Tenn. Code Ann. § 47-26-904: Primary standards

(a) Weights and measures that are traceable to the United States prototype standards supplied by the federal government, or approved as being satisfactory by the National Institute of Standards and Technology (NIST), shall be the state primary standards of weights and measures, and shall be maintained in such calibration as prescribed by the NIST.

(b) The primary standards shall be kept in a place designated by the commissioner and approved by NIST and shall not be removed from such place except for repairs or calibration.

(c) The primary standards shall be used only in verifying the secondary standards and for scientific purposes.