11 Waste-Gas Burners; Air and Gas Filtering Installations for Buildings, Factories, Industrial Plants and Metallurgical Plants-Namely, Electrostatic and Bag Filters and Woven Filter Cloths of Cotton and/or Synthetic Fibers for Use in Such Filters; Gas Cooling Towers and Scrubbers; Fluidized Bed Furnaces; Evaporation Coolers; and Waste Water Treatment Basins