FFKM−15 to 270 °C5 to 518 °F
Material guide · 11 families
O-ring materials: choose the family, then confirm the compound
Short answer: NBR for oil and hydraulics, FKM for heat and fuel, EPDM for water, steam and weather, silicone for wide temperature static seals, and FFKM when chemicals attack everything else.
I need a seal for
Pick a need to highlight the families that fit across the page.
Service temperature
Typical temperature range by family
Typical across 651 compound records reviewed; the supplied compound decides. Ranges are published only where at least 10 records state one.
Temperature guide → Continuous vs peak temperature, media, pressure, motion and thermal cycling.
Scale
Solid bar = typical span of the family (median low to median high). Lighter whisker = 25th to 75th percentile, where wider-range grades reach. Sorted hottest first: 1 FFKM, 2 FKM, 3 Silicone, 4 FVMQ, 5 EPDM, 6 CR, 7 NBR. The FFKM bar is a screening reference, not an operating rating for every grade.
FKM−25 to 225 °C−13 to 437 °F
Silicone−55 to 200 °C−67 to 392 °F
FVMQ quote−70 to 175 °C−94 to 347 °F
EPDM−55 to 120 °C−67 to 248 °F
CR quote−40 to 120 °C−40 to 248 °F
NBR−30 to 120 °C−22 to 248 °F
- HNBR (Hydrogenated nitrile): quote only — too few records state a service range, and it differs by compound. Ask for HNBR
- FEPM (TFE/P): quote only — too few records state a service range, and it differs by compound. Ask for FEPM
- PU (Polyurethane): quote only — too few records state a service range, and it differs by compound. Ask for PU
- PTFE (PTFE): quote only — too few records state a service range, and it differs by compound. Ask for PTFE
Type a temperature, or focus a bar, to compare. Hover or focus a bar for the exact range and the number of records behind it.
Table view: exact ranges and record counts
| Family | Typical °C | Typical °F | Wider-range grades °C | Records |
|---|---|---|---|---|
| NBR | −30 to 120 °C | −22 to 248 °F | −40 to 120 °C | 92 |
| FKM | −25 to 225 °C | −13 to 437 °F | −35 to 225 °C | 64 |
| EPDM | −55 to 120 °C | −67 to 248 °F | −55 to 145 °C | 50 |
| Silicone | −55 to 200 °C | −67 to 392 °F | −55 to 230 °C | 21 |
| FFKM | −15 to 270 °C | 5 to 518 °F | −20 to 320 °C | 44 |
| FVMQ | −70 to 175 °C | −94 to 347 °F | Same as typical | 21 |
| CR | −40 to 120 °C | −40 to 248 °F | −45 to 120 °C | 16 |
Uses 330 of 651 compound records: the rest state no service range. The typical bar spans the median minimum to the median maximum; the lighter line spans the 25th to the 75th percentile, where it differs. A range is shown only for families with at least 10 records.
Material families
Five families in the catalog, six more on request
NBR, FKM, EPDM, silicone and FFKM are listed by exact size in small packs. HNBR, fluorosilicone, chloroprene, FEPM, polyurethane and PTFE are made to order.
NBR Nitrile · Buna-N
Nitrile
The general-purpose seal for oil, hydraulic and pneumatic systems.
Good starting point for
- Mineral oils, hydraulic fluids and greases
- Many fuels at moderate temperature
- Water and air below about 100 °C
Check carefully
- Ozone, sunlight and outdoor exposure
- Glycol brake fluid, ketones and esters
- Heat above about 120 °C
- Typical temp.
- −30 to 120 °C −22 to 248 °F
- Hardness
- 60/70/80/90 Shore A listed
- Specific gravity
- 1.27
- Tensile · elongation
- 14 MPa · 280% median
- Compound records
- 124
FKM Fluoroelastomer · FPM
Fluoroelastomer
Heat, fuel and chemical resistance in one family; the usual step up from NBR.
Good starting point for
- Fuels, oils and lubricants at elevated temperature
- Many acids and aromatic or chlorinated solvents
- Long static service with low compression set
Check carefully
- Ketones, esters, amines and glycol brake fluid
- Hot water and steam with standard grades
- Cold: standard grades stiffen around −20 °C
- Typical temp.
- −25 to 225 °C −13 to 437 °F
- Hardness
- 70/75/80/90 Shore A listed
- Specific gravity
- 1.87
- Tensile · elongation
- 13 MPa · 200% median
- Compound records
- 153
EPDM Ethylene propylene diene
Ethylene propylene
The water-and-weather family: water, steam, glycol and outdoor service.
Good starting point for
- Hot water, steam and glycol coolants
- Glycol brake fluid and many phosphate ester fluids
- Ozone, UV and weathering
Check carefully
- Any mineral oil, fuel or petroleum grease
- Hydrocarbon solvents
- Food or drinking water: needs a documented compound
- Typical temp.
- −55 to 120 °C −67 to 248 °F
- Hardness
- 70/80 Shore A listed
- Specific gravity
- 1.18
- Tensile · elongation
- 13 MPa · 280% median
- Compound records
- 84
Silicone Silicone · VMQ
Silicone
The widest temperature span of the common families, best in static seals.
Good starting point for
- Dry heat and deep cold in static seals
- Air, ozone and weathering
- Clean, low-odour applications (compound dependent)
Check carefully
- Abrasion, tear and dynamic motion
- Petroleum fuels, mineral oils and steam; screen other oils against the exact compound and conditions
- High gas permeability
- Typical temp.
- −55 to 200 °C −67 to 392 °F
- Hardness
- 70 Shore A listed
- Specific gravity
- 1.26
- Tensile · elongation
- 7 MPa · 250% median
- Compound records
- 105
FFKM Perfluoroelastomer
Perfluoroelastomer
The broadest chemical resistance of any rubber family, at the highest cost.
Good starting point for
- Aggressive chemicals, solvents and mixed process media
- Temperatures beyond the FKM grade
- Process seals where downtime costs more than the ring
Check carefully
- Cost, often many times FKM
- Cold flexibility and large differences between grades
- Molten alkali metals and some fluorinated fluids
- Typical temp.
- −15 to 270 °C 5 to 518 °F
- Hardness
- 60/70/75/80/90 Shore A listed
- Specific gravity
- 1.98
- Tensile · elongation
- 16 MPa · 150% median
- Compound records
- 82
FFKM −15 to +270 °C is a grade-dependent reference, not a guaranteed operating range for every SKU. Confirm the compound, medium and continuous-service temperature; grades differ in heat, steam and chemical resistance.
On request
HNBR Hydrogenated nitrile
Hydrogenated nitrile
FVMQ Fluorosilicone
Fluorosilicone
CR Chloroprene · polychloroprene
Chloroprene
FEPM FEPM · TFE/P
TFE/P
PU Polyurethane · AU/EU
Polyurethane
PTFE Fluoropolymer · not a rubber
PTFE
Compare two materials
A vs B, side by side
Pick any two of the 11 families. You get both data plates and where each one is a good starting point or needs a closer check.
Comparing NBR and FKM.
NBR Nitrile
The general-purpose seal for oil, hydraulic and pneumatic systems.
- Typical temp.
- −30 to 120 °C−22 to 248 °F
- Hardness
- 60–90 ShAListed grades
- Specific gravity
- 1.27
- Tensile
- 14 MPa2,100 psi
- Elongation
- 280 %At break
FKM Fluoroelastomer
Heat, fuel and chemical resistance in one family; the usual step up from NBR.
- Typical temp.
- −25 to 225 °C−13 to 437 °F
- Hardness
- 70–90 ShAListed grades
- Specific gravity
- 1.87
- Tensile
- 13 MPa1,900 psi
- Elongation
- 200 %At break
NBR
Good starting point for
- Mineral oils, hydraulic fluids and greases
- Many fuels at moderate temperature
- Water and air below about 100 °C
Check carefully
- Ozone, sunlight and outdoor exposure
- Glycol brake fluid, ketones and esters
- Heat above about 120 °C
Typical range across compounds reviewed: −30 to 120 °C (−22 to 248 °F).
FKM
Good starting point for
- Fuels, oils and lubricants at elevated temperature
- Many acids and aromatic or chlorinated solvents
- Long static service with low compression set
Check carefully
- Ketones, esters, amines and glycol brake fluid
- Hot water and steam with standard grades
- Cold: standard grades stiffen around −20 °C
Typical range across compounds reviewed: −25 to 225 °C (−13 to 437 °F).
Selection note
The most common upgrade. NBR is the economical default for mineral oil and hydraulics up to roughly 100–120 °C. Move to FKM when the fluid runs hotter, when fuel contains aromatics or blends, or when compound-specific compression-set performance is important for long static service. Material family alone does not establish service life; review medium, temperature, formulation and validation. Watch cold starts: standard FKM stiffens well before NBR does.
Hardness · Shore A
Which hardness to pick
Hardness changes how much force the ring needs to seal, how well it resists extrusion, and how much friction it adds. The family sets the chemistry; hardness sets the mechanics.
50Shore A
Very soft
0 configurations at this grade
- What changes
- Seals with very little clamp force and conforms to rough, uneven or fragile faces.
- Pick it for
- Light static seals, thin covers and low pressure where the hardware cannot squeeze hard.
On requestCheck the gland
60Shore A
Soft
1,254 configurations at this grade
- What changes
- Lower closing force than 70A, with better conformance to an imperfect surface.
- Pick it for
- Low-pressure static seals with light or soft flanges.
70Shore A
General purpose
29,980 configurations at this grade
- What changes
- The balance point of sealing force, extrusion resistance and friction used by most gland tables.
- Pick it for
- A common starting point for many static and reciprocating seals after reviewing medium, temperature, compound, pressure, extrusion gap and motion; not the correct first trial for every application.
75Shore A
Standard fluoro grade
23,829 configurations at this grade
- What changes
- A little firmer than 70A in the same gland; the common standard grade in FKM and FFKM.
- Pick it for
- Fluoro sizes that are only listed at 75A.
80Shore A
Firm
12,358 configurations at this grade
- What changes
- Better extrusion resistance at higher pressure or a wider gap, with more friction and more installation force.
- Pick it for
- Higher pressure, larger clearance gaps, or a seal that nibbles in motion.
90Shore A
Hard
10,322 configurations at this grade
- What changes
- The highest extrusion resistance, and the hardest to install and seat.
- Pick it for
- High-pressure hydraulics, pressure spikes and rough dynamic duty.
- Use 70A, or common 75A fluoro grades, as starting candidates where appropriate; review medium, temperature, compound, pressure, extrusion gap and motion before choosing hardness.
- Move up to 80A–90A for higher pressure, larger clearance gaps or seals that nibble in motion; add a backup ring when the gap is large.
- Move down to 50A–60A when clamp force is low, the faces are rough or soft, or the pressure is low.
- Hardness tolerance is typically ±5 points and small cross-sections test differently: treat the number as a class, not an exact value.
FAQ
Material questions we answer most
Still unsure? Send the media, temperature, pressure and motion and we reply with a family and compound suggestion.
What is the best general-purpose O-ring material?
For oil, hydraulic fluid, air and water below about 100 °C, NBR 70A is the usual starting point. For water, steam, brake fluid or outdoor use, start with EPDM instead. Screen the actual media with the chemical tool before ordering.
When is FKM worth the extra cost over NBR?
When the seal runs hotter than NBR tolerates (roughly above 100–120 °C), sees fuel with aromatics or blends, or must hold a static seal for a long time with little compression set. For cool mineral-oil service NBR is usually enough.
Which O-ring material handles the highest temperature?
Among the families we list, FFKM has the highest typical upper range, followed by FKM and silicone. The limit for your seal depends on the compound, the media, pressure and motion, so keep a margin below the published value.
Which material should I use for water and steam?
EPDM is the usual choice for hot water, steam and glycol coolants. It must not contact mineral oil or petroleum grease. For steam mixed with chemicals, FFKM or FEPM are options to review.
Can I use these O-rings for food or drinking water?
The material family alone does not make a seal compliant. Food-contact or drinking-water use needs a specific compound with documentation for your market. Our catalog listings do not claim this; ask for a documented compound when you request a quote.
What does Shore A hardness mean for an O-ring?
It measures how hard the rubber is. 70A is a common general-purpose starting candidate, subject to medium, compound and service conditions; 80A–90A resists extrusion at higher pressure but needs more force to seal; 50A–60A seals with less force on rough faces. Tolerance is typically ±5 points.
Are the temperature ranges on this page guaranteed?
No. They are typical ranges across the compound records we reviewed, rounded inward to 5 °C, and only shown where enough records exist. The compound you receive and the service conditions decide the real limit.
Claims & sources
- Material guidance here is family-level screening, not approval of a compound. The compound you receive, its cure system and its filler decide the real limits.
- Temperature, hardness, specific gravity, tensile and elongation figures are medians and typical spans across 651 anonymised compound records from our internal reference set. Temperature is published only for families with at least 10 records stating a service range (7 of 11 families), rounded inward to 5 °C.
- Chemical answers on the linked tool are screening only. Standard size references (AS568, ISO, JIS, BS) are public references, not an official validation.
- Food-contact, drinking-water and other regulatory compliance belongs to a specific compound and must be documented for your market. Catalog listings make no such claim.
- Tool results are geometry and reference checks, not an engineering approval. For critical service, send the conditions for an engineering review.