Pneumatics technologies offer the clean designs and reliable operation required in food and beverage processing.
By: Josh Cosford, Contributing Editor
The food & beverage industry is unique in many ways, not the least of which is the obvious observation that it’s the only industry providing us with the nourishment for life. Unless you’re living off the land independently, you’re the benefactor of this multi-trillion-dollar industry that provides all the items in our pantries and fridges, ranging from produce to snack foods.
The other reason food & beverage is unique stems from the specific special requirements of the machinery and its environment. The industry is highly regulated, with various government agencies ensuring compliance depending on the operation’s location. Strict health and safety guidelines aim to reduce the likelihood of contamination, thereby preventing poor outcomes for consumers at large.
Contamination in manufactured and processed foods and beverages takes many forms, such as microbes, chemicals, physical objects, and allergens. Bacteria, viruses, fungi, and parasites may all potentially find themselves lurking within food and beverage products, each with the potential to cause illness and harm. Chemicals ranging from pesticides to heavy metals or from additives to cleaning agents could also find themselves accidentally infecting your food.
Nearly everyone has found an object in their commercially prepared food and drink, which ranges from metal or plastic pieces broken off from machinery or, heaven forbid, hair or band-aids. And, of course, we’ve all seen those package label disclaimers that advise you that your granola bar was made in a facility that also processes food containing peanuts and other tree nuts.
Materials matter
Luckily for the pneumatic component suppliers, we manufacture neither band-aids nor peanuts, but much of the air preparation, valve and actuator technology used to produce our beloved food and drink must adhere to strict guidelines while also offering reliability and value wrapped in a physically inert package. Pneumatics must provide the same rapid and compact lines of actuators used in other industries while leaving no trace of its own being in downstream food and beverages while discouraging the proliferation of nasty microbes harmful to humans.
Food and beverage components start their journey with appropriately food-grade materials, such as stainless steel, food-grade polymers and special coatings. 316L stainless steel is known for its ability to resist corrosion from acids, cleaning chemicals and the food ingredients themselves. Traditional steel will rust or corrode quickly, shedding contamination into the product while degrading to the point of premature failure.
The stainless construction of air cylinders and motors also ensures the chemicals and hot water (often under pressure) do not damage the actuators or result in rust formation. Between batches or production runs, machines and material handling systems are thoroughly washed down using various caustic, chlorinated or acidic chemicals to prevent microorganism proliferation or to remove residual chemicals for ingredients.
It’s possible that pneumatic food production components are made from aluminum or plastics, although the choice of materials must also be suitable for the production environment. Bare aluminum is not suitable and should be either anodized or treated with nickel plating to provide corrosion-resistant protection. When plastics and elastomers are used in food and beverage, such as with fittings, tubes, valves and seals, only FDA-compliant materials like PTFE (Teflon), EPDM, and silicone should be chosen, each of which is superior to other materials at resisting microbial growth while leaching little undesirable substance into the surrounding environment.
Seamless, clean designs reduce risks
The shape and design of pneumatic parts used in food and beverage should be thoughtfully designed to prevent effective cleaning to prevent the buildup of food ingredients or microbes. Cylinders made from extruded aluminum bodies with compound shapes, including grooves for reed switches, should be avoided for wet applications, as they are difficult to clean effectively. The same goes for die-cast heads and caps that use ribs, ridges or risers for strength, which for food and beverage just provide storage space for previous batches or dangerous bacteria.
Conversely, round body air cylinders with few grooves or crevices are an excellent choice for food and beverage, providing reliable actuators that are (relatively) inexpensive and easy to clean. If reed switches or position detection is required, sensors can be strapped to the barrel, where a magnetic piston strip can be sensed through the non-ferrous stainless tube.
However, when dealing with dry goods only, the shape of the cylinder is less important. The obvious products here are material handling actuators, such as hopper gate cylinders or Form-Fill-Seal machinery. But many dry goods applications are unique and require specialized equipment. A Dilute Phase Conveying system, for example, transfers dry goods by first metering the material with a rotary feeder driven by an air motor. The material is then introduced into a compressed air stream, where it sends the material to downstream bins, hoppers or mixers.
Other specialty pneumatic components are used in the storage and handling of food products or ingredients. Air shockers are one such animal and a type of cylinder used only to provide an impact force to dislodge or loosen stuck material. An air motor-driven vibrator is frequently used in hoppers and chutes to prevent material from sticking and may remain running throughout the material transfer process. These air vibrators are usually mounted to the outside of the hopper, so their construction material is much less important than those that may be within or near the food product.
Some industries, such as dairy, baby formula, nutritional supplements and meat and seafood, may take things a step further with “clean room” level pneumatics. A technique to prevent the introduction of any outside contaminants entering the product is to use vacuum actuators. Although less powerful than pressurized actuators because the best you can hope for is a single bar of pressure the atmosphere provides, a cylinder run by vacuum ensures air is always pulled through the system rather than pushed. Any leaks that may occur will not introduce contamination into the clean room, thereby guaranteeing a pure product despite leaks or failures.
Washdown resistance a must
As mentioned earlier, a consideration with the design of a food and beverage pneumatic component is that it will likely be subjected to a thorough washdown, which is often with hot water and sometimes at high pressure or with chemicals. If there are any electronics in, on or around the machinery, such as pressure switches, solenoid valves or sensors, they must also withstand frequent cleaning sessions.
Expect valves to also be washdown resistant, which means you must look for electrical components IP67 or IP69K rated. The Ingress Protection rating tells you how well the electrical device resists both solids (first number) and liquids (second number). IP67 describes a component that is impervious to solids and may be immersed in water for no less than 30 minutes. IP69K describes a component with the same resistance to solids while also withstanding close-range, high-temperature and high-pressure washdowns from various angles.
Automation on the rise
We can’t describe electronics in pneumatics without also addressing automation. With the proliferation of inexpensive PLCs, sensors and communication protocols, it’s never been easier to automate. Food and beverage is a highly competitive industry producing the same or similar products in many manufacturing plants, and as such, it is ripe for automation.
Although the automation of food and beverage requires no more from the control side not already mentioned, you’d be surprised at the level of sophistication applied to produce 100,000 loaves of bread or bottles of beer every day. Using decentralized control systems connected with one of the various industrial communication protocols such as PROFINET or DeviceNet, plant managers can keep an eye on every step of the process by viewing each substation in real time on one of the various monitors.
Modern pneumatics employ pressure sensors and switches, flow sensors, position sensors (both end-of-stroke and linear transducers) and vacuum switches, and most of these are used in high-volume food and beverage plants. Manufacturers now produce many of their smart sensors with wireless technology, ranging from Wi-Fi to Industrial 5G technology (and, of course, Bluetooth). Even older systems can be upgraded by adding wireless communication modules, providing a network of data that can be collected and trended with software.
The latest in material technology beginning to permeate the food and beverage industry is antimicrobial materials and surface treatments. Although traditional materials such as stainless steel and Teflon have always resisted the adhesion of particles and moisture, increasing the nickel, copper and chromium in either compounds or coatings has added inherent resistance to bacteria and other microorganisms.
One could argue that pneumatics for food and beverage is the most critical application using this form of motivation and power transfer. The world could get by without vehicles, semiconductors and material handling, but without pneumatics to process the vast amount of food and drink humans consume, our population would dwindle rapidly. It’s essential to recognize the unique requirements of this industry so that manufacturers can continue to design and build components that are both sanitary and efficient.
