초록 ▼

Disclosed is a virtual impactor for separating particles of a predetermined size range from an aerosol, and for transporting the separated particles from the region they are separated from the aerosol to an analysis/collection region remote therefrom. The device comprises a conduit member having an

Disclosed is a virtual impactor for separating particles of a predetermined size range from an aerosol, and for transporting the separated particles from the region they are separated from the aerosol to an analysis/collection region remote therefrom. The device comprises a conduit member having an inlet end and an outlet end. The conduit member is configured to define a substantially enclosed passageway between the inlet end and the outlet end. At least a portion of the conduit member is gas-permeable. The outlet end of the conduit member is positioned adjacent to the analysis/collection region. The virtual impactor is moved relative to the aerosol to be sampled (or the aerosol is moved relative to the impactor). The virtual impactor utilizes an operating gas that is introduced into the impactor through the gas-permeable portion of the conduit member. The operating gas is then bifurcated into a counterflow fraction that exits the inlet end of the conduit member, and a transporting flow fraction that passes along the conduit member to the analysis/collection region. The counterflow fraction is readily adjustable to control the size of the particles entering the analysis/collection region. Since the operating gas is introduced into the conduit member through the permeable portion of that member, separated particles transported therein are prevented from colliding with the inner surface of the conduit member and are thus not lost or contaminated.

대표청구항 ▼

A device for separating particles from an aerosol where one of the device and the aerosol is in motion relative to the other and for transporting the separated particles, comprising: (a) a conduit member having an inlet end and an outlet end and defining a substantially enclosed passageway between i

A device for separating particles from an aerosol where one of the device and the aerosol is in motion relative to the other and for transporting the separated particles, comprising: (a) a conduit member having an inlet end and an outlet end and defining a substantially enclosed passageway between its inlet and its outlet end, at least a portion of the conduit member that defines the passageway being gas-permeable, the passageway being adapted to receive at least a portion of the aerosol\s particles through the inlet end as a result of the relative motion of the device and the aerosol; and (b) operating flow means associated with the conduit member for directing a gas through the gas-permeable portion of the conduit member and into the passageway, wherein a first fraction of the gas that is directed into the passageway exits the conduit member through the inlet end thereof, and wherein a second fraction of the gas that is directed into the passageway exits the conduit member through the outlet end thereof, a flow rate of the first fraction of the gas being adjustable to prevent passage through the passageway of some of the portion of the aerosol\s particles, wherein aerosol particles received in the inlet end of the conduit member and not prevented from passing through the passageway by the first fraction of the gas are transported by the second fraction of the gas to the outlet end of the conduit member. A method for separating particles from an aerosol and transporting those separated particles through a conduit member that defines an interior passageway having an inlet and an outlet, wherein at least a portion of the conduit member is gas-permeable, the method comprising the steps of: (a) creating relative movement between the conduit member and the aerosol so that at least a portion of the aerosol is directed toward the inlet of the passageway of the conduit member; (b) directing an operating gas through the gas-permeable portion of the conduit member; (c) drawing a fraction of the gas that was directed through the gas-permeable portion of the conduit member out of the outlet of the passageway, whereby the remaining fraction of the gas exits the inlet of the passageway; and (d) controlling the flow of the operating gas so that the fraction of the gas that exits the inlet of the passageway forces a portion of the aerosol particles therefrom and so that the fraction of the gas that is drawn out of the outlet of the passageway transports the remaining particles in the passageway out of the passageway outlet.