Diaphragm Dosing Pumps
Diaphragm dosing pumps are the most commonly used dosing systems in the water distribution, chemical, pharmaceutical and food sectors.
Typical Range of Application
- Flow Rate Range
From as low as 0.1 liters per hour (L/h) to 1000 litres per hour (L/h) or more, depending on the specific model and application. - Pressure Range
Typically up to 20 bar (290 psi) for standard models.
For High-Pressure Models, Specialised high-pressure diaphragm dosing pumps can handle pressures up to 200 bar (2900 psi) or higher. - Accuracy:
Regularly from ±1% to ±2%
For High-Precision Models, the accuracy is around ±0.5% to ±1%, and can be lower.
How Does the Dosing Diaphragm Pump Work?
There are 3 main types of dosing diaphragm pumps:
- Selenoid Spring Return
- Cam-Drive Spring Return
- Crank Drive
Selenoid Spring Return
In smaller dosing diaphragm pumps, the diaphragm is actuated by a connecting rod linked to an electromagnet. This configuration ensures that the coil receives the precise number of strokes required. The minimum dosing is determined by a single stroke of the solenoid, corresponding to the full volume of the diaphragm chamber.
Cam-Drive Spring Return
For larger dosing diaphragm pumps, the diaphragm is typically mounted on a connecting rod that is activated by a camshaft. The camshaft is driven by either a standard asynchronous motor. Flow adjustment is achieved by varying the stroke length, the frequency of the strokes, or both. To extend the operating range, frequency converters can be connected to these larger diaphragm pumps.
Crank Drive
Another type of diaphragm pump features a diaphragm activated by an eccentrically driven connecting rod, powered by either a stepper motor or a synchronous motor. Utilizing a stepper motor drive enhances the pump’s dynamic range and significantly improves its accuracy. In this design, adjusting the pump’s stroke length is unnecessary as the connecting rod is mounted directly on the diaphragm. This results in optimised suction conditions and superior operational characteristics.
This design allows for straightforward control of both the suction and discharge sides of the pump. Compared to traditional electromagnetic-driven diaphragm pumps, which produce powerful pulsations, stepper motor-driven diaphragm pumps enable a much steadier dosage of the additive. This results in more precise and consistent dosing performance.
Benefits of Dosing Diaphragm Pumps
Diaphragm dosing pumps really are the top of the dosing pump family.
Let me explain in more detail the various features and the benefits they bring.
- High Accuracy and Precision
Delivers accurate and consistent flow rates, essential for dosing and metering applications.
Easily adjustable to provide precise dosing volumes. - Chemical Compatibility
Most models are manufactured from corrosion resistant materials, suitable for handling aggressive and corrosive fluids.
Capable of handling a wide range of chemicals, including acids, bases, and solvents. - Reliability and Durability
Robust construction and high-quality materials contribute to a long service life.
Requires minimal maintenance compared to other pump types, reducing downtime and maintenance costs. - Safe Operation
The hermetically sealed diaphragm prevents leaks, ensuring safe handling of hazardous and toxic chemicals.
Capable of operating at high pressures, ensuring efficient fluid transfer in demanding applications. - Flexibility
Suitable for various industries, including water treatment, pharmaceuticals, food and beverage, and chemical processing.
Available in a range of sizes and capacities to meet different application needs. - Ease of Integration
Easily integrated into existing systems with minimal modifications.
Often comes with advanced control options, including electronic controllers and programmable settings. - Self-Priming Capability
Self-priming feature simplifies the start-up process and ensures smooth operation without the need for additional priming equipment. - Environmental Benefits
Precise dosing minimises chemical waste, contributing to environmentally friendly operations.
Hermetically sealed design reduces the risk of chemical emissions and environmental contamination.
SPS Pumps is There to Help
Dosing Pumps are critical to many businesses.
At SPS Pumps, our Centre of Excellence is there for you, to help finding the best dosing pump for your application, even in the most complex cases.
Our expertise is second to none.
Call us now at +32 2 657 23 53 or send us an email at info@sps-pumps.com
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The content of this webpage is inspired by the Grundfos Pump Handbook, including the accompanying charts.
