The Series 230 high volume cascade impactors are designed to fractionate suspended particulates into several size fractions. They are attached to a high volume air sampler and operate at a flow rate of 40 cubic feet per minute. The impactor separates particulates larger than 7.2µm to less than .49µm using a slotted impactor design. The cascade design collects particles on small lightweight substrates that are analyzed for respirable particulate matter.

The impactor has several models available with 1, 4, 5, and 6 impactor stages, allowing for flexibility in the fractionation process. Suspended particulates enter through the first set of parallel slots on the first stage. Larger particles that are too large to travel to the next stage are impacted on the collection substrate, while smaller particles remain in the air stream and travel to the next stage. The slots on each stage are the same width, but as the particulates continue through, the slots become successively smaller, and most of the particulates will eventually become impacted on one of the collection stages. After the last stage, the smallest particles are collected on the backup filter, which is weighed for particle size distribution analysis.