What type of cargo tank has an inner tank with an outer shell under vacuum?

• A. Pressure tank
• B. Cryogenic cargo tank
• C. Nonpressure tank
• D. Insulated tank

Answer: (B)

The correct answer is that a cryogenic cargo tank has an inner tank with an outer shell under vacuum. This design is specifically intended for transporting materials at extremely low temperatures, such as liquefied gases like liquid oxygen or liquefied natural gas. The inner tank holds the cryogenic liquid, while the outer shell serves as insulation to minimize heat transfer and prevent the contents from warming, which could lead to vaporization.

The vacuum between the inner and outer tank is crucial because it acts as an insulating barrier. Without it, heat could easily conduct through the walls and cause the thermal energy of the cargo to rise, which could compromise the safety and integrity of the cryogenic materials. This type of cargo tank is engineered to maintain low pressures and temperatures, ensuring that the cryogenic substances remain in a liquid state during transport.

In contrast, other types of cargo tanks, such as pressure tanks, are designed to handle higher pressures and typically do not utilize a vacuum insulation system, while nonpressure tanks and insulated tanks serve different purposes related to their specific cargo types and conditions.