Code of Federal Regulations Title 27. Alcohol, Tobacco Products and Firearms § 27.19.182 Tanks—general requirements

(a) Used for the purpose listed on the application and plant registration;

(b) Equipped with accurate means for measuring their contents. If the means for measurement is not a permanent fixture on the tank, the proprietor must equip the tank with a fixed device for measuring the contents. However, tanks having a capacity of less than 101 gallons are not required to have permanent gauge devices;

(c) Accurately calibrated if used for any of the gauges described in this part. Further, if tanks or their gauging devices are moved in any manner subsequent to original calibration, the tanks shall not be used until recalibrated;

(d) Accessible through walkways, landings, and stairs that permit access to all parts of the tank;

(e) Equipped or situated so that they may be locked or secured;  and

(f) Constructed to prevent access to the spirits or wines through vents, flame arresters or other safety devices.