Since the invention of the magnetically-driven pump more than 50 years ago, most of its developments have been carried out on the magnets and the materials of construction.

The development of the magnetically-driven or hermetic pump has solved the problem of sealing hazardous chemicals without the use of rotating seals. The main problem associated with these pumps has been their inability to run dry without causing damage to the pump.

With this design, during periods of dry running, there would be heat build-up due to friction at the bearing surfaces in the pump. This results in pump failures after as little as 15 seconds of dry running, which can be a costly exercise taking into account repair costs and lost production.

To solve this problem, chemical pump manufacturer Argal has introduced the two-axial direction self-alignment system, reports West Rand-based pumps importer and supplier AquaPump MD Cliff Topper.

He reports that one of the firm's main products, Argal chemical pumps, boasts a range of pumps from small magnetically-driven pumps to 1 200 m3/h armoured pumps. It is with the magnetically driven pumps where the most significant development has taken place. Using innovative magnetic technology, Argal has eliminated both front and rear axial forces during periods of no flow.

It has introduced an additional magnetic field, which is always active and centralises the impeller assembly during periods of dry running, leaving only the radial friction of rotating. In constructing its range, the firm has designed its rotating parts to be as lightweight as possible, while maintaining the mechanical strength to operate at the maximum torque of the magnetic coupling.

2011-03-18

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