# US 2014/0196549 A1 · Cascade Impactor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0196549 A1 - Document ID: US20140196549A1 - Status: Published application - Kind: A1 - Application number: 14/164,192 - Filed: 2014-01-25 - Published: 2014-07-17 - Earliest claimed: 2007-10-02 - Inventors: Clyde L. Witham - Web page: https://patentgrep.com/patent/US20140196549A1 ## CPC - G01N 1/2208: {with impactors} - B01D 45/08: by impingement against baffle separators - B01D 46/10: Particle separators, e.g. dust precipitators, using filter plates, sheets or pads having plane surfaces - B01D 50/20: Combinations of devices covered by groups B01D45/00 and B01D46/00 - G01N 15/0255: {with mechanical, e.g. inertial, classification, and investigation of sorted collections (with centrifuges G01N15/042)} - G01N 2015/0261: {using impactors} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) ## Abstract The invention relates to low flow rate cascade impactors for sampling aerosols, notably but not limited to pharmaceutical aerosols. The impactor stages serve as both orifice plate and collecting cup, simplifying collection and analysis. The impactor is designed to operate at flow rates approximating the inspiratory flow rates of young children and infants. Also presented is a method of and apparatus for applying a coating material to the collection surface of the stages after an impactor is assembled for use. The method entails generation of a polydisperse aerosol and sampling into the impactor. The coating substance improves the trapping of particles on the stages. The apparatus and method of application limit the amount of coating material applied and confines it to the regions of particle impact opposite the stage orifices. ## Claims ### Claim 1 A cascade impactor comprising: a series of one or more concentrically-arranged collection stages and a terminating filter or filter adapter stage, each collection stage comprising an elongated structure with a cylindrical shape, said elongated structure having a top end and a bottom end, the walls of said elongated structure having an inner surface and an outer surface and further characterized by a single inner diameter, a first outer diameter, and a second outer diameter, the top end being open and the bottom end being closed with a flat surface, said elongated structure further comprising a region wherein the second outer diameter is less than the first outer diameter to form a orifice-containing region, the wall of said elongated structure further comprising at least one orifice positioned in said orifice-containing region and perpendicular to said wall and through which aerosol-containing air flows, the first outer diameter of said elongated structure being sized to fit within and slidably seal within the inner diameter of the next stage in the series. ### Claim 2 (depends on 1) The cascade impactor of claim 1 wherein particles entrained in the sampled air are collected on the inner surface of the wall of the next stage in the series. ### Claim 3 (depends on 1) The cascade impactor of claim 1 wherein said filter stage is further sized to receive the first outer diameter of the last collection stage in said series. ### Claim 4 (depends on 1) The cascade impactor of claim 1 wherein said filter stage is connected externally from the series of stages. ### Claim 5 (depends on 1) The cascade impactor of claim 1 designed to operate at a flow rate between about 1 and about 15 lpm. ### Claim 6 (depends on 1) The cascade impactor of claim 1 designed to operate at a flow rate between about 1 and about 10 lpm. ### Claim 7 (depends on 1) The cascade impactor of claim 1 designed to operate at a flow rate between about 2 and about 8 lpm. ### Claim 8 (depends on 1) The cascade impactor of claim 1 designed to operate at a flow rate between about 4 and about 6 lpm. ### Claim 9 (depends on 1) The cascade impactor of claim 1 designed to separate particles with sizes between about 0.1 and about 15 micrometers aerodynamic diameter. ### Claim 10 (depends on 1) The cascade impactor of claim 1 designed to separate particles with sizes between about 0.3 and about 12 micrometers aerodynamic diameter. ### Claim 11 (depends on 1) The cascade impactor of claim 1 designed to separate particles with sizes between about 0.5 and about 8 micrometers aerodynamic diameter. ### Claim 12 A cascade impactor comprising: a series of one or more concentrically-arranged collection stages and a terminating filter or filter adapter stage, each collection stage comprising an elongated structure with a cylindrical shape, said elongated structure having an open top end and a bottom end containing at least one orifice through which aerosol-containing air flows, the walls of said elongated structure having an inner surface and an outer surface and further characterized by a raised portion inside said bottom end, said raised portion sized to establish an orifice-to-collection surface distance, the outer diameter of said elongated structure being sized to fit within and slidably seal within the inner diameter of the next stage in the series. ### Claim 13 (depends on 12) The cascade impactor of claim 12 wherein particles entrained in the sampled air are collected on the inner surface of the bottom end of the next stage in the series. ### Claim 14 (depends on 12) The cascade impactor of claim 12 wherein said filter stage is further sized to receive the outer diameter of the last collection stage in said series. ### Claim 15 (depends on 12) The cascade impactor of claim 12 wherein said filter stage is connected externally from the series of stages. ### Claim 16 (depends on 12) The cascade impactor of claim 12 designed to operate at a flow rate between about 1 and about 15 lpm. ### Claim 17 (depends on 12) The cascade impactor of claim 12 designed to operate at a flow rate between about 1 and about 10 lpm. ### Claim 18 (depends on 12) The cascade impactor of claim 12 designed to operate at a flow rate between about 2 and about 8 lpm. ### Claim 19 (depends on 12) The cascade impactor of claim 12 designed to operate at a flow rate between about 4 and about 6 lpm. ### Claim 20 (depends on 12) The cascade impactor of claim 12 designed to separate particles with sizes between about 0.1 and about 15 micrometers aerodynamic diameter. ### Claim 21 (depends on 12) The cascade impactor of claim 12 designed to separate particles with sizes between about 0.3 and about 12 micrometers aerodynamic diameter. ### Claim 22 (depends on 12) The cascade impactor of claim 12 designed to separate particles with sizes between about 0.5 and about 8 micrometers aerodynamic diameter. ### Claim 23 (depends on 1) The cascade impactor of claim 1 wherein one or more of the stages contain orifices in the bottom surface of the stage. ### Claim 24 A cascade impactor comprising a series of one or more concentrically-arranged collection stages and a terminating filter or filter adapter stage, each collection stage comprising an elongated structure with a cylindrical shape, said elongated structure having a top end and a bottom end, the walls of said elongated structure having an inner surface and an outer surface and further characterized by a first inner diameter, a second inner diameter, a first outer diameter and a second outer diameter, the top end of each stage being open and the bottom end being closed with a flat surface, said elongated structure further comprising a region wherein the second outer diameter is less than the first outer diameter to form a orifice-containing region, and a region wherein the first inner diameter is greater than the second inner diameter forming a step feature, the wall of said elongated structure further comprising one or more orifices positioned in said orifice-containing region and perpendicular to said wall and through which aerosol-containing air flows, the first outer diameter of said elongated structure being sized to fit within and slidably seal within the first inner diameter of the next stage and rest upon the step feature of said next stage in the series. ### Claim 25 (depends on 24) The impactor of claim 24 wherein more than one orifice is present in said orifice-containing region ### Claim 26 (depends on 25) The impactor of claim 25 wherein said orifices are spaced equidistant around the circumference of the stage wall. ### Claim 27 (depends on 24) The impactor of claim 24 wherein the first and second inner diameters are the same for the first stage. ### Claim 28 (depends on 24) The impactor of claim 24 wherein particles entrained in the sampled air are collected on the inner surface of the wall of the next stage in the series. ### Claim 29 (depends on 24) The impactor of claim 24 wherein particles entrained in the sampled air are recovered from the bottom of the next stage in the series. ### Claim 30 (depends on 24) The impactor of claim 24 wherein a filter stage is further sized to receive the first outer diameter of the last collection stage in said series. ### Claim 31 (depends on 24) The impactor of claim 24 wherein a filter stage is connected externally from the series of collection stages. ### Claim 32 (depends on 24) The cascade impactor of claim 24 designed to operate at a flow rate between about 1 and about 15 lpm. ### Claim 33 (depends on 24) The cascade impactor of claim 24 designed to operate at a flow rate between about 1 and about 10 lpm. ### Claim 34 (depends on 24) The impactor of claim 24 designed to operate at a flow rate between about 2 and about 8 lpm. ### Claim 35 (depends on 24) The impactor of claim 24 designed to operate at a flow rate between about 4 and about 6 lpm. ### Claim 36 (depends on 24) The impactor of claim 24 designed to separate particles with sizes between about 0.1 and about 15 micrometers aerodynamic diameter. ### Claim 37 (depends on 24) The impactor of claim 24 designed to separate particles with sizes between about 0.3 and about 12 micrometers aerodynamic diameter. ### Claim 38 (depends on 24) The impactor of claim 24 designed to separate particles with sizes between about 0.5 and about 8 micrometers aerodynamic diameter. ### Claim 39 (depends on 24) The cascade impactor of claim 24 wherein excess liquid aerosol is collected in the bottoms of the collection stages. ### Claim 40 An apparatus for simultaneously coating collection surfaces of an assembled cascade impactor comprising: a rechargeable pressure container, a valve contained in said pressure container, and a compressed-air nebulizer connected to said valve via a coupling. ### Claim 41 (depends on 40) The apparatus of claim 40 wherein said valve is external from said pressure container. ### Claim 42 A method of simultaneously coating the collection surfaces of an assembled cascade impactor comprising: creating an aerosol comprising droplets of a liquid coating material with an aerosol generator, drawing said aerosol into the impactor with a vacuum source and depositing said droplets of said coating material on the collection surfaces of the impactor stages. ### Claim 43 (depends on 42) The method of claim 42 wherein diameters of the droplets of said aerosol are varied by varying the operating parameters of the aerosol generator. ### Claim 44 (depends on 43) The method of claim 43 wherein said aerosol comprises droplets having diameters spanning the range of cutoff diameters for the impactor stages. ### Claim 45 (depends on 42) The method of claim 42 wherein said aerosol is generated with a compressed air nebulizer. ### Claim 46 (depends on 45) The method of claim 45 wherein the pressure applied to said compressed air nebulizer is varied to alter the size distribution of said aerosol droplets. ### Claim 47 (depends on 42) The method of claim 42 wherein the aerosol generator is selected from the group consisting of rotary spinning discs, hydraulic, pneumatic, electrohydrodynamic, vibrating orifice, and vibrating mesh aerosol generators. ### Claim 48 (depends on 42) The method of claim 42 wherein the collection surfaces are located on concentrically-arranged impactor stages. ### Claim 49 A method of simultaneously coating the collection surfaces of an assembled cascade impactor comprising: placing a liquid coating material into a compressed air nebulizer, connecting said nebulizer to a pressurized container having a release valve connected to the container, said container being pressurized up to about 10 times the operating pressure of said nebulizer, connecting the nebulizer to the inlet of said impactor, sampling air through said impactor, and opening said valve to aerosolize the coating material. ### Claim 50 (depends on 49) The method of claim 49 wherein said pressurized container is pressurized up to about 5 times the operating pressure of the nebulizer. ### Claim 51 (depends on 50) The method of claim 50 wherein said pressurized container is pressurized up to about 2 times the operating pressure of the nebulizer.