The properties of PTFE as a food grade material that can be machined to close tolerances is often exploited in applications where any kind of chemical contamination needs to be avoided at all costs.
Recently, we were asked to develop a set of chevron v-seals made earlier with PTFE infused fabric, specifically to be used in the dairy industry. Our study into the existing seals being used by the client told us that the PTFE infused fabric was no longer the best option for what the client required. Fabric based components were first developed over thirty years ago and were a mainstay for many OEMs. Over time, as PTFE compounding techniques improved and the uniformity of the blend became consistent, these seals were replaced by either virgin PTFE seals or PTFE with fillers of glass, Ekonol (aromatic polyester), or even PEEK.
One of the primary reasons PTFE seals are used in the food industry is because of their resistance to chemical and biological contamination. PTFE is non-reactive to most chemicals and food ingredients, making it an ideal material for seals that come into contact with food products. Additionally, PTFE is naturally hydrophobic, which means that it repels water and other liquids, making it resistant to mould, bacteria, and other biological contaminants. This is especially important in the food industry, where contamination can lead to serious health risks for consumers.
Another important characteristic of PTFE seals is their durability and longevity. PTFE is a highly stable material that is resistant to most forms of physical and chemical degradation, including high temperatures, corrosive chemicals, and UV radiation. This makes PTFE seals ideal for use in food processing equipment that is subjected to harsh conditions, such as high-pressure washdowns, heat, or exposure to corrosive substances.
In addition to their resistance to contamination and durability, PTFE seals are also an ideal choice for the food industry because of their low friction coefficient. This means that they can easily slide against other materials without sticking or causing wear, which is important in applications where high-speed movement is required, such as in conveyor systems or packaging equipment. PTFE seals can also operate at a wide range of temperatures, from -200°C to 260°C, which makes them suitable for use in both cold storage and high-temperature cooking applications.
There are several applications in the food industry where PTFE seals are commonly used. One of the most common applications is in the sealing of rotary valves, which are used in the transfer of bulk materials such as powders, grains, and liquids. PTFE rotary seals are ideal for this application because they can withstand the abrasive and corrosive nature of these materials, while also maintaining their sealing properties over time.
PTFE seals are also used in other food processing equipment such as pumps, mixers, and blenders. These seals help to prevent the leakage of fluids or the ingress of contaminants into the equipment, which can compromise the quality and safety of the food products being processed. In addition, PTFE seals are often used in high-speed conveyor systems, where their low friction coefficient helps to minimize wear and ensure smooth movement of the food products. As a soft polymer, PTFE is unique in that it can take a tremendous amount of load (both mechanical and environmental), but that it will ultimately succumb to any major misalignment of mating metal parts. This means that in the event of failure, the seal will allow itself to be destroyed rather than damage the otherwise expensive equipment that it functions within.
The effectiveness of PTFE seals in ensuring the quality and safety of food products is unmatched. With their excellent performance characteristics and versatility, PTFE seals will continue to play an important role in the food industry for years to come.