Chemical Metering Pump Introduction
A chemical metering pump is a type of positive displacement pump. It is often used in dosing chemicals and it can adjust capacity either automatically or manually depending on the process conditions requirements. The pump features a very high level of repetitive accuracy and it has the capacity to pump a wide variety of chemicals including bases, acids, slurries, corrosive, and viscous fluids.
The pump is designed to move fluids at very precise flow rates and unlike other pumps where flow rates are rated in gallons per minute, flow rates are usually rated in gallons per hour.
How it Works
The most common type of the chemical metering pump is a diaphragm pump, which is either hydraulically actuated or mechanically actuated, while in other types, the diaphragm is flexed through a solenoid. Besides, other types of positive displacement pumps such as piston pumps, peristaltic pumps, plunger pumps, and some types of rotary pumps also qualify as chemical metering pumps.
The pumping action in a chemical metering pump is generated by a reciprocating piston which can either be in direct contact with the process liquid, or is separated from the process liquid by a diaphragm. The diaphragm is actuated by the hydraulic liquid between the diaphragm and the piston.
Chemical metering pumps regulate flow rates using two main pumping mechanisms. The first mechanism is variable displacement, whereby the flow is regulated by varying the amount of fluid passing through the pump as the motor always rotates at a constant speed. This is achieved by varying the stroke length, or the quantity of hydraulic fluid that is bypassed.
The other mechanism is fixed displacement. In a chemical metering pump that uses this mechanism, flow rates are regulated by changing the speed of the motor. As this action is performed, the same volume of fluid is displaced with each revolution.
Applications of Chemical Metering Pump
The chemical metering pump is generally used in a wide range of applications where the following conditions exist: It is used where low flow rates are required, usually in milliliters per hour or gallons per hour. It is also ideal for conditions where high system pressure is present and high accuracy feed rates are required. The chemical metering pump is suitable in conditions where dosing of chemicals is regulated by computer, microprocessor, PLC, DCS, or flow proportioning. Additionally, the pump is ideal in conditions where corrosive, viscous fluids, slurries, or hazardous high temperature fluids need to be pumped.