Dosing Metering Pump

HAOSH dosing metering pumps are reciprocating positive displacement pumps that provide the highest possible metering accuracy. Ensuring minimal chemical consumption but optimal disinfection. The interface integrates the pump into an automated process.

Each metering pump manufactured by HAOSH offers special advantages: high energy efficiency, low maintenance costs and very long diaphragm life. All types of needs can be met in industries such as water and wastewater treatment, oil and gas, chemical, pharmaceutical and biotechnology, food and beverage.

What Is A Chemical Metering Pump?

Metering pump, also known as dosing pump, quantitative pump or proportional pump, is a positive displacement chemical metering device capable of changing the volume manually or automatically according to the needs of the process. It is mainly used for precise injection of chemicals, such as acids, bases, corrosive or viscous liquids. Common demand occasions are as follows:

  • Requires precise metering of fluids
  • Low flow rates in ml/hr or GPH are required
  • Flow rates vary and are controlled by a computer, microprocessor, DCS or PLC
  • Handles corrosive, hazardous or high temperature fluids
  • Need to pump viscous fluids or slurries

how does a Chemical dosing pump work?

The motor of the pump drives the worm through the coupling and makes the main shaft and eccentric wheel to make rotary motion by decelerating the worm gear, and the eccentric wheel drives the sliding adjustment seat of the bow-type connecting rod to make reciprocating motion. When the plunger moves to the back dead point, the pump cavity gradually forms a vacuum, the suction valve opens and the liquid is sucked in; when the plunger moves to the front dead point, the suction valve closes and the discharge valve opens, the liquid is discharged when the plunger moves further.

In the pump’s reciprocal cycle of work to form a continuous pressure, quantitative discharge of liquid. At the same time to complete the transport, measurement and regulation of the function.

Types of metering pumps

There is a wide range of dosing pumps with a wide range of capacities. From a few milliliters (for laboratory use) to 35,000 liters per hour (for industrial engineering).

Depending on the overflow section:

  • Diaphragm metering pumps
  • Hydraulic diaphragm metering pumps
  • Plunger metering pumps
  • Peristaltic pumps

Classification by pump drive:

  • Electromagnetic driven metering pumps
  • Motor-driven metering pumps

According to the working mode:

  • Reciprocating type 
  • Rotary type
  • Gear type



Metering pump is also called quantitative pump or proportional pump. It is a special volumetric pump that can meet the needs of various strict processes and the flow rate can be steplessly adjusted in the range of 0-100% to convey liquids (especially corrosive liquids).

Dosing pumps are mainly used for quantitative delivery of acid and alkali chemicals in chemical plants, sewers, sewage treatment, and factory wastewater. For example, disinfection by dosing chlorine in drinking water treatment.

  1. Operation safety, mechanical drive diaphragm.
  2. Good sealing, no leakage, simple and safe assembly and maintenance.
  3. Can transmit high viscosity media, corrosive liquids and dangerous chemicals.
  4. Flow adjustment can adjust the stroke length or motor frequency.
  5. Diaphragm for multi-layer composite structure pressed, can enhance the use of efficiency.

Metering pumps are used to control and convey the amount of fluid passing through the pipeline. Dosing pumps also provide a controlled volume of fluid, but focus on chemical addition. They are two names for the same product.

Does not belong, metering pumps belong to the volumetric pump, and centrifugal pumps belong to the vane pump, not a class.

Motor-driven metering pumps have motors, while solenoid-driven metering pumps do not have motors.

It has a certain self-priming ability, compared to professional self-priming pumps with a weaker suction range, and the structure principle can be considered as a self-priming pump, but most of the time it is not treated as a self-priming pump.

It is usually placed above the dosing tank. In some special cases, a base can be set on the perimeter wall to place the dosing pump on the wall.

The accuracy of the metering pump involves the following three aspects during operation.

  1. Steady-state accuracy: ±2% of the rated flow rate. If the actual measured 100% stroke flow of metering pump inverter water supply equipment is 1000 L/h, the allowable deviation of steady-state accuracy is ±2% * 1000 = ±20 L/h.
  2. Linear accuracy: ± 3% of the rated flow rate, if the measured 100% stroke flow rate of the metering pump is 1000 L/h, the allowable deviation of linear accuracy is ± 3% * 1000 = ± 30 L/h.
  3. Repeat accuracy: ± 3% of the rated flow rate, if the measured 100% stroke flow rate of the metering pump is 1000L/h, the allowable deviation of repeat accuracy is ± 3% * 1000 = ± 30L/h.

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