Kaeser Compressors has expanded its line of Sigma Frequency Control (SFC) compressors. BSD and CSD Sigma rotary screw compressors are now available with Kaeser's variable speed drive - specifically designed to achieve maximum efficiency over a wide flow range. Standard SFC compressor packages are available from 40 to 300 hp and flows from 34 to 1568 cfm providing pressures from 80-217 psig.