Miss. Code § 75-57-115
The board shall require that metering equipment in delivery vehicles used in dispensing of liquefied compressed gas shall be calibrated to an accuracy of a plus or minus tolerance of two percent (2%) at least once a year. This requirement shall not apply to delivery vehicles used in dispensing anhydrous ammonia. All retail stationary dispensing equipment with dispensing capabilities of less than fifty (50) gallons per minute shall be calibrated to an accuracy of a plus or minus tolerance of two percent (2%) every two (2) years. Certificates showing such calibration shall be kept at the dealer's place of business and shall be presented upon demand of the Commissioner of Insurance for inspection by the board. This section shall not apply to anhydrous ammonia dispensing equipment.
Miss. Code § 75-57-115