A mechanical device that moves fluid by trapping a fixed amount and then forcing (displacing) that trapped volume into the discharge pipe is categorized within a specific pumping mechanism. This class of pump delivers a constant volume of fluid for each cycle of operation, largely independent of the discharge pressure. A simple example is a syringe; the plunger draws a fixed volume, and then expels it regardless of the resistance encountered (within mechanical limits).
This method of fluid transfer offers significant advantages in applications requiring precise flow rates and the ability to handle viscous fluids. The consistent volume output makes them suitable for metering and dosing processes. Historically, these mechanisms have played a crucial role across various industries, enabling advancements in areas like chemical processing, hydraulic systems, and oil and gas extraction due to their reliability and predictable performance.