Unit operation
Unit operation means one or more pieces of process equipment used to make a single change to the physical or chemical characteristics of one or more process streams. Unit operations include, but are not limited to, reactors, distillation units, extraction columns, absorbers, decanters, condensers, and filtration equipment.
Source
40 CFR § 63.1423
Scoping language
The following terms used in this subpart shall have the meaning given them in subparts A ( 63.2), F ( 63.101), G ( 63.111), and H ( 63.161) as specified after each term: