The positive displacement metering pump is generally the first choice for providing precise and repeatable flow in many medical device fluid-dispensing applications. Liquids ranging from test samples to reagents and wash fluids may be transferred, dispensed, or metered, depending on the application. As devices are designed to process smaller and smaller volumes of fluids, the requirements for precise metering pumps become greater. This article describes established and new metering pump technologies to enable manufacturers to select a suitable pump to meet the fluid-handling needs of a given application.
Many medical devices pump fluids.
Fluid transfer is sometimes accomplished using either centrifugal or positive displacement pumps. Centrifugal pumps transfer energy to a fluid through a spinning impeller, converting the impeller energy to fluid pressure, which moves the fluid. Because these types of pumps are pressure and fluid dependent, they are not typically used for metering because they cannot maintain precise flows under changing inlet and discharge conditions. They do, however, provide high flow rates at low pressures. Positive displacement pumps trap a fixed volume of fluid and move this fluid by means of gears, pistons, diaphragms, vanes, or other devices.