There’s a number of factors to take into consideration when designing seals for the food industry. That’s because seals used within this sector need to work exceptionally hard in all food processing environments where hygiene and health and safety are of the utmost importance.
When designing, or indeed looking at the design of a seal for food applications, you must take into consideration:
Operating conditions
For example, what application is the seal intended for? Does it experience any movement? What is the makeup of the piece of equipment being sealed, etc.?
You also need to consider the temperatures, speed, and pressure that the application will be operated at. As well as the maximum and minimum pressure levels, temperature, and speed.
Knowing how the application will be operated will ensure that the correct seal is chosen and used.
The fit of the seal
Knowing how the application is to be assembled allows you to understand exactly where the seal will fit and its role within the appliance. Addressing any fitment issues from the start can save you time, money, and a lot of headaches in the long run.
Where the seal will be housed
Knowing where the seal will be housed is vital.
For example, aluminium housing will require a different choice of material compared to that of stainless housing.
Seals manufactured using PTFE materials need to be passivated when used with stainless steel, preventing stainless surfaces from pitting.
Cleaning methods
Within the food industry, cleaning is critical. A sterile environment is a must, and as such harsh and stringent cleaning methods will be used. Because of this, some seal materials may be eliminated, leading to replacements being required or seal gaskets in need of vital repair.
Testing seals against cleaning solvents and methods need to be conducted in order to test the seal’s overall performance and robustness.
Movement
Movement plays a big factor in seal design. For example, long or short strokes or even strokes and frequent strokes can lead to the seal becoming starved of lubrication, which will result in excessive wear and tear on the seal. This is known as a linear movement (back and forward).
Alternatively, the mixed movement will require the seal to handle challenges linked to temperature fluctuations, extreme heat, as well as being able to function during the transition from one motion to another.
If a rotating motion is in play, then the seal required needs to be able to create low friction, due to the issue of a build-up of heat in these applications. From a design perspective, heat dissipation away from the seal contact area should always be incorporated in order to reduce the heat gradient.
Static movement is found in many food applications, and this requires no voids to be present in order to avoid bacteria from growing and spreading. For these types of applications, specialist seals need to be designed to bulge, reducing the need for welding joints.
Stationary stability needs to be considered as it is known that many foodstuffs can solidify if they remain stationary for a period of time. For example, solids like sugar can have a negative effect on many seal materials, and seal designs must bear this in mind.
Seals must be compliant
Food hygiene and quality are of high importance, and seals should be FDA approved and compliant at all times. If providing applications outside of the UK, you also need to consider the European Commission food regulations and Good Working Practices.
Ultimately seals that are designed for the food industry should demonstrate a broad chemical compatibility profile, be resistant to high temperatures and abrasions, and have the ability to withstand aggressive cleaning methods.
To ensure the seals that you are using are designed to be FDA compliant, safe, and effective, speak to Specialist Sealing Products today.
The sealing experts in Leeds.
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