R.I. Gen. Laws § 21-2.1-3: Frequency of calibration required.

Every farm milk holding tank (when used as a measure) shall be recalibrated at least once every three (3) years. Following the calibration, testing, and sealing as set forth in § 21-2.1-1, the state sealer of weights and measures of the department of labor and training shall issue and deliver to the owner of the milk holding tank a gallonage chart and weight conversion chart applicable to that holding tank.