Cargo Surge Flashcards

A tank vehicle is carrying a partially filled load. What is "liquid surge"?

Answer: Movement of the liquid back and forth or side to side inside the tank

Liquid surge is the movement of liquid in a partly filled tank, forward and backward or side to side. It happens when the vehicle accelerates, brakes, or turns.

Which tank design allows the most liquid surge?

Answer: A smooth-bore tank with no baffles

A smooth-bore tank has nothing inside to slow the liquid, so it allows the most severe surge. Baffles and bulkheads restrict movement.

A baffled tank is partly full. Which statement about surge in it is correct?

Answer: Baffles help control front-to-back surge, but side-to-side surge can still occur

Baffles have holes in them and mainly slow forward-and-back surge. Side-to-side surge can still happen, and it can contribute to rollovers.

What is the main reason a compartmented (bulkheaded) tank reduces surge?

Answer: Each compartment is a separate tank, so the liquid cannot surge along the whole length

Bulkheads divide the tank completely, so each compartment acts as a separate tank. Liquid can only surge within its own compartment.

A driver brakes hard on a slippery road with a partly filled smooth-bore tank. What can happen as the vehicle slows?

Answer: The liquid surges forward and can push the vehicle ahead, increasing stopping distance

When you brake, the liquid moves forward and its momentum can push the vehicle ahead. On a slippery surface this can lengthen the stop.

Which action best lowers the risk of surge-related rollover when you approach a curve in a partly filled tank?

Answer: Slow down before the curve, then steer smoothly through it

Reduce speed before the curve and steer smoothly. Hard steering or braking in a curve starts a side-to-side surge that can tip the vehicle.

Which load condition produces the least liquid surge?

Answer: A tank filled completely, within legal weight limits and with outage allowed for expansion

Surge needs empty space in which the liquid can move. A tank filled as full as is safe leaves little room, so it has little surge. Some outage is still left for expansion.

You haul a very dense liquid, such as some acids. Why are such loads often carried in a tank that is only partly full?

Answer: A full tank of a dense liquid could exceed legal weight limits

A dense liquid weighs more per gallon, so a full tank can be overweight. Partial loads are common, which means surge must be managed even though the tank is not full.

Compared with a light liquid, a dense liquid in the same partly filled tank, moving at the same speed, will generally:

Answer: Carry more momentum, so its surge pushes harder on the vehicle

Momentum depends on mass. The same volume of a denser liquid has more mass and delivers a stronger push when it surges.

A tank truck is partly full, and the driver starts off from a stop by accelerating briskly. What is the most likely effect of the surge?

Answer: The liquid moves toward the rear, and the surge can rock the vehicle back and forth

On acceleration the liquid shifts toward the rear, then rebounds forward. The back-and-forth movement can make the vehicle surge and hard to control.