1 Scope This standard covers the minimum requirements for dry and flooded helical lobe rotary compressors (see Figure 1) used for vacuum or pressure or both in petroleum, chemical, and gas industry services. It is primarily intended for compressors that are in special purpose applications. It does not cover portable air compressors, liquid ring compressors, and vane-type compressors. Standard air compressors for light duty are covered in International Standard ISO 10 440: 1995 - Rotary Type Positive Displacement Oil-free Compressors for General Refinery Services Part 2 - Packaged Air Compressors. 1.1 ALTERNATIVE DESIGNS The vendor may offer alternative designs. Equivalent metric fasteners, and flanges may be substituted as mutually agreed upon by the purchaser and the vendor. See Appendix E for list of corresponding national and international standards. 1.2 CONFLICTING REQUIREMENTS In case of conflict between this standard and the inquiry, the inquiry shall govern. At the time of order, the order shall govern.