Tenn. Code Ann. § 53-3-110: Only approved standard scales, weights, measures and tests to be used

(a) Every person or agent for any person, buying milk or cream on the basis of its weights or chemical or physical constituents, as determined by an approved test, shall use only standard scales and measures approved by the commissioner and only standard weights and tests, bottles and pipettes approved by the commissioner.

(b) It is unlawful for any person to sell the articles listed in subsection (a) to anyone to be used for the purposes stated in subsection (a), unless they have been approved, as required in subsection (a), by the commissioner.