Starting from agriculture and food processing arriving at the packaging operation, automation is everywhere in the modern food plants and plays a fundamental role to address the required control movement quality, production speed, labour savings, and overall profitability. Especially for food zones and wash areas, where there are multiple national and international standards to take into account and frequent cleaning and sanitising cycles to support, pneumatics offers a cost-effective choice. Applications in food production typically require specific certification for air motors, pneumatic cylinders, and other associated equipment and special clean design features that minimize entrapment points for bacteria.
Environmental challenges
Food production environments necessitate frequent wash-downs of the work area, which can lead to damage to static and dynamic gaskets and seals. Constant exposure to damp and the caustic sprays of hydrogen peroxide and other cleaning materials used in wash-down cycles can eat away at unprotected materials. These environmental challenges have made stainless steel the most commonly used material for all food processing applications. Although stainless steel is more expensive than aluminum, it can resist the steam, high-pressure water, and caustic cleaners often used in food and beverage production. Parker P1VAS air motor and planetary reduction gear, for example, is built into a polished stainless housing that is sealed by a fluorocarbon rubber O-ring. The output shaft, which is made of polished stainless steel, is also sealed by a fluorocarbon rubber seal and thanks to the cylindrical shape, there are no pockets that can accumulate dirt or bacteria.
No matter which component is being specified, it’s critical to understand the details of the food processing application and what is required – such as pressure, temperature, flow, port sizes, configurations, and locations. Too often, filters or valves are chosen based on cost or size alone, forcing maintenance personnel to spend extra time on maintenance as a result of the system designer’s less than optimal choice. Longevity and repeatability are basic requirements for any good pneumatic solution. The choice should be made on products that have been thoroughly tested and designed to withstand the toughest conditions for operation, vibration, and impact.
Watch out for water
The accessories and options for pneumatic components are frequently neglected, so it’s important to ensure the entire product can withstand the environment where it will operate to avoid forcing maintenance personnel to waste time replacing parts. For example, the adjustment knob or T-handle of a typical regulator is made of a composite material. The caustic chemicals used in wash-down can corrode many types of plastic, so in addition to a stainless steel regulator, the knob should be made of stainless steel or other compatible material.
Filter-regulator options such as tapped manual drains or automatic stainless-steel drains are widely used to get rid of excess liquid and prevent water from draining onto the floor. Look for non-relieving regulators that do not release gases or liquid into the atmosphere. Whenever possible, select pre-lubricated or lubrication-free mechanisms that use food-grade grease and don’t require periodic lubrication.
Although some pneumatic valves meet NEMA protection standards or IEC/IP ratings, most are designed to be mounted in an enclosure to protect them during wash-downs. Check the design of this enclosure for any crevices between the valves and subplate or manifold bases and other non-smooth surfaces that can harbor bacteria. For those who use serial communications with their valves, these electronics also require protection.
Components that require lubricated compressed air or periodic manual lubrication should be avoided when working in food processing to minimize the risk of product contamination. The lubricant in the compressed air can collect near exhaust ports, and manually applied lubricant can spill onto or collect on multiple components.
Using dry air in non-lubricated applications is critical; condensation can corrode system components, increasing maintenance costs and reducing system efficiency. Also, unless distribution airlines are made of stainless steel, aluminum, or high-strength plastic, water can create pipe scale that can work its way into components and cause malfunctions. Water is a poor lubricant; when emulsified with residual compressor oils, it becomes a milky substance that must be drained away. In addition, there should never be any contact with synthetic emulsions in food processing. Dry, filtered, non-lubricated air usually eliminates these issues.