Compressed air from the lab runs through a regulator, (a), then passes through the inlet HEPA filter, (b), and splits into a control valve for the nebulizer and compressed air line. The nebulizer line (d) then goes through its flowmeter, (g), and into the nebulizer, (e), where a solution with 20 - 100 nm gold particles in water is aerosolized and flows into the mixing chamber (acrylic box). The air line (c), enters the mixing chamber directly and is used to control the flow through the filter tube. A thermometer and hygrometer, (f), measures the temperature and humidity in the mixing chamber. The gas passes through a final flowmeter, (h), to control the velocity accross the filter material before entering the larger fitler tube. The filter material is cut into a 2.5 inch circle and held between removeable aluminum plates at (i). A differential pressure gauge, (j), measures the pressure drop from 2in before the filter material and 2in after. The aersoloized air travels 24 inches from the start fo the 2in tube before it hits the filter material to allow for a stabalized laminar flow. Once passing through the material, the nanoparticles are collected in an impinger, (k), and the exhaust is fed through a final HEPA filter (l).
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the entire appartus is kept in a fume hood to protect against inhalation of any stray nanoparticles - for the most aprt we are testing with gold particles which are large enough to not be of huge safety concern, but a lot of safety risks around nanoparticles is still unknown.
