CDL Tank Emergency Systems and Tank Regulations — Questions and Answers
Question 1: A DOT-specification cargo tank must have an external visual inspection and leakage test at least how often?
- Every 6 months
- Every year (Correct answer)
- Every 2 years
- Every 5 years
Correct answer: Every year
Under 49 CFR 180.407, DOT-specification cargo tanks need an external visual inspection and leakage test at least once each year. The longer 5-year interval applies to pressure retests, not to these checks.
DOT-specification cargo tanks are checked on a schedule. The external visual inspection and leakage test is done every year. Other tests, such as the pressure retest, happen on longer cycles, usually every 5 years. A tank that is past due for a required test should not be loaded with regulated product. Before loading, check the test markings on the tank to make sure the inspections are current.
Question 2: A cargo tank is marked with a test date next to the letter "K". Which test does this code stand for?
- Thickness test
- Pressure test
- External visual inspection
- Leakage test (Correct answer)
Correct answer: Leakage test
The "K" test marking identifies the leakage test. The other letter codes identify other inspections, such as V for external visual and P for pressure.
Cargo tanks carry test and inspection markings showing the type of test and the month and year it was done. The letter codes include V for external visual inspection, K for leakage test, I for internal visual inspection, P for pressure test, and T for thickness test. Reading these markings lets a driver or inspector see whether the tank is current on its required inspections.
Question 3: On the test markings of a DOT-specification cargo tank, what does the letter "P" indicate?
- Pressure test (Correct answer)
- Periodic placard check
- Product compatibility check
- Pump inspection
Correct answer: Pressure test
"P" marks the pressure test. The markings record which test was done and when.
Pressure testing checks that the tank shell can hold the pressure it is designed for. Cargo tanks are marked with the test type letter and the date so inspectors can verify compliance quickly. The pressure retest is normally required at least every 5 years for most DOT-specification cargo tanks. The marking is a quick way to confirm this test has been done.
Question 4: You are loading a tank that is only partly full. Which condition makes liquid surge most likely?
- A tank divided into many small compartments
- A tank filled completely with no air space
- A smooth bore tank partly filled with liquid (Correct answer)
- A tank with a low center of gravity
Correct answer: A smooth bore tank partly filled with liquid
A partly filled smooth bore tank has nothing to slow the liquid, so it can surge forward and back. Bulkheads and full tanks limit that movement.
Liquid surge is the movement of liquid inside a partly filled tank. In a smooth bore tank there is nothing to slow the liquid, so braking or accelerating can push it forward or backward, and the surge can shove the truck. Baffles slow front-to-back surge, and bulkheads divide the tank into compartments. A completely full tank has no room for liquid to move. Drivers must brake early and smoothly with a partly filled smooth bore tank.
Question 5: What is the main reason to leave outage (empty space) when filling a tank with a liquid that expands when warmed?
- To make the tank easier to clean
- To reduce the weight on the axles
- To allow room for the liquid to expand without overfilling or leaking (Correct answer)
- To prevent static electricity from forming
Correct answer: To allow room for the liquid to expand without overfilling or leaking
Liquids expand as they warm, so the outage gives the product room to grow. Without it, the tank could overflow or be stressed.
Outage is the empty space left at the top of a tank. Many liquids expand when heated, so a tank filled to the brim can overflow or leak once it warms. How much outage you need depends on the product and its expansion rate. Products that expand more, and loads that will travel through warmer conditions, call for more room. Following the load planning for the product avoids spills and keeps you within legal weight limits.
Question 6: Product begins leaking from a hose connection while you are unloading a cargo tank. What should you do first?
- Activate the emergency shutoff or stop the flow of product (Correct answer)
- Drive the truck away from the leak
- Wait for the delivery to finish
- Cover the spill with a tarp
Correct answer: Activate the emergency shutoff or stop the flow of product
Stopping the flow, using the emergency shutoff if needed, limits the amount released. Driving away or waiting makes the spill worse.
The emergency shutoff system exists so a driver can quickly stop product flow during a leak or equipment failure. During unloading, if a hose or connection leaks, the first priority is to stop the flow. After that, keep ignition sources away, keep people back, and notify the proper authorities and your employer as required. Knowing where the shutoff controls are located before you start unloading helps you respond fast.
Question 7: When can a driver leave a cargo tank unattended during loading or unloading of a regulated product?
- If the hose is secured to the fitting
- If the driver stays in the cab with the doors closed
- If the driver is within about 100 feet of the truck
- Never, a qualified person must stay attending and watch the tank (Correct answer)
Correct answer: Never, a qualified person must stay attending and watch the tank
Federal rules require a qualified person to attend the cargo tank during loading and unloading, staying within a short distance with a clear view of it. The attendant must be able to act fast.
A cargo tank being loaded or unloaded must be attended by a qualified person. For hazardous materials, the attendant must keep the tank in view and stay within a short distance of it (25 feet under the federal rule), and must know the product's hazards and how to stop the flow. This ensures that a leak or overflow is caught and stopped immediately, rather than after a large release.
Question 8: Before opening the dome of a tank that carries a flammable liquid for loading, what should you do about static electricity?
- Run the engine to charge the battery
- Bond the tank to the fill pipe or grounded system before opening (Correct answer)
- Spray the dome with water
- Wear rubber gloves only
Correct answer: Bond the tank to the fill pipe or grounded system before opening
Bonding the tank to the fill system equalizes the electrical charge so no spark jumps across the opening. Do this before opening the dome.
Flowing flammable liquids can build up static electricity, and a spark near flammable vapors can cause a fire or explosion. Bonding connects the tank and the fill equipment so they have the same electrical potential. Make the connection before you open the dome or connect hoses, and keep it in place until you are done. Keeping the engine off during loading of flammable liquids also removes an ignition source.
Question 9: What should you do when driving a partly filled tank vehicle that will need to stop?
- Brake hard at the last moment
- Apply the brakes early and gently, allowing for liquid surge (Correct answer)
- Pump the brakes repeatedly
- Rely on the engine brake only
Correct answer: Apply the brakes early and gently, allowing for liquid surge
Surge can push the truck as the liquid moves, so braking early and gently keeps control. Hard braking makes the surge worse.
When you brake a partly filled tank, the liquid moves forward and then rebounds. This surge can push the truck ahead as you stop or even move it back, which makes stopping harder. Leave extra following distance, watch the road ahead, and slow smoothly well before you reach a stop. Avoid sudden changes in speed to prevent surge from building.
Question 10: Why is a tank vehicle more likely to roll over on a curve than a flatbed carrying the same weight?
- Tank vehicles have wider tires
- The liquid load raises the center of gravity and can shift in the curve (Correct answer)
- The tank steel makes the truck lighter
- Tank vehicles have weaker brakes
Correct answer: The liquid load raises the center of gravity and can shift in the curve
A tank has a high center of gravity, and liquid shifting to the outside of a curve adds to rollover risk. Reducing speed before the curve is the best protection.
Liquid cargo in a tank sits relatively high, giving the vehicle a high center of gravity. In a curve, the liquid can slosh toward the outside, pushing the vehicle further toward tipping. Take curves and ramps well below the posted speed, slow down before entering the curve rather than during it, and avoid sudden steering. Rollovers are one of the most serious risks for tank vehicles.
