The FF serie pit filters are used to extract and filter the dust produced during the receiving of cereal. They are installed along the biggest side of the receiving pit in order to not limit the use of the pit. The modular construction system, enables the making up filters, according to plant requirements. Each module is indipendent , provided with a ventilator with a silencer fitted on,the the air depression attracts the dusty air which is retained by the filtering elements. At timed intervals, sleeves are back-washed by a compressed air jet wich causes the fall of dusts.