Air compressor means a compressor designed to compress air that has an inlet open to the atmosphere or other source of air, and is made up of a compression element (bare compressor), driver, mechanical equipment to drive the compressor element, and any ancillary equipment.
10 CFR § 431.342
The following definitions are applicable to this subpart, including appendix A. In cases where there is a conflict, the language of the definitions adopted in this section take precedence over any descriptions or definitions found in any other source, including in ISO Standard 1217:2009(E), Displacement compressors - Acceptance tests, as amended through Amendment 1:2016(E), Calculation of isentropic efficiency and relationship with specific energy (incorporated by reference, see 431.343). In cases where definitions reference design intent, DOE will consider all relevant information, including marketing materials, labels and certifications, and equipment design, to determine design intent.