This approach has become known as ventilation. They are two basic types of industrial ventilation local exhaust and dilution ventilation. Local exhaust systems capture or contain contaminants at their source before they escape into the work environment. Dilution ventilation systems on the other hand allow the contaminants to escape into the work environment. The contaminants concentrations are lowered to safe levels by dilution with fresh air before reaching the employee breathing zone. Where employees are close to the emission source.
Local exhaust is usually superior to the Aleutian if it is feasible. Both type a ventilation require tempered heated or cooled makeup air to replace a redraw stood through the ventilation system. Think about it hair removed must always be replaced. It is best to do this through designed and installed makeup air system. Sometimes the makeup hair is provided by the buildings. Heating and cooling system. The local exhaust system consists of five important components hood, lot , air cleaner , fan and stack the hood is the most important part of the system. No local exhaust system will work properly unless enough for the contaminants are retained or captured by the hood.