Which type of pump has a double casing?

• A. Centrifugal pump
• B. Barrel pump
• C. Submersible pump
• D. Gear pump

Answer: (B)

The correct answer is the barrel pump, characterized by its double casing design. This feature allows for better thermal insulation and protection of the internal components, as well as increased safety by preventing leaks. The outer casing acts as a protective layer while maintaining a consistent temperature, which is particularly important when handling heated or corrosive fluids. This design is also beneficial for managing viscosity changes during operation.

In contrast, the other types of pumps listed typically do not incorporate a double casing. Centrifugal pumps, for example, often have a single casing that houses the impeller and volute. Submersible pumps are designed to operate underwater, and their construction primarily focuses on water-tight integrity rather than having an additional casing. Gear pumps generally consist of a simple design with interlocking gears and a single casing to contain them. Understanding these design elements helps clarify why the barrel pump is uniquely identified by its double casing configuration.