Out with the old, in with the new

Biopharma, the European distributor of Asepco, is marketing a new design of magnetic mixer that the company claims will eliminate many of the problems seen with traditional top and bottom mount mixing vessels.

Disadvantages of top mount designs include: the need for high head clearance; a tendency to be top heavy; an inability to mix to the bottom of the vessel; and extra maintenance and difficult motor and drive access resulting from the need for double mechanical seals. Bottom mount magnetic drive mixers, meanwhile, can suffer from warping and impeller fit problems caused by the large welding diameter on the mounting plate; decoupling problems due to the wide design; limited mixing modes; and restriction of the blade to the bottom area of the tank.

The Asepco PolyMixer claims to be a new generation of mixing system providing a better mixing performance in CIP and SIP process systems, thanks to the design and assembly of the motor.

There is a wide choice of agitation blade designs, which ensures optimum process flexibility and allows users to customise their mixing dynamics. Extended multi-blade shafts are available for agitation of the total tank volume, enabling mixing region specialisation.

Asepco is able to offer a true indication of the mixing speed based on impeller rpms rather than the potentially misleading measurement of motor speed. 'The development of internally mounted mag-drive aseptic mixers with 'true' tachometer readings from the impeller, is a great improvement,' said Katherine King, sales executive for Biopharma. 'Previously you could never know for sure how fast the impellers were turning, and you could be completely unaware of any decoupling problems within your vessel.'

King continued: 'The next challenge is likely to be in the development of a new material for making the bearings for magnetic mixers. This would ideally be a stronger, more durable material that allows larger loads to be mixed and faster revolutions of the impeller. This has to be achieved without introducing heat into the vessel and without introducing any contaminating particles. Asepco currently uses tungsten carbide to make the bearings for the new PolyMixer, but as new developments in material science emerge, new materials should become available.'

The PolyMixer is available in 316L stainless steel, Hastelloy, C-22, C-276 and AL6XN. Impeller speeds are from 0-1,800 rpm and motor types offered are DC, AC or air. Tank volumes range from 5 to more than 20,000 litres.