Flow characteristics of a local exhaust system

This paper presents the study of a local exhaust ventilation system with plain (unflanged) and flanged hoods. Centerline velocity and velocity contours in front of exhaust hood openingswere measured and compared to other previously reported results. Centerline velocity correlations are derived for a full range of hood axes. The effect of turbulence intensity and surrounding equipment on the velocity contours is also analyzed. Capture velocity for three different types of contaminant particles (saw dust, wheat flour, and sand) was determined. Flanged hoods provide higher velocity compared to plain hoods in front of the exhaust opening. Surrounding equipmentblocks the energy of the moving flow and tends to reduce the reach of exhaust hoods. Source location has an appreciable effect on the capture velocity for wheat flour and saw dust butlittle effect on the sand particles.