There are several factors that determine the best extractor to use, including location, usage, materials, and quantity of smoke/fume produced. In general, however, the rule of thumb is this: Portable extractors are the best choice for jobsite work, maintenance welding, and production benchwork. Mobile extractors and downdraft tables are best suited for continuous production welding processes. Stationary extractors are also best suited for continuous production processes where floorspace limitations prohibit the use of mobile extractors and downdraft tables.