SL-90-11-4 (RP-524 ) -- Development of Loss Coefficient Data for Compound Exhaust Hoods Using Slots for Air Distribution PDF

Reports on the testing in a purpose-designed and built test facility of 40 different configurations of compound exhaust hood that use slots for air distribution. Data on air distribution and hood losses were collected at three flow rates for each hood. Detailed velocity profile data for the exhausted space in front of the hoods were also collected for three of the hood configurations. States the data showed that the hood loss coefficient varied significantly with hood configuration but was insensitive to changes in slot velocity. Straight take-off hoods tended to have lower loss coefficients and better air distribution than 90deg take-off hoods. Projecting baffles at the edges of the hood face were found to raise air velocities in front of the hood. Theoretical hood loss coefficients calculated using standard methods were found to be accurate for some simple exhaust hood configurations but significantly in error for others.

KEYWORDS: Testing, air flow, pressure drop, air distribution, exhaust hoods.