Driven directly by an integrated frequency inverter, these pumps no longer require any drive transmission. The area in which the units work is 100% oil-free. The integrated speed governor optimises the use of energy by matching delivery to actual demand. This creates high efficiency levels and minimises energy consumption. Suction air remains pulsation-free all of the time. Various accessories, such as intake filter, non-return valve, sound absorbers as well as the air delivery and discharge system, are integrated in the completely soundproof cover structure.