This Code provides test procedures to determine the thermodynamic performance of an axial or centrifugal compressor or exhauster doing work on a gas of known or measurable properties under specified conditions. This Code is written to provide explicit test procedures which will yield the highest level of accuracy consistent with the best engineering knowledge and practice currently available. Nonetheless, no single universal value of the uncertainty is, or should be, expected to apply to every test. The uncertainty associated with any individual PTC 10 test will depend upon practical choices made in terms of instrumentation and methodology. Rules are provided to estimate the uncertainty for individual tests. The scope of this Code includes instructions on test arrangement and instrumentation, test procedure, and methods for evaluation and reporting of final results. Rules are provided for establishing the following quantities, corrected as necessary to represent expected performance under specified operating conditions with the specified gas: (a) quantity of gas delivered, (b) pressure rise produced, (c) head, (d) shaft power required, (e) efficiency, (f) surge point, (g) choke point. Other than providing methods for calculating mechanical power losses, this Code does not cover rotor dynamics or other mechanical performance parameters. This Code is designed to allow the testing of single or multiple casing axial or centrifugal compressors or combinations thereof, with one or more stages of compression per casing. Procedures are also included for externally piped intercoolers and for compressors with interstage side load inlets or outlets. Internally cooled compressors are included provided that test conditions are held nearly identical to specified conditions.