At the well sites of many smaller water treatment plants, operators often need to inject disinfection chemicals into waterlines at high pressures. The Qdos 20 peristaltic metering pump from Watson-Marlow Fluid Technology Group is a fit for those applications.

The pump offers accurate sodium hypochlorite metering in disinfection applications with flow rates to 5.3 gph at a maximum of 100 psi. It is designed as a drop-in replacement for diaphragm pumps and includes the ReNu pump head 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 plus or minus 1 percent, with a repeatability of plus or minus 0.5 percent and a turndown ratio of 3,330-1.

The pump is ideally suited for tight control of chlorine residual, according to the maker. 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. It comes with manual, analog, or contact mode functionality, with an intuitive 3.5-inch color display. It comes in a watertight, dustproof enclosure with an IP66 rating and can be operated in temperatures ranging from 41 to 104 degrees F.

The pump employs two tube channels operated out of phase. Although peristaltic pumps are generally lower in pulsation than other positive displacement pumps, the Qdos 20 reduces this pulsation even further using 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 maximized by facilitating quick, safe, and easy pump head removal and replacement with no gas-locking; no valve blocking; and no need for tools, special training and maintenance technicians on site. The contained pump head design with integral leak detection reduces waste and eliminates operator exposure to chemicals.

Field trials have confirmed the long life of the pump head, with one utility in Victoria, Minnesota, experiencing 12 months pump head life. “Water applications need a reliable feed for chemicals, and it is especially important to keep sodium hypochlorite running,” says Clark Corbett, sales engineer for Vessco, the city’s chemical feed equipment supplier. “Smaller towns tend to have limited maintenance personnel. With this technology, they only need to periodically replace the pump head.” 800-282-8823; www.wmftg.com