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Fluids Handling

Watson-Marlow peristaltic pump shifts thinking at Severn Trent

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A 520 DuN/REM high pressure peristaltic pump from Watson-Marlow Pumps Group has met the immediate needs of three chemical dosing schemes implemented recently at various Severn Trent Water facilities.

Deployed as part of a temporary dosing rig constructed by engineering group, Costain, the pump’s success is helping to pave the way for future consideration of peristaltic technology. Severn Trent’s historical preference has been to use conventional metering pumps.

Until recently, Severn Trent Water consistently used a specialist manufacturer of chemical dosing systems, all of which featured metering pumps,” confirms Paul Pearson, Process Commissioning Engineer at Costain. “However, in the past few months, aware that there may be even greater savings available, this arrangement has been relaxed and it’s given us the opportunity to run trials at Severn Trent using a peristaltic pump.”

Triple success

Configured by Costain as part of a portable, temporary dosing rig, the peristaltic-based system has already proved successful on three Severn Trent Water schemes.

According to Mr Pearson, there are at least a further half-dozen such applications planned for the coming 12 months, all of which will also use peristaltic technology supplied by Watson-Marlow, although some are larger schemes which might demand a higher flow rate specification than the existing 520 DuN/REM model (108 litres/hour at 4.1 bar).

The three schemes to date have seen the peristaltic pump used for ferrous chloride and ferric sulphate dosing. These coagulants bind with phosphates in wastewater so they can be removed as sludge.

The Urban Wastewater Treatment Directive has meant that water companies have to be very stringent about the level of substances such as phosphates that are recorded in treated water, hence accurate dosing is of paramount importance. The pump has also been used to dose with lime for pH correction.

In my mind there are so many things that can go wrong with a metering pump,” says Mr Pearson, “but with peristaltic, the potential for failure is reduced massively because there are no valves, stators, diaphragms, seals or glands. It makes maintenance extremely straightforward. Only the tubing requires replacement, which is quick and inexpensive, and provided this is done at the recommended intervals, there won’t be any problems. We’ve certainly had no issues so far.”

Increasingly popular

The Watson-Marlow 520REM pumphead features large swept volume with sprung rollers for high accuracy, while the NEMA 4X enclosure delivers wash-down protection for use in arduous conditions such as the wastewater industry.

Peristaltic pumps have become particularly popular because nothing but the hose or tube touches the fluid, eliminating the risk of the pump contaminating the fluid, or the fluid contaminating the pump.

The pump action is created by compressing the tube between rotating rollers and a track. In between each roller pass, the tube recovers to create a vacuum and draws in fluid.

Complete closure of the tube provides the pump with its action, preventing backflow and siphoning, and eliminating the need for check-valves when the pump is not running.

www.wmpg.co.uk

Watson Marlow
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Watson-Marlow Fluid Technology Solutions

About us

Watson-Marlow Fluid Technology Group (WMFTG) peristaltic tube and hose pumps meet requirements including: value for money; low cost of ownership; reliability and ease of maintenance to the food and beverage, chemical, pharmaceutical, mining and many other industries.

We demonstrate how pumps deliver significant process efficiencies over the lifetime of the equipment. Whether performing flavouring addition in food processing, chemical metering in water treatment or mineral recovery, we have a solution which can cut pump downtime and reduce costs through higher accuracy metering and transfer. WMFTG has dedicated application engineers available to help customers make the right pump and tubing choice from a range providing microlitres per minute to 80 cubic metres per hour flow rates.

The only part of the pump to come into contact with the product is the tube or hose. This means there are no seals or valves that can wear or fail. Replacing the tube or hose can be performed quickly and safely. Peristaltic pump benefits include:

Total fluid containment with no seals No ancillaries Handle viscous and abrasive slurries and sludge Self-priming capability Dry running without damage to the pump In addition to their range of positive displacement pumps, Watson-Marlow Fluid Technology Group has added PTFE-lined chemical and industrial hoses to their range. Aflex hoses are reinforced to withstand the most severe conditions and use.

Where we supply to

Europe, Africa, Asia, Australia, South America, North America

Industries we supply to

Automation, Chemicals, Consultants, Components Electronics, Energy and Power, Food and Beverage, Glass Ceramics Cement, Metals and Minerals, OEM, Paper and Pulp, Pharmaceutical Cosmetics Toiletries, Plastics and Rubber, Recycling, Textiles, Tobacco, Water and Wastewater

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