The term silo implies a vertical cylindrical container for the storage of a bulk commodity such as sugar, grain, lime or cement. Where the storage vessels are of rectangular section they are more likely to be called bunkers. The key factor in controlling emissions from a silo is to take into account how the silo is to be filled. It will be most likely be via a pneumatic conveying system but there is the alternative of a conveyor belt / elevator delivery method.  If the silo is filled using a pneumatic conveyor then the a silo mounted filter is all that is needed, rated to cope with the maximum volumetric flow rate that the pneumatic conveyor blower could deliver. A fan is not needed since the delivery blower provides the air mover. FabriPulse L is the ideal collector. If the silo is filled using an elevator and/or a belt conveyor then the silo must be kept under slight suction to provide a constant in flow of air through the filling opening. A silo top mounted filter is required with an “on-board” fan set. Again FabriPulse L is the ideal collector. According to the material being stored in the silo ATEX may or may not be a requirement.