Home › Practice › Tanker › Question 43
A foam dam in a tanker is used in:
Correct answer: B. Crude oil and certain petroleum tanks for vapor and surge management
Why: Some petroleum cargo tanks use foam dams to manage product expansion and vapor. Drivers should know the equipment in their assigned tank.
Liquid surge can push a vehicle through an intersection or roll it on a curve. The Tanker endorsement specifically addresses how unbaffled and partially full tanks behave differently from rigid loads.
Know the difference between baffled, unbaffled, and compartmented tanks, the safe outage percentage for liquid expansion, and why front-to-back surge is more dangerous than side-to-side surge.
The Tanker portion of the CDL knowledge exam covers more than this single question. Use this site's full Tanker bank to drill every topic, then test yourself with one of our state-specific practice sets to confirm you are ready for the actual DMV exam in your state. Always check your state's CDL handbook for any local addenda before the test day.
If you are still building your overall CDL foundation, start with the General Knowledge bank — every CDL applicant must pass it — and then work outward to the endorsements you plan to add.
