NJ CDL Tanker key terms

A tank divided internally by walls with holes or openings that slow the front-to-back movement of liquid. Baffles reduce surge but never eliminate it, so a partially filled baffled tank still requires smooth braking and slow turns.

A tank with no internal dividers, so the entire load can shift from one end to the other in one motion. Surge forces are strongest in these tanks, and stopping distance increases noticeably.

The forward, backward, and side-to-side movement of liquid inside a partly filled tank as the vehicle changes speed or direction. Surge pushes the vehicle and can make it hard to steer, stop, or stay in lane.

The empty space left above the liquid in a tank, expressed as a percentage of total tank volume. It allows for expansion of the product as temperature rises and is required for safe transport.

The distance from the top of the liquid to a reference point such as the tank shell or the bottom of a gauge hatch. It is measured to determine how much room remains for expansion.

The extra space left in a tank so a product can grow in volume as it warms without overflowing. It is the reason tanks are never filled to the top, especially with heated or volatile loads.

Filling a tank beyond its permitted level, leaving too little room for expansion. Overfilling can force liquid out through vents or the dome, creating spill and fire hazards on the road.

The side-to-side motion of liquid in a partly loaded tank during turns or lane changes. It can cause a rollover by shifting weight to the outside of the curve, so turns must be made slowly.

The danger that a tanker tips over because of a high center of gravity combined with liquid movement. It rises sharply with speed in curves and with abrupt steering corrections.

The condition of carrying weight high above the road, as in a loaded tank trailer. It makes the vehicle less stable in turns and more likely to roll over than a flatbed or van.

The raised compartment on top of a tank that holds hatches, vents, and gauging equipment. The dome cover must be closed and latched before the vehicle moves.

The lid over the dome or hatch opening of a tank. It must be securely closed and sealed before driving so liquid cannot escape and vapors cannot enter the cab.

An opening in the top of a tank used to measure product level with a gauge pole or tape. Opening it can release vapors, so it must be done with care and only when required.

An internal wall that separates a tank into compartments. Bulkheads limit how much liquid can move at once and help isolate different products.

A separate section of a tank trailer divided by bulkheads, each holding its own product. Each compartment must be loaded, unloaded, and vented correctly for its contents.

A document listing the products, quantities, and compartment locations in the tank. It tells the driver and emergency responders what is aboard and where it is located.

The required paperwork describing hazardous materials being transported, including proper shipping name, hazard class, and quantity. It must be kept accessible in the cab and given to responders at an incident.

A diamond-shaped warning sign attached to the vehicle showing the hazard class of the load. Placards alert emergency responders and the public to the danger and must match the shipped product.

A category that groups hazardous materials by their primary danger, such as flammable liquid or corrosive. The class determines placarding, packaging, and emergency response requirements.

A liquid that gives off vapors able to ignite at normal temperatures. Its vapors are often heavier than air and can travel to an ignition source far from the tank.

The lowest temperature at which a liquid gives off enough vapor to form an ignitable mixture near its surface. A lower flash point means a greater fire hazard during loading and transport.

The pressure exerted by vapor above a liquid inside a closed tank. High vapor pressure means more vapor is produced, raising fire risk and the chance of pressure buildup.

The controlled release of pressure or vacuum from a tank through vents or valves. Proper venting prevents tank damage from pressure buildup or collapse during loading, unloading, and temperature change.

A system that captures vapors displaced from a tank during loading instead of releasing them to the air. It reduces fire, health, and environmental hazards and must be connected correctly before transfer begins.

Filling a tank through connections at the bottom rather than over the top. It reduces vapor generation and static buildup and is common at terminals for large tankers.

Filling a tank by dropping product in through an open hatch at the top. It creates more vapor and static, so bonding, grounding, and vapor control are especially important.

An electric charge that builds up as liquid moves through pipes, hoses, and filters. If it discharges as a spark near flammable vapors, it can cause a fire or explosion.

Connecting two pieces of equipment electrically so they are at the same potential. Bonding the tank to the loading source prevents a spark from jumping between them during transfer.

Connecting equipment to the earth so static charge drains away safely. Grounding must be in place before loading starts and kept until transfer is finished.

A valve that stops the flow of product quickly in an emergency. The driver must know its location and how to operate it at the terminal, on the vehicle, and at the delivery point.

A valve mounted inside the tank at an outlet, designed to close automatically if the external piping is damaged. It limits how much product can escape in an accident.

The procedure for stopping transfer operations and shutting off equipment when a leak, fire, or other danger occurs. Knowing the steps and the location of controls prevents injury and limits release.

Moving people away from the danger zone of a spill, fire, or vapor release. Wind direction and the product's hazards determine which way to go and how far to stay back.

The area kept clear around a tanker incident to protect people from fire, vapor, and explosion. Its size depends on the product and the size of the release, and it must be set up before approaching.

A check of the tanker before driving, covering tank shell, valves, hoses, dome covers, placards, tires, and brakes. It catches leaks, loose fittings, and damage that could cause a spill or crash.

Inspecting the tank, valves, fittings, and hoses for escaping product before and after loading. Early detection prevents spills, fires, and contamination of the load.

The ability of a vehicle to resist tipping in turns and sudden maneuvers. A tanker's roll stability is lower when loaded high, so drivers must slow down before curves.

The distance a vehicle travels from the moment brakes are applied until it stops. Liquid surge can lengthen it, so a tanker needs more following distance than other trucks.

The gap kept between a tanker and the vehicle ahead. Extra space gives time to brake smoothly so the load does not surge forward and push the truck.