The microorifice uniform deposit cascade impactor (MOUDI) is a versatile instrument for collecting sub 3 mu m size-resolved aerosol samples for chemical analysis. The instrument operates at a sampling rate of 30 liters per minute, ensuring that adequate samples of the major atmospheric aerosol species can be collected with sampling times of 1-12 hours, depending on ambient loadings and on analytical sensitivities. Size cuts as small as 0. 05 mu m can be achieved, and particles smaller than this are collected on an afterfilter. The collection substrates consist of 37 mm disks that can be prepared from any material that is compatible with the technique to be used for chemical analysis; in previous work, Telfon filter material and baked aluminum foil have been used as impaction substrates. Furthermore, the pressure drop through the impactor is small relative to that found in other similar instruments. Three prototypes of the microorifice impactor have been developed since the design principles were first reported. Design parameters and performance characteristics for the third prototype MOUDI are summarized.
|Original language||English (US)|
|Number of pages||4|
|State||Published - Dec 1 1986|