When Prelok encountered problems using both impeller and diaphragm pumps to circulate adhesive coating fluids at its Willenhall plant in the West Midlands, this specialist in the application of pre-applied locking and sealing processes for threaded components turned to 521 Series pumps from Watson-Marlow. Used in combination with Gore Style 400 high-resilience tubing, the solution overcame problems caused by previous pumps of damaging the fluid, or of the fluid damaging the pump.

Prelok provides a range of high-specification pre-applied thread locking and sealing products that are used throughout the automotive, IT, construction and telecommunications sectors. Established in 1969 in the West Midlands, Prelok now has additional facilities in France, Spain and Germany that help generate annual turnover in the region of £7.5 million. The company can process threaded components that range from miniature items for mobile communications through to M30 bolts used in bridge construction.

“Our strengths lie in our ability to help customers source or manufacture quality components, quickly processing them and providing logistic solutions,” says Andy Jones, site services manager and maintenance co-ordinator at the 75-employee company. “When we have a problem in production we apply all our energies into finding a rapid and suitable solution.”

One such problem involved a process that re-circulates adhesive coating fluids prior to application. These fluids can be water or solvent-based, with the exact make-up dependent upon customer requirements.

“The problem focused on micro capsules that are suspended in the adhesive coating fluid,” explains Mr Jones. “We found that impellor pumps damaged the capsules, while a subsequently installed diaphragm pump could not work with the sometimes small amount of fluid that is present. Furthermore it was hard to get the specific diaphragm material, which is resistant to some of the aggressive chemicals we use.”

Fortunately Mr Jones recalled using Watson-Marlow peristaltic technology successfully in another process. In peristaltic pumping operations, nothing but the hose or tube touches the fluid, eliminating the risk of the pump contaminating the fluid, or the fluid contaminating the pump. Fluid is drawn into the pump, trapped between two rollers and expelled. The complete closure of the tube gives the pump its positive displacement action, preventing backflow and eliminating the need for check valves when the pump is not running.

A Watson-Marlow 521 Series pump was duly installed at Prelok’s Willenhall factory where it successfully overcame the previous problems encountered. So impressive was its performance that the company now has a total of four 521 Series pumps at Willenhall, with a further four dotted across its European operations. All of the units utilise an inverter to control speed, and all run continuously throughout the entire production period. Despite this demanding workload, Mr Jones says that maintenance tasks extend to no more than “spraying some lubricant on the rollers and springs every now and again.”

Easier cleaning

One final problem remained, however. The aggressive nature of some of the chemicals used within Prelok’s adhesive coating fluids meant that the Marprene and Tygon tubing deployed initially exhibited short working life, sometimes leading to ruptured tubes.

“Since switching to the Watson-Marlow peristaltic pumps this at least meant it was easier to clean and get the process up and running again; however, it was still an issue we needed to resolve,” says Mr Jones. “I contacted Watson-Marlow about alternative tube materials and our local sales engineer sent me a sample pack of different tubing material for me to immerse in our fluids to test for chemical compatibility. He followed up with a site visit and suggested we use a new type of pumphead (with quick-release couplings) and Gore Style 400 tubing to trial. So far we haven’t had a tubing rupture in the months it has been running.”

While chemicals will attack most other types of tubing, the secret behind the resilience of GORE Style 400 is Viton® GF-600S, a peroxide-cured fluoroelastomer based on DuPont advanced polymer architecture. Performance testing shows that Style 400 tubing offers greater than 50 times longer life than conventional non-reinforced extruded tube. Thanks to its expanded PTFE reinforcement, the new tubing also offers superior burst resistance to protect against the swelling effect produced when pumping aggressive chemicals using standard extruded tube.

For more information contact Watson-Marlow Pumps.