CDL tank vehicles practice test
The Tank Vehicles (N) test is for you if you haul liquid or gas in a tank. It follows federal rules, so these 130 questions apply in every state.
Tank Vehicles practice test
Answer at your own pace. After each question you see the correct answer and why, and at the end a review of what you missed.
The questions could not be loaded. Check your connection and try again.
Tank Vehicles questions with answers
-
Under federal rules, a tank vehicle carries liquid or gas in a tank whose individual rated capacity is more than how many gallons?
Show answer
Answer B: More than 119 gallons
The federal definition of a tank vehicle starts with a single tank rated at more than 119 gallons, so containers at or below that size do not trigger the rule by themselves.
Source: ecfr.gov
-
For a vehicle to meet the federal tank vehicle definition, what must the aggregate rated capacity of its tanks be?
Show answer
Answer C: 1,000 gallons or more
The definition combines two thresholds: an individual tank rated above 119 gallons and a total rated capacity of 1,000 gallons or more.
Source: ecfr.gov
-
Which letter code on a CDL identifies the tank vehicle endorsement?
Show answer
Answer B: N
Federal rules assign the code N to the tank vehicle endorsement, while H covers hazardous materials and T covers doubles and triples.
Source: ecfr.gov
-
A driver holds an endorsement coded X. What does that single code cover?
Show answer
Answer A: Tank vehicle and hazardous materials together
The X code is the combined form of the tank vehicle and hazardous materials endorsements, used when a driver holds both.
Source: ecfr.gov
-
What must an applicant pass to add the tank vehicle endorsement to a CDL?
Show answer
Answer D: A knowledge test only
Federal rules require only a written knowledge test for the tank vehicle endorsement; a road skills test is required for the passenger and school bus endorsements instead.
Source: ecfr.gov
-
A commercial learner permit holder who has the tank vehicle endorsement may operate which vehicle?
Show answer
Answer B: An empty tank vehicle only
While learning, a permit holder with the tank endorsement is limited to an empty tank vehicle, because surge and rollover risk rise sharply once product is on board.
Source: ecfr.gov
-
Besides being empty, what other condition applies to the tank a learner permit holder with the tank endorsement may drive?
Show answer
Answer C: It must have been purged of residue if it previously held hazardous materials
An empty tank that still holds hazardous residue is treated as loaded for this purpose, so it must be purged before a permit holder may drive it.
Source: ecfr.gov
-
A flatbed trailer carries an empty storage container tank rated at 1,000 gallons or more that was never designed for transportation and is only temporarily secured for the trip. How is this treated federally?
Show answer
Answer A: It is not considered a tank vehicle under the federal definition
The definition carves out an empty storage container tank that is not built for transportation and is riding temporarily on a flatbed, since it is freight rather than a tank vehicle.
Source: ecfr.gov
-
When can a vehicle small enough to fall in the smallest CDL group still require a tank vehicle endorsement?
Show answer
Answer D: When it carries hazardous materials in a tank that meets the federal capacity thresholds
A light vehicle that hauls hazardous materials in a tank meeting the capacity thresholds needs the tank endorsement even though the vehicle itself is not heavy.
Source: oregon.gov
-
A qualifying tank is bolted to the chassis only for this job and will be removed next week. Does it count toward the tank vehicle definition?
Show answer
Answer C: Yes, tanks attached permanently or temporarily both count
The definition applies to tanks attached either permanently or temporarily, so a short term mounting does not exempt the vehicle.
Source: ecfr.gov
-
What does it mean to say that a tank vehicle has a high center of gravity?
Show answer
Answer B: Much of the weight of the load is carried high above the road
In a tank the product fills a tall round shell, so a large share of the weight sits well above the road and makes the vehicle top heavy.
-
What have tests shown about tank vehicles and the speeds posted for curves?
Show answer
Answer A: A tank vehicle can roll over at the speed posted for the curve
Because a liquid load is top heavy, tank vehicles have rolled over at the very speed posted for a curve, so the posted figure is not a safe target.
Source: oregon.gov
-
What speed should a tank vehicle use when entering a curve that has a posted advisory speed?
Show answer
Answer D: Well below the posted speed
A tank vehicle needs a margin under the advisory speed because its high center of gravity and moving load leave far less reserve against rollover.
-
What causes liquid surge in a tank vehicle?
Show answer
Answer C: Movement of the liquid inside a partially filled tank
Surge is the wave action of product that has room to move, which is why a partly filled tank handles worse than a full or an empty one.
Source: oregon.gov
-
When the wave of liquid inside a tank reaches the end of the shell, what happens?
Show answer
Answer A: It tends to push the vehicle in the direction the wave is moving
The wave transfers its energy to the tank head, so the vehicle is shoved along the same line the liquid is traveling.
-
You stop a partly loaded tank at a red light on a slippery road. What can liquid surge do?
Show answer
Answer B: Push the stopped vehicle forward into the intersection
With little grip under the tires, the returning wave can be strong enough to shove a vehicle that has already stopped out into the crossing traffic.
Source: oregon.gov
-
What is a baffle inside a liquid tank?
Show answer
Answer D: A divider with holes that lets liquid pass through slowly
Baffles are perforated dividers, so product can still move from one part of the tank to another but only at a restrained rate.
Source: oregon.gov
-
Which movement of the liquid do baffles help control?
Show answer
Answer A: Forward and backward surge
Baffles sit across the tank, so they slow the wave that runs along its length when you accelerate or brake.
-
Why do baffles fail to protect against side to side liquid movement?
Show answer
Answer C: Tanks are not normally fitted with side to side baffles
Baffles are placed across the length of the tank, and there is normally nothing dividing it from side to side, so lateral waves are free to build.
-
What is the main danger created by side to side liquid surge?
Show answer
Answer D: A rollover
A lateral wave shifts weight toward one side of a vehicle that is already top heavy, which is exactly how tank rollovers begin.
-
What is a smooth bore tank?
Show answer
Answer B: A tank with nothing inside to slow the liquid down
A smooth bore, or unbaffled, tank has a clear interior, so the product can run the whole length of the shell without resistance.
-
How does surge behave in a smooth bore tank compared with a baffled one?
Show answer
Answer A: Forward and back surge is much stronger
With no internal dividers the wave builds without restraint, so a smooth bore tank produces the most violent front to rear surge.
Source: oregon.gov
-
Why are tanks that haul food products such as milk usually built without baffles?
Show answer
Answer C: Sanitation rules call for an interior that can be cleaned thoroughly
Internal dividers trap residue and make washing difficult, so sanitation requirements push food tanks toward a clear smooth bore interior.
Source: oregon.gov
-
What does a bulkhead do inside a tank vehicle?
Show answer
Answer D: It divides the tank into separate compartments
A bulkhead is a solid divider, so each compartment behaves as its own tank and can hold a different quantity or product.
-
When you load or unload a tank that has several compartments, what must you watch?
Show answer
Answer B: That the weight stays balanced and is not piled onto the front or the rear
Compartments can be filled in any order, so it is easy to overload one end of the vehicle unless you plan the sequence and keep the axle loads even.
-
What is outage in tank vehicle loading?
Show answer
Answer A: The empty space left in the tank so the liquid can expand
Outage is the deliberate void above the product that gives the liquid somewhere to go as it warms up.
Source: oregon.gov
-
Why must you leave outage when loading a liquid?
Show answer
Answer C: Because liquids expand as they get warmer
Product loaded cool can gain volume during the trip, and with no space to expand it would press on the shell and force its way out through fittings.
-
Why is the amount of outage not the same for every load?
Show answer
Answer D: Because different liquids expand by different amounts
Expansion depends on the product, so the driver has to know the outage required for the specific liquid being hauled.
-
Which set of factors decides how much liquid you can put in a tank?
Show answer
Answer B: How much the liquid will expand, the weight of the liquid and the legal weight limits
The load is limited by expansion during transit, by the density of the product and by the weight the vehicle may legally carry.
Source: oregon.gov
-
You are loading a very dense liquid. What is likely to happen?
Show answer
Answer C: You will reach the legal weight limit while the tank is only partly filled
A heavy product reaches the legal weight before it fills the shell, which is why dense loads often ride in a partly filled tank with strong surge.
Source: oregon.gov
-
Under federal rules for bulk packagings, what is the minimum outage for a liquid hazardous material that is not poisonous by inhalation?
Show answer
Answer A: At least 1 percent
Bulk liquids must be loaded with at least one percent outage at the stated reference temperature, and a larger margin applies to materials poisonous by inhalation.
Source: ecfr.gov
-
During a pre trip inspection you find a slow drip of product under a loaded tank. What must you do?
Show answer
Answer B: Keep the vehicle out of service until the leak is repaired
Hauling liquid in a leaking tank is prohibited, so the vehicle stays parked until the leak is fixed no matter how small it looks.
Source: dds.georgia.gov
-
What can happen to a driver who hauls liquid in a leaking tank?
Show answer
Answer C: The driver can be cited, put out of service and held responsible for the cleanup
Moving a leaking tank exposes the driver to enforcement action and to liability for the spill, which is why the leak check is the heart of a tank inspection.
Source: dds.georgia.gov
-
What must you confirm about the manhole covers during a tank inspection?
Show answer
Answer D: That the gaskets are in place and the covers are closed and secured
A missing gasket or an unlatched cover lets product escape through the top of the tank as soon as the load starts to surge.
-
Why must tank vents be checked and kept clear?
Show answer
Answer A: So pressure can equalize and the shell is not damaged or the flow blocked
The vent lets the tank breathe, and a blocked vent can build pressure or vacuum inside the shell and interfere with loading and unloading.
-
When should you check that the intake, discharge and cut-off valves are in the correct position?
Show answer
Answer B: Before loading, before unloading and before you move the vehicle
Valve position is checked at every stage of handling the product, because a valve left open turns a normal trip into a spill.
Source: dds.georgia.gov
-
Where are leaks most likely to appear in the piping of a tank vehicle?
Show answer
Answer C: At the connections and joints between pipes and hoses
Joints and couplings carry the seals and take the vibration, so they are the first places to check for weeping product.
-
Which items count as special tank equipment that must be inspected when the vehicle is fitted with them?
Show answer
Answer A: Vapor recovery kits, grounding and bonding cables and emergency shut-off systems
Tank vehicles carry equipment other trucks do not, and each of those systems has to be present and working before the trip starts.
Source: dds.georgia.gov
-
Why must you never move a tank vehicle with an open discharge valve or an open manhole cover?
Show answer
Answer D: Product can escape onto the road and the load can be lost
An open opening lets surging product spill out while the vehicle is in motion, contaminating the road and creating a hazard for everyone behind you.
-
How should you start, slow and stop a tank vehicle?
Show answer
Answer A: Smoothly, with gentle steering inputs
Every abrupt input sets the liquid moving, so smooth acceleration, smooth braking and gentle steering are the basic defense against surge and rollover.
-
How does surge change the way you plan a stop?
Show answer
Answer B: You should begin braking well ahead of the stop and keep extra following distance
Surge adds distance and unpredictability to a stop, so the answer is more space and an earlier, gentler application of the brakes.
-
Which mistake makes surge worse while you are coming to a stop?
Show answer
Answer C: Releasing the brakes too soon
Letting the brakes off before the vehicle has settled frees the wave to shove the vehicle forward just as you thought you had stopped.
-
Which braking method is recommended when a tank vehicle must make a quick stop to avoid a crash?
Show answer
Answer D: Controlled braking or stab braking
Controlled braking and stab braking both keep the wheels from staying locked, which preserves steering and reduces the risk of a skid or jackknife.
-
What is the correct sequence for stab braking?
Show answer
Answer A: Apply the brakes fully, release when the wheels lock, then apply fully again once they roll
Stab braking alternates full application with a release timed to the wheels locking, so the tires regain rolling traction between applications.
-
Why should you avoid turning the steering wheel sharply while braking hard in a tank vehicle?
Show answer
Answer B: The vehicle can skid, jackknife or roll over
Hard braking and a sharp steering input ask the tires for more grip than they have while the liquid is already throwing weight around.
-
What is the recommended way to handle a curve in a tank vehicle?
Show answer
Answer C: Slow down before the curve and then accelerate slightly through it
Braking before the curve settles the load, and a light pull through the bend keeps the combination stretched and stable.
-
How can an empty tank vehicle behave compared with a loaded one when you brake?
Show answer
Answer D: It may take longer to stop than a full one
With little weight pressing the tires down, an empty tank has less traction and its brakes can lock early, so the stop can be longer than when loaded.
Source: oregon.gov
-
What effect can a wet road have on the stopping distance of a tank vehicle?
Show answer
Answer A: It can double the stopping distance
Wet pavement can double the distance needed to stop, which is why speed has to come down and following distance has to grow when it rains.
Source: oregon.gov
-
What should you do with a speed retarder when the road is wet, icy or covered with snow?
Show answer
Answer C: Turn it off
A retarder acts on the drive wheels, and where traction is poor that braking force can make them skid, so it is switched off on slippery roads.
Source: oregon.gov
-
Two trailers weigh the same. One is a tank of liquid and the other is a van of boxed freight. Why does the tank roll over more easily in a curve?
Show answer
Answer C: Its weight rides high in the shell and the liquid can shift sideways
A liquid load fills a tall round shell and can move, so the tank carries its weight higher and lets that weight throw itself toward the outside of the turn.
Source: oregon.gov
-
The trailer of your loaded tank begins to lean as you take a ramp faster than you intended. What is the best response?
Show answer
Answer A: Ease off the accelerator smoothly and avoid any sudden steering or braking
Once a tank starts to lean, an abrupt input is what finishes the rollover, so the cure is a gentle reduction in speed with the steering held steady.
-
Why are highway entrance and exit ramps especially dangerous for tank vehicles?
Show answer
Answer D: Their posted speeds can still be too fast for a top heavy tank
Ramp advisory speeds are set with ordinary vehicles in mind, and a loaded tank has to run well below them to keep a margin against rollover.
Source: oregon.gov
-
Where should your slowing be finished before you take an off-ramp in a loaded tank vehicle?
Show answer
Answer B: On the straight roadway, before you enter the ramp itself
Braking while the tank is already turning asks the tires to brake and corner at once, so the speed has to come off before the curve begins.
-
You will haul potable water in a tank rated well above the federal capacity thresholds. Is the tank vehicle endorsement required?
Show answer
Answer C: Yes, the endorsement follows the tank and its capacity, not the product
The definition of a tank vehicle turns on the rated capacity of the tank, so even a harmless liquid such as water triggers the endorsement.
Source: ecfr.gov
-
You hold the tank vehicle endorsement and are offered a load of flammable liquid that requires placards. What else do you need?
Show answer
Answer A: The hazardous materials endorsement as well as the tank endorsement
The tank endorsement covers the vehicle, not the product, so a placarded load also requires the hazardous materials endorsement.
Source: ecfr.gov
-
To which CDL classes can the tank vehicle endorsement be added?
Show answer
Answer C: To Class A, Class B or Class C, depending on the vehicle driven
Qualifying tanks are mounted on vehicles of every size, so the endorsement is available on all three CDL classes.
-
Under the federal outage rules for bulk packagings, what reference temperature applies to a noninsulated tank?
Show answer
Answer C: 115 degrees Fahrenheit
Outage in a bulk packaging is measured at 46 degrees Celsius, which is 115 degrees Fahrenheit, for a noninsulated tank, so the product still has room to expand on the hottest days.
Source: ecfr.gov
-
The specification plate of a cargo tank shows a maximum weight of lading. What does that figure mean when you load?
Show answer
Answer B: You may not load more than that weight even if the tank still has room
The marked figure is a limit on the tank itself, so a load can be illegal even when there is still space inside the shell.
Source: ecfr.gov
-
Where do you look for the date of the most recent periodic inspection or test of a cargo tank?
Show answer
Answer A: Marked on the tank itself, near the specification plate
Cargo tanks display the month and year of their required tests as markings on the vehicle, so a driver or an inspector can check them on the spot.
Source: ecfr.gov
-
A cargo tank marking shows a month, a year and one or more letters. What do the letters tell you?
Show answer
Answer D: The type of inspection or test that was performed
Each letter stands for a kind of test, such as a visual inspection, a pressure test or a leakage test, so the marking records both the date and the work done.
Source: ecfr.gov
-
How often must a specification cargo tank normally receive an external visual inspection and a leakage test?
Show answer
Answer B: At least once a year
The external visual inspection and the leakage test both fall on a yearly cycle, while other checks such as the pressure test run on longer intervals.
Source: ecfr.gov
-
The periodic retest of the cargo tank you are assigned expired last month. What does that mean?
Show answer
Answer C: It may not be filled and offered for transportation until the test is done
A cargo tank that is out of date on a required test cannot be filled or offered for transportation, so it stays out of service until the work is complete.
Source: ecfr.gov
-
What is the purpose of the emergency shut-off system fitted to a cargo tank used for deliveries?
Show answer
Answer B: It stops the flow of product quickly if something goes wrong while unloading
The system lets the flow be shut down from a point away from the delivery hose, which is exactly what a spill or a fire during unloading demands.
-
A cargo tank of hazardous material is being unloaded at a customer. Where must the qualified attendant be?
Show answer
Answer A: Within 25 feet of the tank with an unobstructed view of it and the hose
Attendance means staying close enough to see the tank and the delivery hose and to act at once, which the rules put at 25 feet.
Source: ecfr.gov
-
What should be done with the engine while a flammable liquid is loaded into or unloaded from a cargo tank?
Show answer
Answer D: Shut off, unless it has to run the pump that moves the product
A running engine is an ignition source standing next to flammable vapor, so it stays off except when it is needed to drive the transfer pump.
Source: ecfr.gov
-
Why are bonding and grounding cables connected before a flammable liquid is loaded into a cargo tank?
Show answer
Answer A: To drain off static electricity so a spark cannot ignite the vapor
Product moving through a hose builds a static charge, and bonding and grounding give that charge a safe path away from the vapor space.
-
What should you do with the vehicle itself before you begin loading or unloading a tank?
Show answer
Answer B: Set the parking brake and chock the wheels so the vehicle cannot move
A tank that rolls while a hose is connected tears the fitting out, so the vehicle is secured against movement before any product flows.
-
What must you confirm about the pressure relief valve during a tank vehicle inspection?
Show answer
Answer C: That it is in place, undamaged and free of anything blocking it
A relief valve that is blocked or damaged cannot vent the shell when pressure rises, which is the one moment it is needed.
-
What should you look for when you inspect the delivery hoses carried on a tank vehicle?
Show answer
Answer A: Cracks, bulges, worn spots and couplings that are secure
A hose that fails under pressure empties product onto the ground in seconds, so its condition and its couplings are checked before every trip.
-
Which finding on the tank shell should keep the vehicle out of service?
Show answer
Answer D: Cracked welds, deep dents or corroded areas in the shell
Damage to the shell or to its welds weakens the boundary that holds the product in, so the tank can no longer be trusted with a load.
-
You deliver part of the product from one compartment of a bulkhead tank and keep the rest for the next stop. What has changed?
Show answer
Answer B: The compartment now has empty space, so the product in it can surge
A compartment that was full and quiet becomes a partly filled tank as soon as product is drawn off, and it will surge for the rest of the trip.
-
You load the rear compartments of a compartmented tank and leave the front ones empty. The gross weight is legal. What is the risk?
Show answer
Answer D: The rear axles can be overloaded even though the total weight is legal
Gross weight and axle weight are separate limits, so piling the load over one group of axles can break the axle limit while the total still looks fine.
-
What does a bulkhead let the operator of a tank vehicle do?
Show answer
Answer C: Carry more than one product at a time in the same tank
Because the dividers are solid, each compartment works as a tank of its own and can hold a different product from the one beside it.
-
Before you start unloading a compartmented tank, what must you be sure of?
Show answer
Answer D: That you know which compartment feeds each outlet
Delivering from the wrong outlet puts the wrong product into the customer tank, so the pairing of compartment and outlet is settled before any valve is opened.
-
Which action is most likely to build up side to side surge in a partly loaded tank?
Show answer
Answer A: Steering back and forth, such as in a quick lane change
A lateral wave is fed by side to side steering, and because nothing inside the shell divides the tank that way the wave is free to grow.
Source: oregon.gov
-
Why is a partly filled smooth bore tank hard to handle in stop and go traffic?
Show answer
Answer B: Every stop and start sends a strong wave along the length of the tank
With nothing inside to restrain it, the product runs to one end each time you brake and back again each time you pull away, shoving the vehicle with it.
Source: oregon.gov
-
Is an empty tank vehicle safe from rolling over?
Show answer
Answer D: No, the tank is still tall and light, and it can roll in a fast curve
Removing the product lowers the weight but not the height of the shell, and the lighter vehicle also has less traction to work with.
-
What should you do before you start down a long steep grade with a loaded tank?
Show answer
Answer A: Slow to a safe speed and select a low gear before the descent begins
Speed and gear have to be right at the top, because a top heavy tank that is already running away will not be recovered with the brakes.
-
The right wheels of your loaded tank drop off the edge of the pavement. What should you do?
Show answer
Answer D: Hold a straight course, slow down, then steer back sharply and countersteer
You stay on the shoulder and let the speed drop first, then take the pavement edge with one sharp steer and an immediate countersteer, because easing back gradually lets the edge grab a tire.
-
Your trailer carries eight mounted tanks, each rated at 150 gallons, for a total rated capacity of 1,200 gallons. Does this meet the federal tank vehicle definition?
Show answer
Answer A: Yes, each tank is rated above 119 gallons and the total is at least 1,000 gallons
Both thresholds are met: every tank is rated above 119 gallons and the tanks together reach 1,000 gallons, so the vehicle is a tank vehicle.
Source: ecfr.gov
-
You carry twelve mounted containers of liquid, each rated at 100 gallons, for a total of 1,200 gallons. Is this a tank vehicle under the federal definition?
Show answer
Answer B: No, because no individual container is rated above 119 gallons
The aggregate figure is reached, but the definition also requires at least one tank rated above 119 gallons, and none of these containers is.
Source: ecfr.gov
-
A truck has two permanently mounted tanks rated at 450 gallons each, 900 gallons in total. Is it a tank vehicle under the federal definition?
Show answer
Answer C: No, because the combined rated capacity is under 1,000 gallons
Each tank passes the 119 gallon test, but the tanks together fall short of the 1,000 gallon aggregate capacity the definition also requires.
Source: ecfr.gov
-
Your tank is rated far above the federal thresholds but it carries a gas rather than a liquid. Does the tank vehicle endorsement apply?
Show answer
Answer D: Yes, the definition covers material carried as a liquid or as a gas
The federal definition speaks of liquid or gaseous material, so a qualifying gas tank needs the endorsement just as a liquid tank does.
Source: ecfr.gov
-
You are sent to return a cleaned and empty 6,000 gallon cargo tank to the terminal. Do you still need the tank vehicle endorsement?
Show answer
Answer B: Yes, the endorsement depends on the tank fitted to the vehicle, not on its contents
The definition turns on the tank attached to the vehicle and its rated capacity, so an empty qualifying tank still calls for the endorsement.
Source: ecfr.gov
-
You drive a straight truck with a 2,500 gallon mounted tank of milk. Which endorsement does the job call for?
Show answer
Answer D: N, because the tank meets the capacity thresholds and milk is not a hazardous material
The tank is large enough to trigger the endorsement, and since the product is not regulated as hazardous no hazardous materials endorsement is added.
Source: ecfr.gov
-
In a turn, the liquid in your partly loaded tank runs to one side of the shell. What does that do to the center of gravity?
Show answer
Answer A: It moves toward that side and makes a rollover more likely
A load that can move carries its center of gravity with it, so the weight ends up over one side of a vehicle that is already top heavy.
-
A car pulls out in front of your loaded tank and there is room to swerve. What is the main added danger of a hard swerve in this vehicle?
Show answer
Answer C: The vehicle can roll over as the top heavy load is thrown to one side
A swerve throws weight sideways, and in a tall tank that sideways weight is what puts the vehicle over.
-
You have swerved around an obstacle in a loaded tank. When is the risk of rolling over greatest?
Show answer
Answer A: While you are steering back, as the load surges the other way
The return steer meets a load that is already moving to one side, so the second weight transfer is stronger than the first.
-
What is the safest way to change lanes on a highway with a loaded tank?
Show answer
Answer D: Signal early and move over with one smooth, gradual steering movement
A gradual change keeps the sideways weight transfer small, which is the whole point in a vehicle that carries its load high and loose.
-
You are driving an empty tank trailer in a strong crosswind. Why does the wind move the vehicle so much?
Show answer
Answer A: The tall round shell gives the wind a large surface and the vehicle is light
An empty tank keeps its full height and area but loses the weight that held it down, so the wind has a large surface and little resistance.
-
Which tank is most likely to be pushed sideways during a fast lane change?
Show answer
Answer B: One that is about half full, with plenty of room for the load to move
Weight plus room to move is the worst combination, so a tank around half full produces the strongest sideways wave.
-
You pull away from a stop with a partly loaded smooth bore tank. What does the liquid do?
Show answer
Answer C: It runs toward the rear and then comes forward again
Accelerating leaves the product behind for a moment, and the wave that piles up at the rear head then runs forward and shoves the vehicle.
-
You are stopped facing up a steep grade with a partly loaded tank and have to wait before pulling away. Why must the brakes be held firmly?
Show answer
Answer D: Because the liquid running back adds to gravity trying to roll you back
Coming to a stop on an upgrade sends the product forward and then back again, and that rearward wave works with gravity against you.
-
You turn at an intersection with a partly loaded tank and a wave reaches the side of the shell as you straighten out. What can happen?
Show answer
Answer A: The load can push the vehicle sideways and out of its intended path
A wave arriving at the side of the tank hands its momentum to the shell, which can move the vehicle across the lane just as you finish the turn.
-
Carrying the same partly loaded product, which tank gives the driver the least front to rear surge?
Show answer
Answer B: A baffled tank whose dividers slow the liquid as it passes through
Perforated dividers restrict how fast product can travel along the shell, so the wave that builds during a stop or a start is much weaker.
-
Why can a driver not avoid surge simply by filling every tank right to the top?
Show answer
Answer C: Because outage has to be left so the liquid has room to expand
The loading rules require empty space above the product for expansion, so some room for the load to move is always present.
-
You are assigned a sanitary tank of fruit juice that has no baffles inside. How should that change your driving compared with a baffled tank?
Show answer
Answer C: Brake and accelerate more gently and start slowing earlier than usual
A tank with nothing inside to restrain the product produces the strongest front to rear surge, so every input has to be softer and every stop planned sooner.
-
Your tank is divided by solid bulkheads. Why can the load still surge badly?
Show answer
Answer B: Because product in a partly filled compartment still moves inside it
A bulkhead stops product moving between compartments, but it does nothing about a compartment that is only partly filled and free to slosh.
-
Before you drive an unfamiliar tank trailer, what should you find out so you know how it will handle?
Show answer
Answer A: Whether it is baffled, smooth bore or divided into compartments
The interior arrangement decides how violently the product can move, which is the single biggest difference between one tank and another.
-
You are backing a partly loaded tank slowly toward a loading rack and stop abruptly. What can the load do?
Show answer
Answer D: It can keep the vehicle moving for a moment after the wheels have stopped
Surge does not care how slow you are going, so even at backing speed the wave can nudge the vehicle into whatever is behind it.
-
Under the federal outage rules for bulk packagings, which reference temperature applies to an insulated tank?
Show answer
Answer A: 105 degrees Fahrenheit
Insulation slows the heat reaching the product, so the rule uses a lower reference temperature for an insulated tank than for a bare one.
Source: ecfr.gov
-
What is the minimum outage when loading a bulk liquid that is poisonous by inhalation?
Show answer
Answer C: 5 percent of the total capacity
Materials poisonous by inhalation get a larger margin than the one percent used for other liquids, because a release would be far more dangerous.
Source: ecfr.gov
-
Why is outage measured at a high reference temperature instead of the temperature at the loading rack?
Show answer
Answer B: Because the tank must not become liquid full on the hottest part of a trip
The margin has to survive the worst heat the load will meet, so the rule fixes a high temperature and asks for space left at that point.
-
A dense chemical fills only part of your tank before you reach the legal weight. How should you plan the trip?
Show answer
Answer D: Expect strong surge and allow extra room for slowing and stopping
Loading to weight rather than to volume leaves a large space above the product, so the trip is made with a moving load that lengthens every stop.
-
What do you need to know about the product before you decide how many gallons to load?
Show answer
Answer B: How much one gallon of that particular product weighs
Gallons only become pounds once you know the weight per gallon, and it is the weight that has to stay inside the legal limits.
-
You have loaded a compartmented tank and the gross weight is within the limit. What should you still do?
Show answer
Answer D: Check the weight on each axle group before you leave the loading site
Compartments can put a legal total over one group of axles, so the axle weights have to be checked separately from the gross weight.
-
You load only the rear compartments of a tank trailer. Besides the axle weight limits, what else can suffer?
Show answer
Answer A: Traction at the drive axles, because weight is taken off them
Weight carried at the back of the trailer is lifted off the drive axles, and drive wheels with less weight on them lose grip for pulling and for braking.
-
Besides the maximum weight of lading, what else does the specification plate on a cargo tank tell you?
Show answer
Answer C: The specification the tank was built to and its design pressure
The plate records what the tank is: the specification it was built to, its design pressure and its capacity, which together define what it may legally carry.
Source: ecfr.gov
-
The specification plate on the cargo tank you have been assigned is missing. What does that mean for the load?
Show answer
Answer C: You cannot confirm the limits of the tank, so it should not be loaded
Without the plate there is no way to show which specification the tank meets or what its pressure and weight limits are, so it cannot be offered for loading.
-
How often must most specification cargo tanks receive a pressure retest?
Show answer
Answer A: Every five years
The pressure retest runs on a five year cycle for most cargo tanks, while shorter intervals apply to tanks in services that attack the shell.
Source: ecfr.gov
-
An unlined cargo tank is used for a material that is corrosive to the shell. How often must it be given a thickness test?
Show answer
Answer D: Every two years
A corrosive product eats away at an unlined shell, so the wall thickness is measured every two years to catch the loss before it becomes dangerous.
Source: ecfr.gov
-
The marking on a cargo tank shows 03-2026 followed by the letters V and K. What does it record?
Show answer
Answer B: That an external visual inspection and a leakage test were done then
The date is when the work was done and each letter names a test, with V standing for the external visual inspection and K for the leakage test.
Source: ecfr.gov
-
What should you check where the shell of the tank meets the frame of the vehicle?
Show answer
Answer B: That the mounting brackets and bolts are sound and nothing is loose
The mountings hold a heavy load that pushes and pulls at every stop and every curve, so loose or cracked brackets are a serious defect.
-
Why must the walkway and ladder of a tank vehicle be checked before a trip?
Show answer
Answer C: Because a loose step or spilled product can drop you from the tank top
The driver has to climb up to reach the manhole and the fittings, so a damaged step or a slick surface is a fall from the height of the shell.
-
You have finished loading and closed the tank up. What should you do before pulling away?
Show answer
Answer D: Walk around the vehicle and look underneath it for any drips
Loading is when a fitting is most likely to be left weeping, and a walk around with a look at the ground catches it before it becomes a trail down the road.
-
What must be done with the delivery hoses before the vehicle is driven away?
Show answer
Answer A: They must be disconnected, drained and secured in their carrier
A hose that is still connected or left loose can be torn off, dropped in the roadway or dragged, and any of those spills what is left inside it.
-
What is the purpose of the rollover damage protection built around the fittings on top of a cargo tank?
Show answer
Answer D: To keep the manhole and valves from tearing off if the tank goes over
If the vehicle lands on its side the guard takes the impact instead of the fittings, so the openings stay closed and the product stays inside.
-
When should the remote control for the emergency shut-off be checked?
Show answer
Answer B: Before the transfer starts, so you know it will work when needed
The one moment the shut-off is needed is the moment there is no time to find out that it does not work, so it is proved before any product moves.
-
What is the difference between bonding and grounding at a loading rack?
Show answer
Answer A: Bonding joins the tank and the fill pipe; grounding runs to the earth
Bonding puts the tank and the equipment at the same electrical potential, while grounding gives the charge a path into the earth.
-
When should the bonding wire be connected and removed when top loading a flammable liquid?
Show answer
Answer C: Connected before the dome cover is opened and removed after it is closed
The charge can jump the moment the tank is opened to the air, so the bond is made first and broken last, once everything is shut again.
-
Apart from staying close by, what else must the person attending a cargo tank during unloading be able to do?
Show answer
Answer A: Know the hazards of the material and be able to move the vehicle
Attendance is about being able to act, which means understanding the product, knowing the emergency steps and being authorized to move the tank.
Source: ecfr.gov
-
A customer asks you to come into the office to sign paperwork while your tank is still discharging. What should you do?
Show answer
Answer C: Stop the transfer or have a qualified attendant stay with the tank
The tank has to be attended for the whole transfer, so either the flow stops or a qualified person takes your place before you walk away.
Source: ecfr.gov
-
You need to move the truck a few feet at the delivery point while the hose is still connected. What should you do?
Show answer
Answer B: Do not move until the hose is disconnected and stowed away
A tank is never moved with loading or unloading connections attached, because the fitting tears out and empties the line onto the ground.
-
What has to be done before a cargo tank leaves a delivery point?
Show answer
Answer D: Valves closed, caps replaced and the manhole covers secured
Every opening used during the delivery has to be shut and secured, because whatever is left in the tank will surge against those closures all the way home.
-
How close to a tank vehicle carrying a flammable liquid may a person smoke?
Show answer
Answer C: No smoking is allowed within 25 feet of the vehicle
Federal rules keep lighted smoking materials at least 25 feet away from a vehicle carrying flammable liquids, because vapor travels well beyond the tank itself.
Source: ecfr.gov
-
When top loading a flammable liquid, why should the product be delivered down into the tank rather than allowed to splash in?
Show answer
Answer A: Splashing builds a static charge and stirs up vapor in the tank
Liquid falling freely through the vapor space generates static at the same time as it mixes air into the vapor, which is the recipe for an ignition.
-
You are running a half loaded tank on a rain soaked highway. Why is this combination worse than either problem on its own?
Show answer
Answer B: The tires have less grip at the same time as the load is pushing
Surge asks the tires for extra grip exactly when the wet surface has taken grip away, so speed has to come down further than either factor alone would suggest.
-
A partly loaded tank begins to sway from side to side on the highway. What should you do?
Show answer
Answer B: Ease off the accelerator and let the speed drop without sharp steering
Every sharp input feeds the wave that is causing the sway, so the cure is to take the energy out of it by losing speed gently.
-
You are descending a long grade with a partly loaded tank. How does surge affect your speed control?
Show answer
Answer C: Each brake application sends the load forward and pushes you on
Braking on a downgrade throws the product against the front of the tank, and that push works with gravity, so speed is held with a low gear rather than the brakes.
-
You have to swerve to avoid an obstacle in a loaded tank. How should the movement be made?
Show answer
Answer A: No larger than it needs to be, with a gentle return to the lane
The size and the speed of the steering decide how much weight is thrown sideways, so the smallest movement that clears the hazard is the safest one.