This part of ISO 10440 specifies requirements for dry and oil-flooded, helical-lobe rotary compressors (see Figure 1) used for vacuum or pressure or both in petroleum, petrochemical, and gas industry services. It is intended for compressors that are in special-purpose applications. It is not applicable to general-purpose air compressors, liquid-ring compressors, or vane-type compressors. NOTE Standard air compressors are covered in ISO 10440-2.