40 CFR § 60.71
Definitions
June 9, 2020
As used in this subpart, all terms not defined herein shall have the meaning given them in the Act and in subpart A of this part.
(a) Nitric acid production unit means any facility producing weak nitric acid by either the pressure or atmospheric pressure process.
(b) Weak nitric acid means acid which is 30 to 70 percent in strength.