Classification of cooling towers as non refrigerating machinery means duty at a specified ad valorem rate under tariff. Chir/plywood scantlings and timber/plywood assemblies for erection of cooling towers are classifiable as sawn or chipped wood under Heading 44.03; glass fibre reinforced plastic grids used in towers are classifiable as builders' ware of plastics under Heading 39.25; cooling towers, which cool process water by contact with atmospheric air rather than by refrigeration or air conditioning processes, fall under Heading 84.19 as products other than refrigerating or air conditioning machinery and attract the applicable ad valorem duty.