What defines a positive displacement pump?

Answer: C — It is self-priming and delivers a definite volume of water

A positive displacement pump is characterized by its ability to deliver a specific volume of fluid with each cycle of operation. This means that no matter the pressure in the system, the pump will move a defined quantity of water each time it completes a cycle. This is a fundamental aspect of positive displacement pumps, making them well-suited for applications that require consistent flow rates, such as firefighting, where precise water delivery is crucial. Such pumps can often handle varying pressures effectively, which may occur in different operational scenarios, providing reliable performance where consistent flow is essential. Your understanding that it is self-priming and delivers a definite volume of water reflects a key feature of many positive displacement pumps, highlighting their utility in scenarios that require dependable and measurable fluid movement. In contrast, while some pumps may need external priming or operate through centrifugal force, these characteristics do not define positive displacement pumps specifically, as they relate more to other types of pumps. The unique attributes of a positive displacement pump regarding flow consistency and pressure resilience are what make it specifically identifiable within the broader category of fluid handling devices.