Why is hood placement such an important factor in the capture of fugitive emissions?
Hood placement is so important in the capture of fugitive emissions because the volumetric gas flow rate required to pull the pollutant into the ductwork varies with the square of the distance between the hood and the pollutant source (see equation below for a freely suspended hood without a flange). Where: #2 What factors affect the determination of the recommended hood capture velocity for a contaminant? Answer: The following factors should be considered when determining the recommended hood capture velocity for a contaminant: • The surrounding air currents • The level of toxicity of the pollutants • The amount of pollutant • The area of the hood opening #3 Describe three hood designs that improve capture efficiency. Answer: Side baffles or flanges on hoods block the movement of clean air into the hood, which allows the hood capture velocity zones to extend outward slightly. Gas flow rates for hoods with side baffles or flanges can be slightly lower than for hoods without these struc
