Given the wide range of chemical compounds and synthetically produced substances local to food and beverage production establishments, machinery’s engineered components must meet stringent requirements regarding purity. Leading standards agency, the U.S. Food and Drug Administrations (FDA), as well as regulations laid out by the European Commission prohibit the use of non-compliant food-contact materials (FCMs). These, and other similar jurisdictions of course apply for sealing material, which is one reason why careful deliberation is vital when seeking out a solution.
Why materials matter
Failure to adhere to such standards is punishable in an industry which has a moral obligation to safeguard its workers and eventual consumers of products. What’s more, brand integrity is always at stake in a competitive market, and tarnished reputation can be hard to shake off.
It’s also important to remember that this is an industry which represents some of the most demanding operating conditions for both rotating and reciprocating equipment. Depending on the task at hand; be that cooking, chopping, pasteurizing, or packaging, seals must contend with pressure, force, and temperature extremes on a daily basis, which can compromise a seal unless the material is right for the job. The seal’s application conditions (i.e., rotary or reciprocating motion, pressure level, and involved foodstuffs) can especially influence the decision regarding a suitable material. To add to these challenges, chemicals used for cleaning and sterilization can also impact seal lifetime and reliability. The risk of costly stoppages, maintenance, or product recalls is just too high not to take material selection seriously.
Food for thought
Food-contact approved seal materials offered by SKF include premium-grade polyurethanes with excellent hydrolysis resistance for TPUs, various elastomers, (FKM, EPDM, MVQ, and HNBR) polytetrafluoroethylene (PTFE) grades, and other thermoplastics needed for sealing assemblies. This range helps OEMs and end-users meet their sealing requirements and remain on the right side of the law. Which one will be used, however, depends entirely on the application. Selection necessitates a complete understanding of operating limitations and how substances effect certain compounds. Special sanitary requirements aside, seals need to be resistant against the food involved, certain chemical substances used in cleaning cycles and other process media. For example, EPDM rubbers show excellent resistance to heat, hot water, steam and many cleaning agents, and polar organic solvents. That said, EPDM is incompatible with vegetable oils and fatty media, in which it shows extremely high-volume increase.
Hydrogenated nitrile rubber (HNBR) can provide a surefire solution where fatty substances are concerned. The copolymer elastomer is resistant to animal and vegetable oils and fats, as well as hot water. It is unsuitable for contact with concentrated acids such as nitric and formic acids, and oxidizing media like peracetic acid.
On top of compatibility with materials such as lubrication, cleaning products, or process media and foodstuffs, seals should be able to withstand (either high or low) temperatures depending on the intended application. Another key attribute is the hardness of the sealing material, which should always match application pressure loads and seal design.
With so much to consider regarding material selection, SKF’s network of seal product engineers are always on hand to assist any decision making. Also, our food and beverage seals catalogue can help you to find the right materials based on your requirements and industry regulations.
Download your version and refer to page 6-7 for the guide.
Know your rights!
As already touched upon, sealing material composition must comply with different standards depending on where the seal is manufactured and where it will be used. That said, rules that define a compliant sealing material differ. In the USA, the FDA lays down requirements on food contact materials for different material classes, such as allowed ingredients and quantities.
A second set of standards applies in the USA. The 3-A Sanitary Standards relate to rubber materials which come into contact with dairy and food equipment within production facilities.
In Europe, the EC1935/2004 framework comprises general requirements for food safety, including the use of FCMs, EC2023/2006 outlines “good manufacturing practices”, and regulations such as EC10/2011 for thermoplastic materials offer material specific requirements.
Don’t go it alone
With so much to think about regarding seal material selection, it can be wise to draw upon experts like SKF who can assist in planning from the very beginning. Sealing engineers can develop optimized solutions for a range of industries and processes with the customer by their side throughout. This includes assistance regarding standards conformance, defining operating limitations of equipment to find an appropriate solution for the task.
To gain an understand of just how food and beverage companies can benefit from well planned and properly thought-out sealing solutions, SKF offers several case studies like this one about an upgraded solution for a dairy homogenizer are available at skf.com!