Deceptively small
23/04/2013 ifm electronic ltd
Designed with wet areas in view, the new O6 WetLine photocells from sensor market leader ifm electronic may be small, but contain of lot of technology. ifm electronic pioneered the manufacture of truly food-grade sensor housings, and has followed this up with the O6 WetLine - a stainless steel sensor rated IP69K, addressing many needs of users with wet production areas.Best in class
The O6 series claims to possess best-in-class optical performance, for a number of reasons. One of the available variants, the O6H, a diffuse reflection sensor with background suppression, in other words designed to detect the direct reflection from an object without sensing what is behind it, has a sensing distance up to 200 mm, regardless of the colour of the target object. Even a black object (with 6% remission) doesn't pose a problem. In a wet environment sensors sometimes suffer with fine water droplets in the air (either just a misting or steam) causing unwanted reflection.
Not so the O6H. Compensation of the detection in the case of steam and mist is built-in, and a patent for this novel approach has been applied for.
Accurate sensing by the O6H is further aided by maintaining a tight beam (light spot diameter of 8 mm even at the 200 mm range.
Other problems encountered in a food environment stem from the reflections off stainless steel surfaces. ifm has countered this with optics capable of ignoring shiny
surfaces not simply behind a target, but also below the light beam path. When a stainless steel target surface is not precisely perpendicular, this can cause unwanted signals; again this has been eliminated with the O6H optical performance.
Optimised housing
ifm electronic paid particular attention to the housing; of which several aspects must be right for food production areas, notably the seal, the housing materials and the ability to keep the sensor clean. Testing in an autoclave and repeated dunking in boiling water then ice water have proven the resistance of the O6 to steam and temperature shock. All significant IP tests have been passed, i.e. IP65, for cold water jets from one direction, IP67, for 0.1 bar immersion for 30 minutes, IP68, for cold water immersion at 0.1 bar for seven days, and IP69K, for hot water jets (80 °C) at 80 to 100 bar from four directions over two minutes. It is also worth noting that the O6 range will happily operate up to 80 °C (from -25 °C), which is not the case with similar devices already on the market.
Compatibility, of the housing itself and the materials used, with cleaning chemicals has also been independently verified by leading manufacturers Ecolab and Johnson Diversey. Equally important in a food environment is the 'cleanability' of the housing, which was another focus point for the ifm design team. Even the potentiometer concept presents a cleanable surface.
Ease of use is important, and the ifm designers didn't overlook this aspect. Important details were considered, so for example, the LED indicators are rendered highly visible by being embedded in a dark background material for the highest contrast.
The full O6 WetLine range also includes standard (energetic) diffuse reflection types, with a range up to 500mm; retro-reflective (reflex) versions with 5m range; and through-beam (transmitter/receiver) with 10m range. All are available with either a 2m fixed cable, or a short cable fitted with an M12 connector. All O6 types can switch light-on or dark-on (equating to normally open or normally closed), and both PNP and NPN switching variants are on offer.
ifm always recognises that a sensor is not a stand-alone device: in needs to be installed and connected; to that end the O6 series is complemented by accessories equally optimised for wet areas. These include stainless-steel mounting brackets, the EVT range of mating M12 connectors, and also new chemically-resistant reflectors.
ifm is committed to working closely with its customers to develop products which precisely match their needs, and the company provides expert, readily accessible technical support to help users maximise the benefits they gain from ifm products.
For further information, contact Gemma Castle, ifm electronic Ltd., Efector House, Kingsway Business Park, Oldfield Road, Hampton, Middlesex, TW12 2HD. Telephone: 020 8213-0000. Fax: 020 8213-2228. E-mail - gemma.castle@ifm.com or visit our website www.ifm.com
Print this articleShare article:
Process and Control Today are not responsible for the content of submitted or externally produced articles and images. Click here to email us about any errors or omissions contained within this article.