Exhaust Air Systems

Exhaust Air Ventilation Systems are widely used to control toxic gases, vapors, dusts, fumes and mists from various industrial operations and processes. A proper design of an exhaust ventilation system is necessary for the effective removal of airborne contaminants that would otherwise pollute the work environment resulting in health hazards, or nuisance, or cause air pollution. A local exhaust ventilation system usually consists of a number of separate exhaust hoods applied to several different operations and connected by a system of branch and main ducts to a central air cleaning device and common exhaust fan and discharge stack to the outside atmosphere.  Each of these components requires separate consideration in the design of the overall system.

Exhaust Air Systems Overview

Exhaust Air Systems Hood

  • Exhaust Air System hoods should be designed to effectively contain, receive or capture air contaminants.
  • Enclosing hoods should as far as possible be used to totally enclose emission sources. If this is not feasible, partial enclosures using baffles or flanges to increase hood efficiency should be considered.
  • Exterior or capture hoods should be placed as close to emission sources as possible.
  • Exhaust hoods should be designed and located such that the contaminants are removed from the breathing zone of persons at or near the hoods.
  • Exhaust hoods should be placed away from the vicinity of any turbulent air movement.
  • Exhaust hoods should be designed, placed and operated to ensure even air flow into the hoods for consistent and reliable emission control.

Exhaust Air Systems Fan

  • An exhaust fan must be selected to produce the rate of airflow required by the exhaust system. The flow must be developed against the total system resistance, including pressure losses through the hoods, branch and main exhaust ducts and accompanying fittings such as elbows, branch-main junctions as well as those incurred through air cleaners and discharge piping.
  • The exhaust fan should be located near the middle of an array of exhaust hoods rather than at the end if possible; high static pressure or suction branch ducts should be located near the fan.
  • The exhaust fan should be located downstream of the air cleaning equipment to protect it against any corrosive action of the gas or vapours or any abrasive action of the dust which is being collected, and as close to the discharge point as possible.
  • The preferred location for an exhaust fan is outdoors, normally on the roof. Fan location should be chosen such that noise would not be a problem.

Exhaust Air Systems are widely used in Industrial Exhaust hoods, Air pollution control system, Kitchen Exhaust ventilation systems, Bathroom Exhaust ventilation system.

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