US Patent 7334453 Modular particulate sampler

A gas sampler includes an impact disc for removing larger particles from a gas flow drawn by a pump and a filter for capturing smaller particles, also positioned in the flow path. The sampler is conveniently dissembled and reassembled to remove and replace the impact disc and the filter. Particles removed, especially on the filter, may be observed or analyzed. The impact disc may be coated with an oil or other viscous substance to enhance its ability to retain larger particles. The flow path may be entirely annular after striking the impact disc—that is, around the outside of the impact disc but a portion of the flow path may proceed directly through a central aperture in the impact disc after striking it.