Ventilation is the process by which ‘clean’ air (normally outdoor air) is intentionally provided to a space and stale air is removed. This may be accomplished by either natural or mechanical means. Industrial ventilation is a method of controlling worker exposure to airborne toxic chemicals or flammable vapors by exhausting contaminated air away from the work area and replacing it with clean air. Ventilation is needed to provide oxygen for metabolism and to dilute metabolic pollutants (carbon dioxide and odour). It is also used to assist in maintaining good indoor air quality by diluting and removing other pollutants emitted within a space but should not be used as a substitute for proper source control of pollutants. Ventilation is additionally used for cooling and (particularly in dwellings) to provide oxygen to combustion appliances. Good ventilation is a major contributor to the health and comfort of building occupants. Auto Viscous filter is a self-cleaning viscous air filter using a rotating curtain of metal screen as the filtering media. Behind the filter media roll is an endless roll of oil drop eliminator. When the filter media is loaded and the pressure drop increases, a totally enclosed thermally protected geared motor moves the filter media and oil drop eliminator which pass through a viscous oil bath located at the bottom of the filter. The viscous oil cleans the filter media and the oil drop eliminator ensures that the oil is not carried into the air stream. The sludge collected in the oil bath needs to be cleaned periodically.