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KEEPING COMPUTING SYSTEMS IN
FOOD PLANTS CLEAN Computers in food plants have to be cleanable so they don’t add any contamination load to the end products. So they must be able to withstand the cleaning and sanitation regimes of the plant.
T
he food industry relies heavily on computer-based control systems and human-machine interfaces (HMIs) to automate and control manufacturing and other processes and also to communicate with human operators. These computers are frequently out in the plant itself and so must be able to withstand the plant environment and be able to be kept clean so they do not contribute any contamination potential to the foods or beverages. This means that the equipment will be periodically subjected to high-pressure washdown and exposed to cleaning and sanitising solutions to protect against biological contamination of the end product.
Sealed computer or sealed enclosure? The deployment of computer equipment in such washdown environments presents a particular set of options and trade-offs to the system designer. One key issue is whether to specify a sealed, industrially hardened computer that’s ready to deploy in a washdown environment or to specify an appropriately sealed industrial enclosure into which a more general-purpose computer can be placed. Either approach can perform admirably when it comes to the basics of routine operation: meeting the process’s sanitation requirements while protecting electronic equipment from water sprays and temperature extremes. Over the long term, however, the choice between the two is an investment decision that must balance life-cycle costs, operational continuity and the accelerating pace of information technology.
32 WHAT'S NEW IN PROCESS TECHNOLOGY - MAY 2015
Equipment protection in industrial environments The IP (International Protection Code and Ingress Protection Code) rating for equipment or enclosures gives a quantifiable measure of protection against intrusion by either solids or liquids. The IP Code, specified in Australian Standard AS60529 and also EN60529 and IEC 60529, consists of two numbers and an optional letter, such as IP67. The larger each digit, the greater the protection. The first digit represents the level of protection against solid objects. It ranges from 0, which means no protection, through protection against large objects such as hands (1) to total protection against dust ingress (6). The second digit in the code represents protection against liquid ingress. Once again, 0 implies no protection. Numbers 1 to 6 give increasing protection from falling drops of water through sprays up to high-pressure water jets. A rating of 6 will cover you for ratings 1 to 5 for both solid and liquid protection. Liquid protection ratings of 7 and 8, however, are separate. These digits give a measure of protection against immersion but do not imply spray protection as well. There may be additional letters after the two digits. These letters can be appended to classify the level of protection against access to hazardous parts by humans. For example: A - back of the hand, B - finger etc.
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