Sodium hypochlorite is used in wastewater treatment to kill off bacteria before being discharged back into the environment, and in water treatment as one the primary methods of drinking water disinfection. It is also a challenging product to pump, because it tends to off-gas, causing some types of pump to vapour lock. Diaphragm pumps are particularly prone to this.
After evaluating several pump choices from a number of manufacturers, engineers from the city of Eagan in North Minnesota, USA, chose ten Verderflex VF10 peristaltic hose pumps, which will be put to immediate use in this new area of the treatment plant. Peristaltic pumps are the pump choice for dosing sodium hypochlorite, and each Verderflex VF10 pump is capable of flow rates up to 48 US GPH and at pressures up to 175 psi. Peristaltic efficiency
In the pump, the fluid being dosed is kept totally enclosed within the rubber hose which is then compressed by a rotating shoe forcing the liquid along. Upon restitution of the hose the resulting vacuum draws in more liquid. This process is known as peristalsis and is what makes the peristaltic pump the first choice for liquid metering. Variations in hose type allow for low strength and even high strength sodium hypochlorite dosing.
The nature of the pumping process used by peristaltic pumps results in only the hose coming into contact with the fluid being pumped. Not only does this mean that the pump is hygienic and leak free, it also means that there are no moving parts to become clogged or damaged. The only maintenance required is to change the hose which is done quickly and efficiently, keeping downtime to an absolute minimum.
The wastewater plant needs to run as cost efficiently as possible and the City of Eagan engineers were impressed with the long life given by the Verderflex hose and the ease of maintenance when the hose needed to be changed.
“We were really pleased with the installation at the treatment plant,” explained Tom Eisemon, national sales manager of GPM Pumps, the master distributor for Verderflex in the US. “As a result of this installation, a similar project located nearby chose Verderflex for these same reasons and a third customer in the state recently purchased a new Verderflex DURA after hearing all the positive feedback and the new features of this design.”
