Free 20-question practice test covering liquid surge, baffled and smooth bore tanks, rollover risk, and the unique handling demands of tanker operation. Required for the Tanker (N) endorsement.
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A Tanker (N) endorsement is required when operating a vehicle with a liquid or gaseous cargo tank with an individual capacity over 119 gallons AND a total combined capacity of 1,000 gallons or more.
Liquid surge is the forward-and-backward or side-to-side movement of liquid in a partially filled tank during acceleration, braking, or turning. Surge can push a vehicle beyond what the brakes or steering can control, extending stopping distance and increasing rollover risk.
A partially full tank — especially 70-90% full — is the most dangerous because there is enough liquid to create violent surge with room to move. A completely full tank has no room for surge. An empty tank has nothing to surge.
A baffled tanker has internal dividers with holes that reduce the speed and force of liquid surge. A smooth bore tanker has no internal dividers — liquid can move freely end to end. Smooth bore tanks (common in food-grade applications) have the most extreme surge.
Tankers have a high center of gravity, and liquid surge adds additional lateral force in turns. The rollover threshold for tankers is much lower than for dry freight. Many rollovers happen at speeds that would be completely safe in a box trailer.