247SimpleTests
CDL · Loading and Unloading

When loading or unloading a tank truck of flammable liquids, what is required?

Reviewed by Jordan Morley, Editorial Lead at 247SimpleTests. Written by the 247SimpleTests Editorial Team from the official source material cited on every question.

Correct answer

Engine must be turned off during loading/unloading unless required to operate the pump, and the truck must be bonded and grounded to dissipate static electricity

  1. A Driver may leave the vehicle unattended
  2. B Engine must be turned off during loading/unloading unless required to operate the pump, and the truck must be bonded and grounded to dissipate static electricity
  3. C Smoking is permitted at the back of the truck
  4. D Engine must be running to power the pump

Why this is the answer

Loading and unloading flammable liquids — gasoline, jet fuel, ethanol, etc. — requires extreme care because vapors form an explosive mixture with air. The engine is turned off unless required to power the truck's loading pump. Bonding wires connect the truck to the loading rack, equalizing static electrical potential so static sparks cannot ignite vapors. Grounding wires connect the truck to earth ground for the same purpose. The driver must remain at the loading point throughout — never leave the truck unattended during a transfer. Smoking, open flames, and even cell phones with potentially spark-causing characteristics are prohibited within the regulated distance (typically 25 feet). A static spark in a vapor cloud has caused many catastrophic refinery and terminal fires.
Source: FMCSA CDL Manual 9.3.5 Loading Flammable Liquids

Practice more questions

This question is from our CDL Practice Tests practice test. Take the full practice test to test your knowledge across all Loading and Unloading and other topics.

Take the Hazardous Materials practice test →

About this topic: Loading and Unloading

Loading and unloading hazmat questions cover segregation of incompatible materials, securing the load, the no-smoking and engine-off rules, and the special handling for explosives, flammables, oxidizers and poisons. This is one of 10 Hazardous Materials questions on loading and unloading, each with a full explanation on a single study page.

New to this exam? Our CDL exam guide explains the format, scoring, and how to prepare.

Related questions

Loading and Unloading

Before loading hazmat, what should you do?

 Loading and Unloading

Which of the following must NEVER be loaded with hazmat cargo?

 Loading and Unloading

Can you smoke or allow smoking within how many feet of a vehicle containing Class 1 explosives, oxidizers, or flammables during loading?

 Loading and Unloading

When transporting cylinders of compressed gas, they should be:

State-specific guides

Need information for your state? Our state guides cover local requirements, fees, and what to expect on exam day.

California Texas Florida New York Pennsylvania Illinois Ohio Georgia

Recommended study materials

Study guide

CDL Study Guide (Trivium)

Complete prep for all CDL written tests: general knowledge, air brakes, combination vehicles, hazmat, and all endorsements. Includes full-length practice tests.

Check Price → Study guide

CDL Practice Tests & Flashcards (Accepted Inc.)

600+ practice questions covering every FMCSA knowledge area, plus 400 flashcards for endorsement prep.

Check Price → Study guide

Master the CDL Truck Driver's License (Arco)

Arco's classic CDL prep with in-depth FMCSA manual coverage, endorsement chapters, and scored practice exams.

Check Price →

As an Amazon Associate, CJ Affiliate, and AWIN publisher we earn from qualifying purchases. Links above are affiliate links. Full disclosure →