A peristaltic metering pump is a type of positive displacement pump. When in operation, fluid is pumped through a flexible tube. Furthermore, it has rollers attached to a rotor that is controlled by a motor. This works that as the rotor turns, the rollers pinch the tubing to force the fluid through. When the tube is not compressed, the fluid flow is brought into the tube.
Peristaltic metering pumps are best suited for pumping dirty fluids that contain particulate matter. The absence of check valves that clog in the peristaltic pumps make it easy to pump the water into lower pressure systems. Furthermore, the forces that occur as the pumping process continues do not damage delicate fluids within the tube.
These pumps are also especially effective at pumping fluids that contain trapped gases. Fluids such as chlorine and hydrogen peroxide tend to release absorbed or occluded gases. This is when subjected to a vacuum or to changes in temperatures.
On the other hand, while peristaltic pumps work best under maximum pressure, they are usually limited to maximum discharge pressures of around 125 pounds per square inch (psi). As such, they can inject into a vacuum without metal spring-loaded valves. Notably, their output volume is independent from the system pressure.
When in use, the pump operator must be aware that constant squeezing of the tube degrades it over time, slowly diminishing the feed rate. This is because most manufacturers rate tubes in hours. As such, the end user must keep track of how many hours the pump has been running.
Failure to change pump tubes and service the injection point on a regular basis results in leakage from the pump tube. It is also important to ensure that the pump tube materials, including the wetted parts are compatible with the chemicals being injected. This information usually comes with the pumps, since manufacturers list the materials that make up the wetted parts.
Furthermore, modern peristaltic pumps have more tubing options and as such offer more chemical resistance and longer tube life than in the past.