Chemical Metering Pumps
Chemical metering pumps are used to dispense virtually any liquid such as chemicals and acids, as well as viscous liquids and suspended solids, with precise accuracy. Used in applications for municipal and industrial markets, chemical pumps are found in waste water and municipal water treatment facilities, swimming pools, industrial process water, as well as packaging systems and dosing systems.
There are three basic parts to a chemical metering pump: a pump head, a piston, and an electric motor. The liquid typically goes into the pump head through an inlet line. A motor, typically a small electric motor, is used to drive the piston which helps to move the liquid through the pump head into an outlet line. When the piston moves out of the pump chamber, a vacuum is created which pressurizes the liquid in the chamber and causes it to move. The inlet and outlet valves only allow liquid to travel in the desired direction and prevent backflow and contamination of the pumping system.
In some pumps, a pressure relief valve is inserted to prevent the buildup of pressure and potential damage to the system if the liquid flow is stopped for some reason. Further precautions can be taken in metering equipment with a leak detection system and external alarm and shutoff switch in the event of liquid leakage.
As some of the liquids handled by chemical metering pumps are acidic or caustic, it is always important to check for chemical compatibility of the materials before determining the specifics of a pump. Components can be added to help calibrate a liquid pump, ensure the maintenance of pressure and prevent siphoning from a system. Various operating options for chemical metering pumps exist to further adjust the system to specific requirements. They can be constructed with manual or automatic operation control which will be determined by the nature of the pump’s application.
The pump system can be totally enclosed or partially enclosed, and the materials commonly used to make the housings are high-strength polymers such as PVC, PVDF or polypropylene, or in some cases aluminum or stainless steel can be used, depending on the liquid or chemical being dispensed. Due to the often harsh chemical environments, chemical metering pumps are typically constructed to be rugged and reliable. While maintenance is important, simple metering systems should be fairly low maintenance due to the minimal parts. However, especially in applications where liquid dispensation is continual, heavy duty pumps will be required.