Cascade impactor

A cascade impactor measures the reach range of a particulate substance as it moves through an opening with the use of aerosol.

An impactor is a device that classifies particles present in a sample of air or gas into known size ranges.

The air jets from these nozzles impact on plane sampling surfaces and each stage collects finer particles than its predecessor.

The samples may be analysed under the microscope or by any method of chemical analysis that may be suitable for obtaining the mass of material of interest on each stage, e.g. atomic absorption or gas chromatography-mass spectrometry (GC/MS).

By using suitable pumps, jet dimensions can be decreased to the point where the velocity is close to that of sound, enabling particles down to about 0.25 μm to be impacted.