Hyderabad Pollution Controls Limited supplies High Ratio Bag Filters Air Pollution Control Equipment. Hyderabad Pollution Controls Limited manufactures industrial ventilation, air pollution control equipments & air handling systems. High Ratio Bag Filters Air Pollution Control Equipment is a solution to industrial problems of dust pollution and product recovery. High Ratio Bag Filters Air Pollution Control Equipment in which non-woven needle felt bags are used for filtration. Reverse pulsejets are employed for cleaning the bags. The air pollution control equipment has the cleaning operation which is controlled by sequential timers. The ratio of air surface area of filter is very high compared to the old type surface filters. This high ratio is achieved by the choice of a new generation of non-woven filter media.