Level switches to provide reliable performance
12 December 2008
Premier foods manufacture a range of ready meals and soups including the popular Batchelor’s, Pasta’n’sauce, OXO and Vesta brands at their site in Ashford, Kent. They use many level probes to this site, needed to deliver reliable performance on applications like controlling the level of feed hoppers supplying packing machines filling sachets and containers.
The view inside the hopper before the switch was fitted showing the agitator
These machines run at speeds varying from 160 - 600 per minute, feed hoppers vary in size with various agitators and vibrators assisting with the flow of the powders.
One machine in particular packages a very familiar product to us all, ‘Batchelors-cup-a soup’ variety sachets. The machine packs at a rate of 160 sachets a minute handling differing flavours and consistencies of powders, some are drier, or with larger particles, others more adhesive, as some of the ingredients contain minute amounts of natural oils. To ensure even flow and mixing, the hoppers incorporate a small rotating agitator, to ensure consistent product flow and mix as the sachets are filled. Previous switches had reliability problems, particularly when products were changed over.
Vibrating fork devices have been supplied with remote electronics housings and quick release, hygienic fittings to enable fast removal and clean down between product changes. The units have proved reliable with all different products running through the machine with a design robust enough to work reliably even next to the agitators inside the small hopper. Because it mounts from any orientation, it also has an advantage over proximity-based detectors, which need a polymer window into the vessel. There is a concern over this type of window, should it crack or chip, the minute plastic shards can be almost impossible to detect.
Vega have supplied their Vegawave level switches on this small yet challenging application. Vibrating level switches combine mechanical detection – using the damping of a vibrating element – with reliability of electronic solid-state electronics. Self-checking is built in, electronic monitoring of the vibration frequency means that any damage, very high build-up or device failure makes the switch an inherently safe device. Vibrating technology is also easy to set up compared to capacitive techniques and more reliable when compared to rotating paddle devices.
Vegawave fork and Vegavib rod vibrating switch devices with adaptive digital technology for solids combine performance with fast delivery and a wide range of options to suit any budget. Devices are available with ATEX and SIL conformance.
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