CFR > Title 27 - Alcohol, Tobacco Products and Firearms > CHAPTER I—ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY > SUBCHAPTER A—LIQUORS (parts 1 to 31) > PART 25—BEER > SUBPART D—Construction and Equipment (§25.31 to §25.36) > 25.35—Tanks.

25.35—Tanks.

Each stationary tank, vat, cask or other container used, or intended for use, as a receptacle for wort, beer or concentrate produced from beer shall:
(a) Be durably marked with a serial number and capacity; and
(b) Be equipped with a suitable measuring device. The brewer may provide meters or other suitable portable devices for measuring contents of tanks or containers in lieu of providing each tank or container with a measuring device.

Code of Federal Regulations

(Sec. 201, Pub. L. 85-859, 72 Stat. 1395, as amended ( 26 U.S.C. 5552 ))