Silicone makes excellent gaskets. It works over a wide temperature range, has a low compression set, high elongation, and is resistant to water, ozone, many acids, and UV light. If you’ve shopped for silicone gaskets or gasket material you probably noticed some formulations are specified as “food grade.” Here’s what that food-grade silicone gasket material means and why it might matter in your application.
Composition, Properties and Forms of Silicone Gasket Material
Silicone is an elastomeric polymer made from silica, (which is silicon dioxide, or sand), water and methanol. Silica is chemically inert and very stable, even at temperatures as high as 550 °F. It’s also an electrical insulator.
As a gasket material silicone has two weaknesses. First, it’s not oil-resistant and should not be used where it might be exposed to oil-based greases and lubricants. Second, it has poor wear and abrasion resistance so is best used as a static gasket rather than in applications where there’s sliding or dynamic contact.
Silicone gasket material is produced as a solid sheet in a range of thicknesses. It’s also available in foam and sponge form.
Food Grade and Non-Food Grade Silicone
Pure silicone is white. If it has no additives and is not ink-marked it will probably be suitable for use with foods. However, it’s important to check that it complies with 21CFR Part 177.2600 before using it in food or beverage-related applications. This is the FDA regulation that governs the purity of materials classed as food grade.
Some silicones are formulated with fillers, coloring, or both. This is to provide a particular appearance, improve wear behavior or reduce compression. However, some of these can leach out into the liquids or solids they come into contact with. If you need food-grade silicone gasket material with additives, check it meets FDA standards.
Ask Your Silicone Gasket Material Supplier
If you’re installing or replacing gaskets on food processing and preparation equipment they should be food grade, as defined by the FDA. Silicone is a good choice for food-grade gasket material. Contact Hennig Gasket & Seals for various silicone gasket material options for your application.