Tank vehicle’ means a commercial motor vehicle that is designed to transport any liquid or gaseous material within a tank or tanks having an individual rate capacity of more than 119 gallons and an aggregate rate capacity of 1,000 gallons or more that is either permanently or temporarily attached to the vehicle or the chassis. ‘Tank vehicle’ does not include a commercial motor vehicle transporting an empty storage container tank that has a rated capacity of 1,000 gallons or more and that is temporarily attached to a flatbed trailer. [1989 c.636 § 7; 2013 c.237 § 49; 2017 c.190 § 10]