Image Credit: Mahr Metering Systems Corporation | Waston Marlow Pumps Group
Dosing pumps are low-volume pumps with controllable discharge rates that are used to inject additives or difficult-to-mix fluids into mixing, pumping, or batch/tank systems. Dosing pumps are usually made from plastic, thermoplastic, or stainless steel and feature mounting holes or accessories. Dosing pumps often have a controller which enables the fluid flow to be monitored and adjusted easily.
Dosing pumps can operate based on the principles of dynamic pumps or positive displacement pumps depending on the design. Dynamic pumps produce a variable flow suited for generating high flow rates with low viscosity fluids, while positive displacement pumps produce a constant flow suited for producing high pressures (and low flow rates) with high viscosity fluids. Most dosing pumps are positive displacement pumps, which provide steady, low flow for a variety of types of media. Look to GlobalSpec's Pump Types page for a complete guide to the different types of pumps available.
Matching a pump to the application requirements requires an analysis of manufacturer specifications. Typical specifications to consider when selecting dosing pumps are flowrate, pump head, pressure, horsepower, power rating, and operating temperature. More information on these specifications and how to interpret them can be found in GlobalSpec's Pump Flow page.
One important specification that is largely specific to dosing pumps is accuracy. Accuracy describes how close a volume of pumped fluid is to the exact desired value. Pumps with higher accuracy will pump measured volumes of fluid with more precision and repeatability. Accuracy is given in a +/- value or % variability.
The base material of a dosing pump is important to consider, as it affects the type of media that can be handled effectively. System fluids may be abrasive, acidic, caustic, tacky, very hot, very cold, or otherwise hazardous. Base materials such as cast iron, plastic, and stainless steel possess different advantages for handling these various characteristics.
- Plastics are the least expensive base materials, and provide excellent corrosion resistance and protection from a broad range of chemicals.
- Stainless steel alloys provide excellent protection against various chemicals and rust corrosion, and have higher pressure ratings than most plastics.
- Cast iron provides excellent strength and abrasion resistance, with high pressure ratings.
For more information on materials and other pump features, visit GlobalSpec's Pump Features page.
Dosing pumps are used in a variety of commercial, industrial, municipal, and maritime applications. Examples include agriculture and horticulture, dairy farms, breweries and distilleries, construction, food service and food processing, power generation, and oil and gas production. Dosing pumps are also used in the aerospace and defense, automotive, machine tool, mining, medical, pharmaceutical, semiconductor, and paper industries.
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Hydraulic pumps deliver high-pressure fluid flow to the pump outlet. Hydraulic pumps are powered by mechanical energy sources to pressurize fluid.
Magnetic Drive Pumps
Magnetic drive pumps are sealless pumps that use a coaxial magnetic coupling to transmit torque to an impeller. A standard electric motor drives a set of permanent magnets that are mounted on a carrier or drive assembly.
Plastic pumps are designed to move fluids that would corrode or damage other types of pumps. They provide broad chemical resistance and are less costly and lighter in weight than metal pumps.
Positive Displacement Pumps
Positive displacement pumps use a mechanical force such as gears, bladders, pistons, plungers or diaphragms to push liquid through and out of the pump.
Sanitary pumps are used to transport and meter solutions, slurries, and colloids of food and agricultural materials in operations such as food processing that require cleanliness. There are four basic types of sanitary pumps: centrifugal, positive displacement, jet, and airlift.
Infusion or withdrawal syringe pumps provide high pressure and high accuracy for applications such as high performance liquid chromatography (HPLC). Used to deliver precise amounts of fluid at specific time intervals.