Pneumatics are commonly used in the food industry for processes that require mechanical power, such as pack ing, compacting, trimming and processing, as well as conveying, aerating and drying.
The advantages of pneumatic systems include reliability, low maintenance requirements and low cost. Pneumatic power is harnessed by the use of pneumatic actuators, which convert the potential energy of compressed gas into kinetic energy (movement).
In the food industry, the compressed gas is usually compressed air, and this is able to expand without any input of external energy. In a simple actuator, this expansion forces a piston to move, and a piston rod transfers force into the object to be moved. The motion produced can be rotary or linear, depending on the type of actuator. Types of pneumatic actuators include cylinders, grippers, rotary actuators, rod-less actuators and vacuum generators.
While pneumatic systems are commonly used in many industries, food processing facilities have some unique requirements. For example, the quality of the compressed air is an important consideration. Air quality affects the performance and life of pneumatic components. In addition, and perhaps more importantly, food safety can be affected by compressed air quality, and this can be overlooked by quality assurance and food safety teams.
Food safety is at risk when compressed air is used for appli cations, such as aerating ice cream, manufacturing beverage containers, and drying the inside of bottles and jars prior to filling. Where there is incidental or direct contact between food and compressed air, the air can be a source of microbial contamina tion, dust contamination and con tamination from toxic and car cinogenic compressor oil. speci fied by most food plants, compli ance is extremely low, due to the lack of availability, high cost and poor performance of food grade compressor oils. Reconfiguring a compressed air system to provide food-safe air can be as simple as installing dryers and filters or as complex as replacing air lines with corrosion-resistant piping and purchasing ‘oil-free’ com pressors.
Valves, actuators, fittings, filters and pressure sensors also have an impact on food safety. The most important attribute of pneumatic components, with respect to food safety, is the “cleanability” of their external surfaces. The requirement for cleanability depends on the area in which a pneumatic component is to be used. Any food processing system, such as a conveying system, can be divided into zones. The food zone is the area of the system in which a device could come into contact with food in the product stream. The splash zone includes areas where a device could come into contact with spilled or splashed food. The non-food zone is the area of the system in which a device will not come into direct contact with food.
There are different requirements for components, depending on the zone they will be situated in. Wash-down is a consideration, and corrosive products are commonly used in the food industry, both in the form of food products and wash-down chemicals. High temperatures, vibration and impact resistance are also common requirements for food industry applications.
For food zone components, the external parts of the cylinder, valve or other component should be smooth, cavity-free and made of non-porous, corrosive-resistant materials. They should also be lubrication-free or pre-lubed with food grade lubricant. Stainless steel of AISA grades 304 or 316 is recommended. Anodized aluminium and food grade polymers such as polycarbonate and poly amide are also acceptable. Carbon steel, zinc, chrome or brass alloys not only provide less corrosion resistance, but are not considered suitable for direct food contact. In addition, components made of these materials are sometimes coated with polymer coatings that can contaminate food.
Components which will be situated in the splash zone and non-food zone have less stringent requirements for materials and design, but they still need to be easy to clean, or they may become a harborage for dirt and bacteria. When considering control boxes and the like, IP ratings provide a good indication as to how they may be cleaned.
Pneumatic equipment has an impact on food safety during food manufacturing, and this can be overlooked when purchasing, upgrading or maintaining plant. Compressors, air treatment equipment, piping, valves, cylinders and other components will be chosen on quality, performance and cost. Make sure you include food safety considerations in the list.
HACCP Australia
02 9956 6911
www.haccp.com.au