Fundamental rethink takes account of pharma needs

The needs of the pharma industry for greater sensitivity led Thermo Electron to undertake a fundamental rethink when developing its DSP Rx Pharmaceutical metal detector.

The key to achieving this is the company's patented QuadraCoil technology that uses a different coil arrangement to increase the radio frequency field. Rather than the conventional positioning of the transmitter coil inside the receiver coils, it is now placed on the outside to surround the receiver coils, thus increasing the flux in the area of the receiver coils. As there is now one transmitter coil for each receiver coil, a bigger field is created, resulting in a 15-20% improvement in spherical sensitivity.

The system was designed using new simulation software, which reduced the time to market significantly. It also revealed that the optimum frequency for achieving the best signal:background noise ratio was 700kHz.

Apart from its greater sensitivity, the DSP Rx incorporates a number of other features specifically aimed at the pharmaceutical sector. Adjustment of the head is supported by gas struts, enabling the height and angle to be changed safely and easily. All pneumatics and cables are positioned within the frame for improved hygiene, while the mounting bars are round to remove debris traps.

The AuditCheck continuous monitoring system has also been redesigned to be dust-tight. The tube is now sealed within the head to prevent the build-up of dust within the tube, while the compressed air is recycled, rather than being exhausted to atmosphere, to reduce the risk of operator exposure.

The design of the reject system offers a number of improvements with pharmaceuticals in mind. The mechanism is now operated remotely from within the cabinet for better hygiene. Rejected product passes down a chute, which is easily removed for cleaning, into an integral, lockable container that can similarly be easily removed.