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Home   /   Knowledge Base   /   Diaphragm Dosing Pumps: Precision Chemical Delivery For Water Treatment

Diaphragm Dosing Pumps: Precision Chemical Delivery For Water Treatment

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Article ID: KBA-25
Date: May, 2025

Effective Water Treatment

Diaphragm dosing pumps support a wide range of applications, from disinfection to pH control and nutrient delivery. Isolating aggressive chemicals from mechanical components offers a dependable solution that limits wear, helps prevent leaks, and maintains consistent performance over time. In this article, we take a closer look at how diaphragm dosing pumps work in effective water and wastewater treatment.

How diaphragm dosing pumps work

A diaphragm dosing pump is a type of water pump designed for precise chemical injection. It moves fluid by flexing a diaphragm in a sealed chamber. As the diaphragm retracts, fluid is drawn in through a one-way inlet valve.

When it extends, the fluid is pushed out through an outlet valve, which delivers a measured volume with each stroke. This design ensures long-term dosing accuracy and safely handles corrosive, hazardous, or high-purity chemicals without damaging internal components or disrupting the flow.

Common applications of diaphragm dosing pumps

Diaphragm dosing pumps are commonly used in systems that require accurate, repeatable chemical delivery. Typical applications include:

  • Municipal water treatment: Diaphragm pumps control chlorine and sodium hypochlorite dosing to maintain safe disinfection levels in drinking water supplies.
  • Mine site water management: They dose acids or alkalis into runoff and process water, helping manage discharge limits and prevent equipment damage.
  • Agricultural irrigation: Diaphragm dosing pumps deliver fertilisers and additives in fertigation systems.
  • Industrial wastewater treatment: Polymers, coagulants, and other agents are accurately dosed into tanks and pipelines without pump degradation, even with harsh chemicals.
  • Cooling towers and boiler systems: They help maintain chemical balance by injecting scale inhibitors, biocides or corrosion-control products into recirculating systems.

Functional features for safe and precise dosing

Diaphragm dosing pumps help operators manage chemical delivery accurately with features such as:

  • Stroke and frequency adjustment: This controls the amount of chemical dosed and the frequency of dosing, which is essential for matching dosing rates to system demand.
  • Chemical-resistant materials: Dosing pump heads and internal components are typically made from PVDF, PTFE or stainless steel to handle corrosive or reactive chemicals without breaking down or leaching.
  • Pressure relief and anti-siphon protection: Integrated valves prevent dosing spikes from back pressure and stop siphoning in gravity-fed lines, helping avoid unplanned chemical releases.
  • Input signal compatibility: Standard 4–20 mA and pulse input options facilitate easy connection of pumps to automated control systems. Flow-based or time-based dosing adjustments can be made remotely.
  • Degassing functionality: Optional degassing valves are used when dosing off-gassing liquids, such as sodium hypochlorite. They allow air to escape, avoiding vapour lock and interruptions in flow.
  • Double diaphragm options: For high-risk environments, some dosing pumps include a backup diaphragm and leak detection to contain failures and trigger system alerts before dosing is affected.

Talk to the water experts at Dowdens

Diaphragm dosing pumps must be matched to the specific chemical being used, the control system in place, and the on-site conditions. At Dowdens, we design systems that consider all of this from the outset, ensuring accurate, safe, and reliable chemical delivery.

Our team can help with pump selection, system design, installation support and long-term maintenance. We also supply air-operated pumps, bore-well pumps and other dosing pumps for a wide range of water treatment applications across industrial, municipal and agricultural projects. Get in touch for a suitable dosing pump solution tailored for your site.

Contact Dowdens

Featured Products

Dowdens Pumping & Water Treatment offers a wide range of Dosing Pump solutions. This extensive selection allows us to provide customised solutions for any project, supported by our industry-trained engineers, draftsmen, project managers, salespeople, and tradespeople who can design tailored solutions for various purposes.

Our experienced team is ready to help you select the right products to meet your needs. Whether you require an immediate solution or are planning for the long term, we can help you source the products necessary for a successful installation.

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Grundfos DDE 15-4 98147447 Digital Dosing Pump

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Grundfos DDA 12-10 AR-C-PVC/T/C-F-31U2U2IG Digital Dosing Pump

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Grundfos DDA 120-7 AR-PV/T/C-F-31U3U3IG Digital Dosing Pump

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Grundfos DDA 7.5-16 FCM-PVC/V/C-F-31I001IG Digital Dosing Pump

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Grundfos DDA 60-10 AR-PVC/V/C-F-31U3U3FG Digital Dosing Pump

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Grundfos DDE 120-7 99246459 Digital Dosing Pump

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Grundfos DDE 60-10 99246457 Digital Dosing Pump

Capabilities

Dowdens Pumping & Water Treatment provides comprehensive services across various industries, including tailored Asset Management, a user-friendly Document Library, and Engineering, Procurement, and Construction (EPC) services for large projects.

Our Knowledge Base aids in troubleshooting pumping and water treatment challenges, while branches in Mackay, Rockhampton, Brisbane, and Proserpine offer convenient access to workshop and field services.

Additionally, the Photo Library showcases completed projects, a skilled Solutions Engineering team for design and system servicing, and a Video Library with informative content.

Asset Management

Case Studies

Document Library

Knowledge Base

Photo Library

Solutions Engineering

Video Library

Featured Documents

At Dowdens, we are committed to providing our customers with the resources they need to make informed decisions and achieve their goals. That’s why we maintain a comprehensive Document Library brimming with valuable insights about our latest product offerings, industry expertise, and real-world applications.

Featured Videos

Dowdens has a large video library that we hope will provide insights and help you better understand how our products work and can be used. You can view our entire library by clicking on the link below.

Featured Case Studies

Looking for more information, our Case Studies provide detailed insights into various projects that Dowdens Pumping & Water Treatment has effectively managed and completed.

CS-121 – Nov 2020

Truck Stop / Service Station Water and Sewage Treatment Plant with Irrigation System

CS-133 – September 2024

Calen Township Water Treatment Plant Upgrade

CS-34 – February 2017

Coppabella Township Sewage Treatment Plant Upgrade

CS-99 – January 2020

Nebo Township Water Treatment Plant

Are you Interested in Dosing Pump Solutions?

The Dowdens Team are ready to help. Contact us today for more information and to start the conversation.

Our Locations

Dowdens has four convenient locations throughout Queensland. We have branches in Mackay and Proserpine in the north, servicing the Sugar and Coal industries, a centrally located branch in Rockhampton, specialising in the Agricultural and Coal industries, and a branch in Brisbane, servicing multiple industries in southeast Queensland.

Dowdens Mackay

Dowdens Brisbane

Dowdens Proserpine

Dowdens Rockhampton

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