Non-Rotating, MOUDI Cascade Impactor
The MSP Corp. non-rotating MOUDI, Cascade Impactor operates as a conventional aerosol particle sampler and impactor. In the rotating version, the nozzle and impaction plates rotate relative to each other to form a near-uniform particle deposit across each substrate over a 25-mm or 37mm diameter impaction area. Non-Rotation of the substrates directs the particle aerosol stream to one location on the substrate. A Non-Rotating Cascade Impactor is generally used for Mass measurements.
Nozzle rotation spreads out the particle deposit under each nozzle, thereby reducing the deposited particle mass per unit collector area by a factor up to 1000. More particle mass can thus be collected without overloading the substrate, while providing a uniform particle distribution across the substrate, which supports SEM or TEM particle analysis.
A large number (up to 2000) of very small nozzles (down to 50 µm in nozzle diameter) are used to reduce the impaction velocity and particle bounce. The pressure drop is also lower, thus minimizing evaporative loss of semi-volatile particles during sampling.