This standard covers the minimum requirements for centrifugal compressors used in refinery service that handle air or gas. This standard does not apply to fans or blowers that develop less than 5 pounds per square inch (0.34 bar) pressure rise above atmospheric pressure; these are covered in API Standard 673. This standard also does not apply to packaged@ integrally geared centrifugal air compressors@ which are covered in API Standard 672. Note: A bullet (?) at the beginning of a paragraph indicates that either a decision is required or further information is to be provided by the purchaser. This information should be indicated on the data sheets (see Appendix A); otherwise it should be stated in the quotation request or in the order.