The sand trap louvre, type GB900, is an external louvre used in dry, dusty or sandy environments. Especially designed to remove the bulk of airborne sand and dust from inlet air whilst maintaining reasonable air flow rate characteristics by means of a special double U-blade design. Sand and dust are evacuated from the base of the louvre by a special sand collection/disersion cill, keeping maintenance to a minimum. The sand trap louvres can be used as natural ventilators or to alleviate the load on the main filtration stages of air conditioning equipment.