Simple scrubbers have been used in plating and foundry installations for decades. The simplest effluents can be scrubbed and form an airstream with ordinary water sprays. The original scrubbers simply added this scrubber water to the plating or foundry process. Higher capture technology demanded packed towers, staged trays, variable throat venturis and pad-type elements which require higher energy fans and acoustic devices. The fans and duct system must be protected from water and chemical corrosion. Eurovent makes fans in several alloys with special coatings and FRP construction available.