A tank truck is a motor vehicle designed specifically to haul liquids or gases on public roads using a cylinder-shaped, horizontal cargo bay. There are numerous types of tank trucks on the road, differentiated by their size, what substances they transport, and how much volume they can haul.
The size of a tank truck can vary greatly, but they tend to be large and many are classified as semi-trailer trucks. The largest tank trucks, usually reserved for long hauls, that transport materials long distances can carry up to 34,000 liters (almost 9,000 gallons). Smaller versions, often used for in-town transport, may haul 11,000 liters (about 2,900 gallons) or less.
Tank trucks, also referred to as road tankers, can hold a number of different types of liquids and gases, including milk, gasoline and numerous hazardous materials. The differences between one tank truck to the next basically revolves around one thing — what it carries. The cylinders that store the gas or liquid can be insulated, pressurized, and reinforced with aluminum, carbon steel, stainless steel or fiberglass-reinforced plastic depending on the substances it transports. Some will even be fit for multiple types of substances, meaning there is an internal tank divider.
Carrying liquids, which can shift during transport and become top heavy, typically requires drivers to take corners more slowly, factor in weather and road conditions to a larger extent, and take more rest breaks during a long trip. Since hazardous materials are commonly carried, tank truck drivers have a higher set of regulations and standards to adhere to. This can include significant extra training and a requirement to hold a hazardous materials endorsement. When a tank truck is carrying hazardous materials, it will be noted in signage usually at the back of the cargo bay. These signs have a number and color that alerts emergency professionals as to what substances are on board in the case of emergency.
There are a number of common tank trucks out on the road. A good example of a larger one are gasoline transport trucks often seen refueling area gas stations. While this is perhaps the most recognized type of tank truck, many other liquid goods, such as concrete, milk, water, diesel and industrial chemicals, may be transported in these vehicles.
The smaller size of tank trucks, those with a capacity of less than 11,000 liters (about 2,900 gallons), are designed for shorter transport distances. Common examples include a septic service truck or liquefied petroleum gas carriers. These trucks often have a pumping system to service buildings and residential houses. Small tank trucks are also common at airports, transporting fuel to aircraft.