Final answer:
Hot oil pumps are typically single stage centrifugal pumps, designed to handle high temperature heat transfer oils used in thermal fluid heating systems.
Step-by-step explanation:
Typically, a hot oil pump that is used in thermal fluid heating systems, particularly for transferring heat transfer oils that can operate at high temperatures, is a single stage centrifugal pump. Centrifugal pumps are chosen for their ability to handle high temperatures and the thermal stability of the fluids they are moving without significant thermal expansion issues.
They often have features such as a cooled shaft seal and special materials to withstand the heat. Three stage centrifugal pumps are more commonly used for high pressure applications, not specifically for high temperature fluids.
A differential pressure pump is typically involved in applications that require a specific pressure differential, not just for handling heat transfer fluids. Discharge refers to the outflow of a pump rather than a type of pump, so option 4 is not a type of pump at all.