Tanker · Baffled, Un-baffled, and Compartmented Tanks

Baffles are fitted to a liquid tank to control surge. Which kind of surge do they do least about, and what does that leave the driver exposed to?

1.Side-to-side surge, which baffles do very little to stop, so a lateral wave can still roll the vehicle during a turnCorrect answer

2.Forward and backward surge, which baffles were never meant to reduce, since that axis is already handled by the tank's own ends

3.Both kinds equally, since all a baffle does is slow the liquid's rotation inside the compartment regardless of direction

4.Neither, because a baffled tank handles exactly like a solid load once the baffles are installed and the vehicle is moving

Explanation

Baffles help control the forward and backward surge, but side-to-side movement can still occur, and a lateral wave in a top-heavy tank is a rollover risk during a turn or a lane change. The reason is geometric: a transverse baffle stands across the path of a fore and aft wave but offers nothing to a wave travelling the width of the tank, so the one axis is damped and the other is not. 49 CFR 383.119(c) makes the differences in handling between baffled or compartmented tank interiors and non-baffled vehicles a required knowledge area for this endorsement, but it names no axis and describes no behaviour, so which surge a baffle catches is manual teaching rather than a codified fact. The wrong options reverse which axis the baffle works on, reduce a baffle to a swirl-breaker, or make a baffled tank equivalent to a solid load, which is the specific overconfidence this part of the manual exists to prevent.

Source: 49 CFR 383.119(c)

Drill Baffled, Un-baffled, and Compartmented Tanks questions

Baffles are fitted to a liquid tank to control surge. Which kind of surge do they do least about, and what does that leave the driver exposed to?

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