O-rings are everywhere—from your home appliances to heavy industrial machinery and even deep-sea equipment. But picking the wrong one isn’t just a minor mistake. It can lead to leaks, downtime, and serious safety hazards. Real-world examples drive this home: one chemical plant lost over 100,000 RMB in materials after NBR O-rings swelled and failed within three hours in ketone-based solvents. Another manufacturer saw seals fail and pipes freeze-crack in a week at -30°C because they used standard FKM instead of a low-temperature grade.
1. Nitrile Rubber (NBR): The Affordable Oil-Resistant Workhorse
This is the go-to, cost-effective choice for general oil resistance.
What it handles well:
Temperature: Performs reliably from -30°C to 120°C. It can handle a short spike to 150°C, but ages rapidly if constantly used above 120°C.
Media: Great with petroleum-based oils (engine, hydraulic, diesel), water, and weak acids (<10% sulfuric/hydrochloric).
What it hates:
Keep it away from ketones (like acetone), esters, and aromatic hydrocarbons (benzene, toluene). It will swell and fail quickly. Tests show 35% volume increase in acetone after just 24 hours.
Also avoid gasoline lines for the same reason.
Best used for:
Automotive engine bay applications (oil/fuel lines in non-extreme heat areas).
Hydraulic systems running under 100°C.
Household appliances like washing machines and range hoods (keep away from sustained high heat >150°C near stovetops).
2. Fluorocarbon Rubber (FKM): The High-Temp, Chemical-Resistant All-Rounder
When things get hot or the chemicals get tricky, FKM is usually the answer.
What it handles well:
Temperature: Standard grades cover -20°C to 200°C, with low-temp versions down to -30°C. Can briefly withstand up to 230°C.
Media: Excellent resistance to oils, most solvents (ethanol, toluene), and weak acids/bases (<30%).
In testing, it showed only 18% compression set after 1000 hours in 150°C hot oil, far outperforming NBR.
What it hates:
Small ketones (acetone), amines (ammonia), esters, and some specialty fluids can attack it.
Best used for:
Automotive turbochargers (high-temp oil/vapor around 180-200°C).
Chemical processing equipment (flanges, reactors with mild corrosives up to ~150°C).
High-temperature hot water and steam lines.
Key selection tip:
For outdoor use in cold climates (<-20°C), specify a low-temperature grade to prevent hardening.
It becomes cost-effective vs. NBR when temperatures consistently exceed 120°C or with complex media, offering 3-5x longer life.
3. Silicone Rubber (VMQ): Unbeatable for Temperature Range, But Keep It Dry
Silicone excels where extreme temperatures or purity are needed, but it's picky about its environment.
What it handles well:
Temperature: Its biggest strength, from a frigid -60°C up to 200°C.
Media: Ideal for water, steam, air, and food-grade applications (use certified grades).
Elasticity: Superb, staying flexible at -50°C when NBR turns brittle.
What it hates:
Petroleum-based oils and greases—they cause swelling and degradation.
Poor abrasion resistance makes it a bad choice for dynamic sealing (like rotating shafts).
Best used for:
Low-temperature sealing: freezer doors, refrigerated transport.
Food & medical applications: water dispensers, medical device connectors (must use certified grades).
Appliance steam seals (irons, microwokes) where oils aren't present.
Key selection tip:
Always verify if you need an "Industrial" or "Food/Medical" grade—the latter requires proper certification (FDA, LFGB).
4. Hydrogenated Nitrile (HNBR): Like NBR, But Tougher and Longer-Lasting
Think of HNBR as NBR's more durable cousin, with better heat, ozone, and wear resistance.
Where it improves on NBR:
It keeps the good oil resistance but significantly boosts performance against heat aging, ozone cracking (great for outdoors), and abrasion—almost matching FKM in wear.
Tested in 120°C transmission fluid, it retained 85% of its strength vs. NBR's 60%.
Best used for:
Demanding automotive uses like automatic transmissions (hot oil + vibration).
Oilfield equipment exposed to sour gas (H₂S).
As a cost-saving alternative to FKM in oil-resistant applications under 150°C, costing about 40% less.
Key selection tip:
Remember, its upper temperature limit (~150°C) is still below FKM's (200°C). Don't push it in truly high-heat scenarios.
5. Perfluoroelastomer (FFKM): The "Last Resort" for Extreme Conditions
This is the top-tier material for when nothing else works. Its performance is phenomenal, and so is its price.
What it handles (which is almost everything):
Temperature: From -20°C to an incredible 350°C.
Media: Resistant to virtually all chemicals, including aggressive acids like aqua regia, conc. sulfuric, and hydrofluoric acid. It survives boiling in 98% sulfuric acid for days.
Best used for (and only for):
Extreme environments only: Aerospace fuel systems, semiconductor etching (HF gas), nuclear industry applications.
Critical advice:
Never use FFKM for standard applications. FKM is sufficient for most chemical plants. FFKM's value is only realized where every other material fails immediately.
Handle with extreme care during installation. It's stiffer (>70 Shore A), and over-stretching can cause permanent damage, leading to leaks.
Post time: Jan-20-2026