particulatefiltering

Particulate filtering is the process of removing solid or liquid particles suspended in a gas or liquid by passing the mixture through a porous medium called a filter. The aim is to reduce particle concentrations to protect health, equipment, or processes. Filtration relies on physical mechanisms such as diffusion for very small particles, interception and impaction for larger ones, and often electrostatic attraction to improve capture.

Filter media vary by application. Depth filters trap particles throughout a thick fibrous matrix, while surface filters capture mainly on or near the surface. Common materials include glass or synthetic fibers, cellulose, and membranes. High-efficiency filters, such as HEPA and ULPA, remove a large fraction of particles down to about 0.3 micrometers. In gas streams, activated carbon may adsorb odors or volatile compounds, while liquids use cartridge or depth filters and membranes to remove solids.

Performance is described by removal efficiency for target particle sizes and by pressure drop across the filter, which affects energy use and maintenance intervals. Standards and test methods vary by region, with classifications such as HEPA/ULPA and ISO 29463 or EN 1822 used for air filters.

Applications include HVAC and air purifiers for indoor air quality, automotive cabin filtration, and industrial or pharmaceutical processing. Maintenance involves selecting appropriate media, monitoring efficiency and resistance, and timely replacement to prevent bypass and reduced protection. Challenges include fouling, microbial growth on moist filters, and compatibility with process fluids.