A recipe for success
Steve O'Reilly, Market Development Manager for the Pneumatics Division of Parker Hannifin, looks at how pneumatics have to work in tough conditions in the food manufacturing sector.
Machinery used in the food and beverage processing and packaging sectors has to operate under some of the toughest conditions found in industry. Equipment has to be efficient, reliable and easy to maintain, while being suitable for extensive cleaning and in some cases high pressure washdown. It also has to comply with a range of environmental, safety and hygiene legislation, including: the European Machinery Directive, the European Hygiene Directive, ISO 14159:2002 Safety of Machinery, DIN 11483 for the Dairy sector and EN1672-2:2005 covering hygiene requirements for food processing machinery.
EN1672 is perhaps the most encompassing and sets out to define three areas for hygiene requirements: Food Area, covering surfaces in contact with food where there is the risk that contamination can be transferred back to the process; Splash Area, covering surfaces with which the food product can come into contact, but where there is no risk of contamination returning to the process; and Non-Food Area, which essentially covers all surfaces not included in the preceding categories.
EN1672 has some interesting implications for companies manufacturing equipment for the food sector, as it effectively controls the materials of construction and the design and configuration of process components. For example, products used in Food Areas must have surfaces that are self-draining, sealed and smooth, and must be corrosion resistant, non-toxic and non-absorbent, with radiused edges to eliminate all risk of potential contaminants becoming trapped. Even in Non-Food Areas, exposed surfaces must be corrosion resistant and be easy both to clean and disinfect.
In practice, this means that stainless steel is widely used in Food Areas, along with plastic materials manufactured from PVC, polythene, PTFE or silicone rubber. In less demanding areas, chrome or nickel plated steel, or nickel plated anodised aluminium is used, along with Polyamide, Nitrile rubber and NBR, while in Non-Food Areas zinc plated steel, bronze, zinc and polycarbonate are common.
It's also worth noting that food processing and production facilities are generally designed around the internationally recognised HACCP (Hazard Analysis Critical Control Point) system for food safety management. This defines seven key principles that should be followed, from initial hazard analysis, through the determination of critical control points, to identification of control procedures, monitoring and record keeping.
As pneumatics is the most widely used technology for controlling the many different process, handling and positioning operations in food production and packaging it is important that pneumatic systems both conform to standards such as EN1672 and comply with HACCP principles.
Meeting international standards
To make life as simple as possible for OEMs and line operators alike, many of the latest pneumatic cylinders, air motors, valves, filtration equipment and fittings have been developed with the requirements of these standards in mind, making them easy to specify, install, use and maintain. For example, although stainless steel cylinders have been available for some time, they have become progressively more robust and reliable to meet the needs of more demanding applications, such as those of meat, poultry and fish processing. Parker's ISO standard stainless steel cylinders feature scraper rings, piston rod bearings and seals with self lubricating characteristics suitable for dry operation, plus pneumatic end cushioning exact setting, allowing heavier loads and higher speeds to be accommodated. Additionally, all moving parts are pre-lubricated with food industry approved grease according to USDA-H1 standards.
Both stainless steel and conventional aluminium bodied cylinders are now available with smooth, clean-line surfaces. This is achieved by improving actuator body designs and end caps, enabling them to be self-draining and prevent the ingress of contamination, even when subjected to regular washdown.
The latest stainless steel fittings, such as those from Parker Legris, also follow this clean-line design. Surfaces are highly polished, free from dead zones and protrusions, with smooth faces to ensure that cleaning fluids can flow effectively over each unit. Seals are manufactured from FKM, which is a tough fluoro-elastomer capable of resisting high temperatures and aggressive chemicals and ingredients, and are integrated with the body, collet and sub-base into a single component. Similarly, the latest air motors incorporate air motor and planetary reduction gear into a single, integrated and compact stainless steel housing, protected by long life fluoro-rubber O-rings and seals. In addition, the cylindrical housing is virtually smooth, being free from potential traps that might otherwise harbour bacteria, while the vanes within the air motor are designed to operate reliably without the need for lubrication, thereby eliminating the potential for atomised oil to be transferred to exhaust air.
It is worth noting that the use of compressed air can in itself be a potential cause of contamination, as the thinly scattered air-borne particles, pollen and water aerosols that occur in the atmosphere will become increasingly concentrated as they are drawn through the compressor. As a result, concentrated contaminants can be passed through the compressed air system and be ejected in exhaust air from cylinders, air motors and other devices. Although there is currently no legislation covering the quality of compressed air used in the food sector there is an established Code of Practice, issued by the BCAS, that defines compressed air as Contact, Non Contact, or Non Contact High Risk. Each category has defined limits for the maximum number of particles and water aerosols contained per cubic metre. It is therefore sensible to ensure that HACCP protocols cover both the compressor and associated filtration, either at the compressor end or downstream of it using high efficiency water separators, coalescing or adsorption filters, and adsorption or refrigeration dryers.
With the food sector being one of our few recession-proof industries, and with a growing number of dedicated reliable components being available, plus clearly defined guiding legislation, it is now far simpler for OEMs and end users to improve both the productivity and profitability of process and production systems, while ensuring that product quality remains at an all time high.
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