Duplex filters for hydraulic and lubrication systems are designed for use in circulating lube oil systems and hydraulic power units, such as found in pulp and paper mills, steel and aluminum mills, refineries and chemical plants, mining, power generation and other industrial locations. The filter elements can easily be changed during operation with a simple turn of our ergonomically designed handle. A special lever in the handle allows switching and pressure compensation with one hand. Thanks to this patented one-hand switch, the system can continue to run without interruption. When filter elements need to be replaced, a standard maintenance indicator signals the production floor. In continuous running filter systems, the elements can be removed and replaced in one filter housing while the other filter housing takes over. In larger filter systems, the elements can be removed from the top. The systems meet the highest demands in terms of ergonomics and economy.