Designing out contamination
Contamination can impact almost any kind of industrial process. Contamination can mean stopped production, followed by costly cleanup, loss of reputation and unhappy customers.
The highest profile risk is to the food and beverage industry. Over the years there have sadly been plenty of examples of contaminated foodstuffs being released into the consumer market. However, the same considerations extend beyond the food and beverage industry. Pharmaceutical manufacturing, chemical, mining and in fact any complex manufacturing process is vulnerable to the risk of contamination of one sort or another.
It is easy to think of contamination control as an emergency clean-up operation, and there is a range of products, techniques and technologies that will help. However, once this has happened the damage may already have occurred. The factory may be halted, the production batch may be ruined, and customers may be disappointed.
Contamination control should not be an afterthought. Equipment can be designed with the express intention of removing as many sources of contamination as possible. By designing with these requirements in mind, your equipment can help prevent the very contamination that puts your processes at risk:
- Ease of cleaning
- Prevention of ingress and leaks
- Easy detection of contamination
- Simple clean-up procedures
One of the simplest ways to prevent contamination of any manufacturing process is to keep the factory environment clean. Most equipment destined to be used in such environments will be designed specifically to be washable, but attention to detail can make this easier. The correct selection of materials and components will ensure your facility is ready.
Stainless steel has long been used in food and beverage applications, and with good reason. Stable, strong and easy to wash, the current range of stainless steel enclosures are sealed to IP66 to make cleaning easier. A perfect example would be the AE series from Rittal (784-6121), a range of 304 stainless steel wall boxes that are perfect to protect your delicate electronics.
Fig 1. Rittal AE Series Enclosures
The apertures which allow cables into and out of your enclosure also require careful consideration. The usual method is to use a gland which allows the cable to pass through the wall of an enclosure whilst keeping the enclosure itself sealed. German manufacturer Lapp has recently introduced their latest SKINTOP cable glands for exactly this application. The gland itself (796-0044) is manufactured in stainless steel and is designed with a smooth profile to minimize the accumulation of moisture, dust, contamination or food residue. The rubber seals that provide a high degree of environmental protection are silicon and are supplied in the blue colour that is used frequently in food and beverage applications. Should any part of the seal break off due to improper use, the blue colour makes for easy identification.
Similar consideration should be applied to the cables themselves. It is vitally important that any cable used should be able to withstand the environment, both mechanically and chemically, and also that it should not itself be a possible source of contamination. LAPP Olflex cables (800-3280) are designed specifically for the food industry. Physically strong and flexible, the materials used in their construction have been chosen for their resistance to steam and chemical cleaning.
In some applications, the use of a fixed cable inlet such as a gland is impractical, and a connector needs to be used. Many of the same design features of the cable gland can be found in connectors too. An example would be the F&B series of connectors from leading manufacturer HARTING. Manufactured in this case, not from stainless steel, but from food-grade polypropylene, the connector provides IP69K sealing, making it ideal in situations where the machinery is cleaned using high-pressure sprays. The F&B connectors are designed to be used with the inserts from the market-leading Han connector series, making is incredibly versatile.
Fig 2: HARTING F&B Connector Series
In instances that require operators to control process equipment, a whole range of switches are available in a wide array of technologies. From membrane switches made with anti-microbial coatings to sealed keypads made in stainless steel, the right solution is out there. Switch manufacturer APEM has a range of stainless steel piezo switches (691-9575). Piezo switches work without the need for moving parts, which allows a switch based on piezo technology to be completely sealed, and are therefore ideal for contamination-sensitive environments.
Fig 3: APEM Piezo Switches
Despite the best efforts of the designer and operator of equipment such as this, failures do sometimes occur. However, by thinking about such failures might occur, it is possible to design equipment in such a way to keep disruption to a minimum. Plastic or rubber components can sometimes fail under constant use and can be very difficult to detect if they have broken. In food production environments, X-ray inspection is sometimes used to ensure that no metal parts have mixed with the food. It is possible to select plastic products that are designed with metal content, making them visible to X-ray inspection. For example, HellermannTyton manufacture the MCTS series of cable ties (832-6993) which include metal content, making them magnetic. Other solutions include choosing products made from plastics that float, making identification and removal simple.
Contamination control doesn't have to mean cleanup. As we have seen, clever design can build contamination control into the heart of every system. Whether it's choosing the right material or using the latest techniques, there are plenty of ways to keep your manufacturing environment safe.