Why O-Rings Come in Different Colors

O-rings are circular seals made from various elastomers, used extensively for sealing applications in industries ranging from automotive and hydraulics to food processing and pharmaceuticals. While black is the most common color, O-rings are available in a wide range of colors — and they often signify the type of material and its application.

Color coding simplifies identification and selection, helping technicians quickly recognize the material and its resistance profile without the need for chemical testing. However, it is crucial to note: color alone should never be the sole selection criterion.

Common O-Ring Colors and Their Meanings

Black O-Rings

• Typical Material: NBR (Nitrile Butadiene Rubber), EPDM, FKM

• Applications: General-purpose sealing in automotive, hydraulics, pneumatics

• Properties: Oil-resistant (NBR), weather/ozone-resistant (EPDM), or chemically resistant (FKM)

White O-Rings

• Typical Material: PTFE (Teflon), Silicone

• Applications: Food, pharmaceutical, and cosmetic industries

• Properties: Chemically inert, food-grade compliant (FDA), heat resistant

Red/Copper O-Rings

• Typical Material: Silicone (VMQ or MVQ)

• Applications: HVAC, food contact, medical

• Properties: Excellent thermal stability, flexibility at low temperatures

Blue O-Rings

• Typical Material: FKM (Viton®), EPDM

• Applications: Chemical processing, food-grade (often metal detectable)

• Properties: High chemical resistance, high temperature range

Green O-Rings

• Typical Material: HNBR, FKM

• Applications: Automotive, refrigerants, air conditioning systems

• Properties: Good resistance to heat, oil, and chemicals

Brown O-Rings

• Typical Material: FKM (Viton®)

• Applications: Fuel systems, aerospace, oil & gas

• Properties: Outstanding chemical resistance and high-temperature durability

Transparent/Clear O-Rings

• Typical Material: Silicone

• Applications: Laboratory equipment, food and beverage

• Properties: Odorless, tasteless, flexible, FDA-grade

Less Common O-Ring Colors

• Yellow: Silicone or EPDM; used in steam systems, boilers

• Gray: FKM or NBR; used in fuel systems

• Beige/Natural: FFKM (Kalrez®); pharmaceutical-grade, extreme chemical resistance

• Purple: EPDM or MVQ; typically for specialty food or beverage use

• Silver: Viton® or FKM with metal additives

• Graphite/Black-Grey: FFKM for aerospace or aggressive media

How to Choose the Right O-Ring Material (Color is Not Enough)

While color is a useful identifier, always consult the material specifications:

• Check chemical compatibility with operating media

• Review temperature range and pressure conditions

• Verify certification (e.g., FDA, WRAS, NSF) if required

• Assess abrasion, ozone, and weather resistance

Conclusion: Color is a Helpful Guide, But Not a Guarantee

O-ring colors are incredibly useful for visual identification and inventory management. However, the same color might represent different materials depending on the manufacturer. Always confirm the compound specification before use, especially in safety-critical or regulated applications.

For trusted, high-quality O-rings in all colors and materials – including NBR, FKM, EPDM, and more – visit simmering.pl.

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