Some pumping jobs are about volume; dosing is about precision. A dosing pump injects an exact, measured amount of liquid, almost always a chemical, into a process stream, tank or pipeline, and keeps doing it accurately whatever the pressure or temperature does. Water treatment, chemical processing, food and beverage, pharmaceutical production and pool maintenance all depend on getting that dose right.
We supply dosing pumps from ProMinent, one of the world’s leading names in dosing technology, and can source other makes for a specific requirement. The ranges are below, or call +44 1332 913500 for help choosing.
A dosing pump, also called a metering pump or chemical injection pump, delivers a controlled volume of liquid per stroke or per unit of time. Where a transfer pump simply moves bulk liquid from one place to another, a dosing pump’s whole purpose is accuracy: the right amount of chemical, at the right rate, regardless of what the rest of the system is doing.
They are positive displacement by design. Each stroke shifts a fixed, known volume, so the dose is set by adjusting stroke length, stroke speed or both. That gives control over rates from fractions of a millilitre an hour up to hundreds of litres an hour depending on the model.
Mechanical dosing pumps, also known as mechanically actuated diaphragm pumps, use a motor-driven cam or eccentric to push the diaphragm to and fro. The dose is set by stroke length, usually on a manual knob, and stroke frequency. Robust and simple, a mechanical dosing pump suits steady-state duties where the rate rarely changes, which is why it is so common in water treatment, cooling towers, boiler houses and pool plant.
Electronic solenoid dosing pumps drive the diaphragm with an electromagnetic solenoid and control the dose electronically. That allows remote adjustment, proportional dosing tied to a signal such as 4 to 20 mA or a flow-meter pulse, and integration with SCADA or BMS. They suit duties where the rate has to respond to changing conditions: pH correction, residual disinfection, proportional chemical feed.
Motor-driven diaphragm dosing pumps step up to higher flows and pressures than a solenoid can manage, using a geared motor through a mechanical linkage with electronic stroke control, for industrial water treatment, chemical processing and high-pressure injection.
Since the great majority of dosing pumps inject chemicals, the term chemical dosing pump is used interchangeably with dosing pump. The chemicals span the harmless to the savage, from sodium hypochlorite for pool disinfection to concentrated acids, alkalis, polymers and oxidisers in industrial treatment.
That makes compatibility critical. Every wetted part, the diaphragm, valve balls, valve seats, seals and pump head, has to resist the dosed liquid. Common materials are polypropylene, PVDF, PVC, PTFE and stainless steel. ProMinent publishes detailed chemical resistance data, and we can advise on the right combination for your fluid.
Three things size a dosing pump: the dose rate at the duty point in litres per hour, the discharge pressure it works against (back-pressure plus any static head), and the chemical being dosed, which decides the wetted-part materials. Beyond that, consider whether the rate is fixed or variable, whether the pump must accept a control signal, whether ATEX rating is needed for a hazardous area, and the power supply.
As experienced dosing pump suppliers we work mainly with ProMinent and source other makes where a job calls for it. Tell us the application on +44 1332 913500 and we will recommend the right model.
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A dosing pump injects precise, measured volumes of liquid, usually a chemical, into a process stream, tank or pipeline. Common applications include water and wastewater treatment, swimming pool chemical dosing, cooling tower treatment, food and beverage processing, and pharmaceutical manufacturing. Any process that requires a controlled, repeatable dose of liquid is a candidate for a dosing pump.
A mechanical dosing pump uses a motor-driven cam or eccentric to move the diaphragm, with dose rate adjusted manually via a stroke-length knob. An electronic dosing pump uses a solenoid to drive the diaphragm, allowing remote adjustment, proportional dosing linked to a control signal (4–20 mA, pulse input), and integration with SCADA or BMS systems. Mechanical suits steady-state duties; electronic suits have variable or responsive dosing.
A chemical dosing pump is a dosing pump used specifically to inject chemicals into a process. The term is used interchangeably with “dosing pump” across the industry. The key consideration is chemical compatibility, the pump’s wetted parts (diaphragm, valves, seals, pump head) must resist the chemical being dosed. Common wetted-part materials include PP, PVDF, PVC, PTFE and stainless steel.
Sizing requires three inputs: the dose rate you need (litres per hour), the discharge pressure the pump must work against (system back-pressure plus static head), and the chemical being dosed (which determines material selection). The pump’s maximum capacity should exceed the required dose rate by at least 10–20% to avoid running permanently at full stroke. Send us your application details and we’ll specify the right model.
Modern diaphragm dosing pumps from manufacturers like ProMinent typically deliver accuracy of ±1–2% of the set dose rate under steady-state conditions. Accuracy depends on correct installation, proper priming, and appropriate valve and tubing sizing. Degassing valves should be fitted where the dosed chemical is prone to off-gassing.
With correct chemical compatibility and routine maintenance, a quality dosing pump typically lasts 10–15 years. The diaphragm is the main wear item and is usually replaced every one to three years, depending on the chemical and duty cycle. Valve balls and seats are also periodic replacement items. Stocking a small spares kit is good practice for critical dosing duties.
