlet tube having an interior wall diameter in the range of 0.015 inches and 0.025 inches and said bore having an outwardly flared outlet portion, whereby said inlet tube induces turbulence to a stream of gas progressing therethrough, and vacuum port means disposed below the level of said plane upon which the substrate extends for directing a stream of gas from the interior of the housing to the exterior thereof.