What the N endorsement covers
Tank authority applies when liquid or gaseous material is transported in qualifying permanently or temporarily attached tanks. The vehicle class still depends on weight and combination.
Primary test hazards
Liquid surge, expansion space, rollover, braking, curves, smooth-bore tanks, bulkheads, baffles and loading rules.
CLP use
A CLP may carry the N endorsement, but the permit holder may practice only under the current restrictions and with an empty tank that has been purged of hazardous material when required.