The ACS 1000 can be fitted with a wide variety of sample inlets including PM1 , PM2.5 or PM10. Ambient air is drawn through the sample inlet and down through an unrestricted ball valve into the various modules.
Humidity reduction is performed using a permeation dryer which utilises a permeable membrane and a source of dry air. The dryer uses a single nafion tube which allows H2O vapour to transfer from the inside of the membrane to the outside, removing it from the sample air. The large inside diameter of the membrane (40 mm) combined with the grounded mesh, minimises particle losses through the dryer.
Dry sample air passes through the inside of a Gore-Tex™ membrane while the outside of the membrane is filled with Milli-Q water.
As the water temperature is controlled to a higher set point, the amount of water vapour transferred inside increases, allowing the relative humidity of the sample air to be directly controlled.