US Patent 7276098 Tangential in-line air filter

A tangential air filter configuration is designed for applications where there is a potential for a pollutant to back flush out. The tangential in-line air filter reduces air resistance and prevents back flow, allowing the air to traverse through a forced air system during operation without resistance, and absorbs particulates and prevents back flow of fuel vapors when the forced air is at a standstill. The filter medium has a plurality of pleats or corrugations with a longitudinal axis parallel to the forced airflow direction. A diffusion barrier is formed when the forced air is at a standstill. Vapors are not passed or forced through the filter medium; rather pollutants are aggressively absorbed during diffusion.