Lubricating the way to higher standards

The food industry differs substantially from other industries in its demands for lubricants, with the emphasis not simply being on technical performance. A great deal of attention is also given to issues such as cleanliness, health, safety and preventing contamination.

All food producers are naturally keen to avoid any contamination incidents which can lead to product recalls, adverse press headlines and extremely costly court cases initiated by lawyers seeking compensation for victims. The correct choice of lubricant can make a significant contribution to ensuring harmful contamination is avoided during the manufacturing process.

There are ongoing calls from the food industry and raw material suppliers for lubricant manufacturers to develop and recommend special lubricants for use in processing foodstuffs. More demanding legislation and higher hygiene standards, such as the HACCP concept (Hazard Analysis and Critical Control Points) are making it increasingly possible to clearly identify lubrication points where there is a possibility of foodstuffs becoming contaminated.

Manufacturers must ensure the lubricants continue to fulfil their primary functions, including lubricating machinery and components, heat dissipation, wear protection, friction reduction and corrosion protection. Components such as line lubricators, slide and roller bearings, chains, compressors, vacuum pumps, gearing, heat transfer systems, hydraulics and pumps are commonplace in food production plants. Many of these are found in close proximity to the foodstuffs, often with a high potential for any leaking lubricants to make direct food contact. For example, high pressure hydraulic hoses run alongside production lines, with motors and gearboxes frequently located above the lines.

The plant and equipment itself does not differ significantly from that used in other industries, but the environment in which it operates presents a number of unique and complex challenges. The necessary daily washing of machinery with aggressive cleaning products under high pressure increases the chance of lubricant contamination, and highly reactive substances such as fruit juice can degrade oils and greases. The industrial processes often operate at extremes of temperature, ranging from freezer systems to high temperature ovens.

Lubricant manufacturers supplying the food industry must possess specialist knowledge, based on extensive research and development, together with practical experience, to ensure the most effective lubrication products and management regimes are implemented. Close working relationships between the lubricant manufacturer and the foodstuffs manufacturer, ensure the best possible lubricant is specified and developed. An ongoing partnership allows technical experts to monitor and analyse the lubricants in action and use the results to specify optimum maintenance intervals. Oil change intervals depend more on contamination of the lubricant than on the reduction of its lubrication properties through the degradation of additives, or oxidisation of the lubricant.

In the event of a contamination issue, regional legislation states that a food manufacturer is liable unless able to demonstrate that every conceivable step has been taken to prevent the contamination. Regulations governing food hygiene came into force in December 1995 and are incorporated in the Food Hygiene Regulations of the Consumer Goods Act. The HACCP concept is a major aspect of these regulations. Another important piece of legislation governing the food industry is the European Hygienic Equipment Design Group regulation, providing guidance on the Design of Machinery for Food Processing Purposes.

However, there is no European standard for food-compatible lubricants. It is therefore normal practice to rely on the US standards issued by the Federal Food and Drug Administration (FDA) and the US Department of Agriculture (USDA). When the USDA ceased registration of lubricants in 1998, the function was taken over by NSF International, a not-for-profit independent organisation, previously known as the National Sanitation Foundation. Certification with NSF allows the use of the highly recognised and credible NSF certification mark on products.

As already highlighted, the specification for food industry lubricants is not governed exclusively by technical considerations. Manufacturing processes and equipment are designed and developed with hygiene as a key consideration. The lubricants need to be designed in as part of the overall specification, and the constraints in specifying lubrication systems are likely to be more restrictive than in other industrial sectors. Until recent years, the formulation chemist was severely restricted by the limited number of permitted additives and base oils, and as a result it might not always have been possible to achieve high levels of lubricant performance.

Machinery and component manufacturers are also setting their own standards, based on the widely accepted US guidelines, regulating additives and base oils in the formulation of food-compatible lubricants to be used in their equipment. Throughout the industry in general, the majority of original equipment manufacturers (OEMs) now recommend lubricants which meet international standards such as ISO, DIN, IP and ASTM. Obviously these standards also need to be attained in lubricants designed specifically for the food industry, and this can only be achieved by equipment and lubricant manufacturers working closely together.

OEMs can be divided into manufacturers of production equipment, and manufacturers of components. Manufacturers of production equipment and machinery usually provide their customers with a list of suitable lubricants. The lubricants recommended are usually those which have already been proven safe for use in the food industry. Such recommendations are often based on experience gained in the field by machinery and lubricant manufacturers. Manufacturers of components, such as hydraulic pumps, transmissions, bearings and seals tend to recommend lubricants which meet the international standards and have also passed further in-house tests. However, these tests and the standards applied to the lubricants by component manufacturers can fail to take into account the special requirements of the food sector. They do not always verify whether substances are certified as food-compatible, nor do they take account of the unique manufacturing environment within the food industry.

Ongoing monitoring of lubricant condition is important in any industry, but it has particular significance in the food sector. It is important to remember that the analyses and information regarding the toxicity of lubricants and the additives they contain relate to new lubricants before they have been used. As it is used, a food-compatible lubricant is exposed to a number of influences such as oxidation, heat, humidity and a decline in its lubricating properties. This can affect the toxicity of the lubricant and consequently it should be regularly checked.

In addition, it is possible that lubricant can become contaminated by external influences such as water, dust and cleaning products. This may cause potentially harmful reactions, therefore ongoing monitoring is essential to ensure that the condition of the lubricants remains effective and that they do not come into contact with food stuffs.

Not only do these reaction products pose potential contamination hazards, but they can also have a damaging effect on the production plant. The useful life of the oil is reduced and premature wear must be avoided through more frequent oil changes. The level of lubricant degradation can only be accurately assessed by taking and analysing oil samples. Regular analysis of samples from transmissions, compressors and hydraulic power units reveal the wear patterns in key machinery components and allows an examination of the chemical and physical condition of the lubricant, including any impurities and contamination. It is important that personnel responsible for administering lubrication management systems are trained, and customers are usually keen for lubricant suppliers to organise seminars for their plant operating teams.

Although the same production facilities can be used for food-compatible lubricants as the standard products, more stringent rules are applied in order to achieve the highest purity levels and avoid the possibility of cross contamination. Production facilities such as conduits, mixing vessels and bottling plant must be certified to ISO 9001/14001 for the manufacture of food-compatible lubricants. A number of high quality lubricant manufacturers have even carried out their own critical control points (CCP) analysis, and use food-compatible lubricants in their own manufacturing plant.

The National Lubricating Grease Institute (NLGI), the European Lubricating Grease Institute (ELGI), the European Hygienic Engineering and Design Group (EHEDG), and NSF have coordinated a project to enable lubricant manufacturers to undergo independently audited HACCP exercises. Participating manufacturers would become officially registered within the system. A further objective of this project is to allow an independent body to take and analyse lubricant samples directly from the market.

Food manufacturers, OEMs and lubricant producers continue to work towards improving the performance of food-compatible lubricants. Although there has tended to be a degree of geographical variation, the historic opinion was that lubricants for the food industry did not match the performance levels of standard lubricants. There have been significant developments over recent years, with the leading lubricant manufacturers working with OEMs and the food industry to dramatically improve performance and choice.

Synthetic base oils (polyalphaolefins) are being increasingly used, and considerable progress has been made in refining white oils – practically the only base oils used in food applications until recent years. Additive technology has also progressed significantly giving formulation chemists much greater scope to improve performance whilst working within the stringent guidelines governing food-compatible lubricants.

As a result, modern lubricants for the food industry such as the Shell Cassida range now achieve performance profiles at least as high as those of conventional synthetic lubricants. Today’s superior lubrication products, combined with carefully planned and implemented lubrication maintenance schedules, offer food manufacturers the ultimate peace of mind of knowing they have minimised the risk of product contamination.