The ZR/ZT 55-900 oil-free screw compressors represent the flag ships of the Atlas Copco compressor fleet. First introduced in the early 1960’s, these machines have developed a well deserved reputation for reliability, longevity and energy efficiency. Atlas Copco was the first to develop oil-free rotary screw air compressors and throughout the years ‘many have imitated but never duplicated’. Z series can be found in every major industry throughout the world and are relied upon for extremely demanding and critical applications.