New Qdos 20 optimises metering for sodium hypochlorite applications

Qdos 20 pump

The new Qdos 20 pump – an extension to the popular Qdos range – has been launched by Watson-Marlow Fluid Technology Group. 

The new pump has been developed to offer highly accurate sodium hypochlorite metering in disinfection applications with flow rates to 20 litres per hours at a maximum of 7 bar pressure. It is especially suitable for applications at the well sites of many smaller water treatment plants, where operators are often injecting into water lines at higher pressure.

Qdos 20 features the same user-friendly interface and control options, ensuring that users have continuity with any existing Qdos applications.  Offering low total cost of ownership, the new model is designed as a drop-in replacement for diaphragm pumps. Qdos pumps also include the ReNu pumphead for single, no-tools maintenance. 

Its intuitive interface provides simple control of the pump via manual, 4-20mA, contact or PROFIBUS control.  The brushless DC motor control maintains flow accuracy of +/-1% with a repeatability of +/-0.5% and a turndown ratio of 3330:1.

The pump is ideally suited for tight control for chlorine residual. Successful field trials and SCADA data indicate a considerable improvement in variation of chlorine residual compared to even the highest specification diaphragm metering pumps. This is achieved via the twin offset rotor design.  

The Qdos 20 peristaltic pump technology uses two tube channels; where the channels are operated out of phase.  Although peristaltic pumps are generally lower in pulsation than other positive displacement pumps, Qdos 20 reduces this pulsation even further by alternate tube compressions ensuring pulsation is balanced out.  This results in almost continual positive fluid displacement, and consistent metering of chemical into the application.  

Process uptime is maximised by facilitating quick, safe and easy pumphead removal and replacement, with no need for tools, no specialist training and no maintenance technicians needed on site. The contained pumphead design with integral leak detection reduces wastage and eliminates operator exposure to chemicals.

Field trials have confirmed the long life of the pumphead, with one utilities customer in Minneapolis experiencing 12 months pumphead life. When operating up to 7 bar, the Qdos 20 pump also significantly reduced maintenance downtime. As a result, the plant is currently in the process of replacing the trial model with a production unit. 

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