Which characteristic defines a positive-displacement pump?

A positive-displacement pump is defined by its mechanism of operation, which involves trapping a fixed amount of fluid and then forcing that fluid out into the discharge pipe. This characteristic sets it apart from other pump types that may rely on the velocity of the fluid or the pressure to move it.

In a positive-displacement pump, the movement of the fluid occurs in a series of distinct, fixed volumes. As the pump operates, it creates a chamber in which it draws liquid during one portion of its cycle. Once that chamber is filled, the pump then expels that same fixed volume of fluid during the next phase of operation. This method of pumping is particularly effective in creating a constant flow, regardless of downstream pressure variations.

This mechanism enables positive-displacement pumps to perform efficiently across a range of applications, especially where fluids are viscous or where precise flow control is needed. Understanding this principle is crucial for anyone designing plumbing systems or selecting pumps for specific applications, as it impacts performance and suitability based on the requirements of the system.