What are the different materials for gaskets?

There are several popular elastomers and plastics used in food and beverage facilities, but which one is right for you? Each has several advantages and disadvantages. The main challenge is to institute a regular maintenance program to ensure that gaskets and valve seats get replaced on a regular schedule, every 6-24 months depending on production volumes, and that they are used within 5-10 years from their manufacturing date. Hopefully, this guide will help you select the best material for your application.

Buna-N

  • Refers to a large family of nitrile rubbers, a popular choice for automotive applications that come into contact with gasoline, oil, and/or greases present. It is also used for rubber gloves as it is less allergenic than latex.
  • Good resistance to oils, solvents, and fuels.
  • Good abrasion resistance, cold, and tearing.
  • Preferred for Nitrogen and Helium handling.
  • Poor resistance to UV, ozone, and weather.
  • Poor resistance to ketones and chlorinated hydrocarbons.
  • Inexpensive.
  • Important Note! Only Buna-N is approved for food and beverage applications, regular Buna is not approved as it releases particles when it breaks down. 

EPDM

  • A common polymer of ethylene and propylene, a diene is added so that it can be vulcanized for a longer lasting rubber. This allows for a better wear and tear resistance which is why it is a common selection for weather stripping and outside hoses.
  • Excellent heat, ozone, and weather resistance.
  • Good steam resistance. 
  • Excellent electrical resistance.
  • Good resistance to ketones, diluted acids, and alkalines.
  • Poor resistance to oil, gasoline, and kerosene.
  • Poor resistance to aliphatic hydrocarbons, halogenated solvents, and concentrated acids. 
  • Inexpensive.

FKM (Viton)

  • Branded under the trade name Viton, FKM is a fluorocarbon-based polymer with multiple carbon-fluorine bonds. FKM performs well in oxygen-enriched applications and can be found in SCUBA diving systems and other breathable air applications.
  • Good oil, grease, and fuel resistance. 
  • Good chlorinated hydrocarbon resistance. 
  • Performs well under a vacuum.
  • Excellent ozone, weather, and ageing resistance.
  • Poor cold resistance. 
  • Moderate cost.

Silicone

  • Silicone is a very stable, non-reactive, and resistant to extreme environments while still maintaining its properties. Due to this and the ease of manufacturing and shaping, it is used in many applications for food and beverage.
  • Good animal fat and vegetable oil resistance. 
  • Good chlorinated hydrocarbon resistance.
  • Moderate water and saline resistance.
  • Good ozone, ageing, and weathering resistance.
  • Poor physical resistance, should not be used in applications that are pressurized over one atmosphere or under a vacuum.
  • Moderate cost. 

    PTFE (Teflon)

    • PTFE is a fluorocarbon solid that is typically referred to by its tradename Teflon. It is very non-reactive, reduces friction, and interferes with the ability of bacteria to form biofilms. It is a common gasket fitting, but it is important to note it is a plastic and not a rubber material.
    • Excellent resistance to many chemicals.
    • Good reduction in friction in many applications.
    • Good heat resistance. 
    • A plastic gasket and not an elastic gasket, a constant pressure needs to be applied in order to ensure proper sealing. 
    • Cannot be removed and reused due to its more rigid physical nature. 
    • Moderate cost.
     Elastomer Dixon Part Code  Colour Code Fahrenheit Celcius
    Buna-N U 1 Red Dot -25 to 225 °F -32 to 107 °C
    Buna-N, White UW 1 Red Dot -25 to 225 °F -32 to 107 °C
    EPDM, Peroxide Cured E 3 Green Dots -40 to 275 °F -40 to 135 °C
    FKM (Viton) SFY 1 White Dot 
    +
    1 Yellow Dot
    -15 to 375 °F -26 to 191 °C
    Silicone, White XW 1 Pink Dot -50 to 400 °F -45 to 204 °C
    Silicone, Clear XC N/A -50 to 400 °F -45 to 204 °C
    PTFE (Teflon) G N/A -10 to 300 °F -23 to 149 °C
    PTFE with 50% 316 Particles GTS N/A -20 to 450 °F -29 to 149 °C
    Buna, Metal Detectable UZ 2 Blue Dots
    +
    1 Red Dot
    -30 to 200 °F -34 to 93 °C
    EPDM, Metal Detectable EZ 2 Blue Dots
    +
    3 Green Dots
    -20 to 300 °F -29 to 149 °C
    Silicone, Metal Detectable SFYZ 2 Blue Dots -40 to 450 °F -40 to 232 °C

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