Metering Pump Introduction
A metering pump is a pump that is intended to move liquids at very specific flow rates. The flow rate of most of these pumps can be set and regulated using hand dials or touch pads. Due to the nature of the application of the metering pump, the flow rates are normally very low, with most having flow rates rated in terms of gallons per hour rather that gallons per minute like in most of the other pumps.
The most common types of metering pumps are diaphragm pumps. The diaphragm is either mechanically actuated or hydraulically actuated, while in others the diaphragm is moved through a solenoid. Nevertheless, other kinds of positive displacement pumps like peristaltic pumps, piston pumps, plunger pumps and various types of rotary pumps can also act as metering pumps.
Metering pumps typically work within these ranges: Flow rates generally range from 0.001 gallons per hour to about 20 gallons per hour. The total head (pressure) generally ranges between 10 psi and 30,000 psi, while horsepower generally ranges from 0.125 to 5 horsepower.
How it Works
The metering pump works using two main mechanisms. Both mechanisms can regulate the flow rates using a variety of different pumping mechanisms. A metering pump that uses variable displacement regulates the flow by altering the amount of liquid going through the pump, while its motor is always operating at a regular speed. They mostly adjust flow rates while maintaining a regular motor speed by regulating the stroke length. In other instances, they adjust flow rates by adjusting the volume of hydraulic fluid that is circumvented or bypassed. On the other hand, a metering pump that used fixed displacement mechanism regulates the flow rate by altering the motor’s speed. While doing this, a similar volume of liquid is displaced with every revolution.
The metering pump is generally used in cases where the flow rate of a fluid being pumped needs to be constantly measured and regulated to very specific levels. The pump is normally used in pumping water treatment chemicals or pumping chemicals in drinking water and swimming pools. It is also used in pumping chemicals such as coolants in cooling towers and boilers, or in wastewater treatment facilities. The chemicals are pumped into the water to regulate the water’s alkalinity or pH and also to disinfect the water.
The metering pump is also used for blending liquid ingredients in food processing applications and in process applications that require one chemical to be mixed with another substance in exact amounts.