O-rings
O-ring materials and compounds
An O-ring material is chosen by the media it seals first and the temperature second. The Parker® O-Ring Handbook (ORD 5700) pairs nitrile (NBR) with petroleum oils and hydraulic fluid, FKM with heat, fuels and chemicals, EPDM with water, steam and brake fluid, silicone with dry heat and cold in static service, and FFKM with media nothing else survives. On its standard ranges the families run from -73 C (fluorosilicone) to 320 C (FFKM), and the family chart on this page lists each range. Conquest supplies every family here in AS568 and metric sizes; name the compound or specification your print calls out, or the media, temperature and pressure, and we quote it.
- Compound families
- FKM, nitrile, EPDM, silicone, FFKM, HNBR, fluorosilicone, polyurethane, FEPM, PTFE, butyl, epichlorohydrin, ethylene-acrylic, natural rubber, neoprene, polyacrylate and SBR; the chart below lists each
- Hardness
- By compound or grade; for most applications the Parker handbook puts the usual choice at 70 to 80 Shore A (ORD 5700, page 2-10)
- Service temperature
- -73 C to 320 C by family on the Parker ranges (ORD 5700)
- Lowest service temperature
- fluorosilicone to -73 C standard; special silicone compounds to -115 C; Kalrez® 0040, the coldest FFKM grade cited here, to -42 C on its maker's sheet
- Highest service temperature
- FFKM to 320 C on the Parker service temperature table (ORD 5700, page 7-2); Kalrez 7075, the hottest grade cited here, to 327 C on its maker's sheet
- How to choose
- the compound or specification on your print; guides linked below
Service temperature by compound family
Each elastomer family has a published service range, and the Parker O-Ring Handbook (ORD 5700) ranges are the ones this site quotes. Standard FKM runs -26 C to 204 C, nitrile -34 C to 100 C, EPDM -57 C to 150 C, silicone -54 C to 204 C, fluorosilicone -73 C to 177 C, HNBR -32 C to 149 C, polyurethane -40 C to 82 C and FFKM -26 C to 320 C.
Special compounds stretch those limits. Low-temperature FKM reaches -46 C and steam-rated EPDM 204 C. Silicone special compounds run -115 C to 260 C, and named FFKM grades reach 327 C (Kalrez 7075) and -42 C (Kalrez 0040), each on its maker's sheet.
Hardness is set by the compound or grade, and its sheet states it. For most applications the Parker handbook puts the usual choice at 70 to 80 Shore A, with harder and softer compounds each paying a price in dynamic service (ORD 5700, page 2-10). PTFE has no family range in the handbook cited here, so its compound sheet governs; Aflas® runs -9 C to 232 C on the Parker ranges.
Media decides the family before temperature does: EPDM never sees petroleum oil, polyurethane never sees hot water, and FKM handles the fuels, oils and acids that swell the rest. The compound data sheet, not the family range, is the number to design to, and we send it with the quote. Tell us the compound or specification your print calls out and we quote the size in it.
| Family | Standard low | Standard high | Special grades | Hardness |
|---|---|---|---|---|
| FKM (Viton) | -26 C | 204 C | -46 C low-temperature; time-limited service to 232 C (Chemours C-11021) | 70 to 85 Shore A (seal makers' tables) |
| NBR (nitrile, Buna-N) | -34 C | 100 C | -57 C low-temperature; 121 C short term | 60 to 90 Shore A (seal makers' tables) |
| EPDM | -57 C | 150 C | 204 C steam compounds | By compound |
| VMQ (silicone) | -54 C | 204 C | -115 C; 260 C | 75 to 80 Shore A (seal makers' tables); others by compound |
| FVMQ (fluorosilicone) | -73 C | 177 C | no special grade published | By compound |
| FFKM | -26 C | 320 C | -42 C; 327 C named grades, each on its maker's sheet | By grade |
Compounds
O-ring materials at a glance
| Family | Pages | Standard range | Special grades | Durometers supplied | Note |
|---|---|---|---|---|---|
| FKM | Viton | -26 C to 204 C | to -46 C, to 232 C time-limited (about 3,000 hours) | 70 to 85 Shore A (seal makers' tables) | fuels, oils and heat; low-temperature grades to -46 C |
| NBR | Nitrile, Buna-N | -34 C to 100 C | to -57 C, to 121 C | 60 to 90 Shore A (seal makers' tables); 70 A default | mineral oils and hydraulic fluid; 121 C short term |
| EPDM | EPDM | -57 C to 150 C | to 204 C | By compound; the compound sheet states it | water, steam and glycol; never petroleum oil |
| VMQ | Silicone | -54 C to 204 C | to -115 C, to 260 C | 75 to 80 Shore A (seal makers' tables); other hardnesses by compound | dry heat and cold; static service |
| FFKM | FFKM, Kalrez, Chemraz®, Simriz® | -26 C to 320 C | to -42 C, to 327 C | By grade; the grade sheet states it | named grades reach 327 C (Kalrez 7075) and -42 C (Kalrez 0040), each on its maker's sheet |
| HNBR | HNBR | -32 C to 149 C | none listed | 75 to 80 Shore A (seal makers' tables) | oil with heat |
| FVMQ | Fluorosilicone | -73 C to 177 C | none listed | By compound; the compound sheet states it | fuels and oils at low temperature |
| AU/EU | Polyurethane | -40 C to 82 C | none listed | By compound; the compound sheet states it | abrasion and high pressure; never hot water |
| FEPM | Aflas | -9 C to 232 C | none listed | By compound; the compound sheet states it | steam, amines and sour gas; poor at low temperature |
| PTFE | PTFE | no family range stated | compound sheet governs | not applicable | an encapsulated ring is limited by the lower of its jacket and core |
| IIR | Butyl | -59 C to 121 C | none listed | By compound; the compound sheet states it | gas impermeability, brake fluid and phosphate esters; never oil |
| ECO | Epichlorohydrin | -40 C to 135 C | none listed | By compound; the compound sheet states it | the compound sheet governs |
| AEM | Ethylene-Acrylic | -40 C to 149 C | to 163 C | By compound; the compound sheet states it | hot automotive oil |
| NR | Natural Rubber | -50 C to 70 C | none listed | By compound; the compound sheet states it | the compound sheet governs |
| CR | Neoprene | -40 C to 121 C | none listed | By compound; the compound sheet states it | refrigerants, weather and moderate oil |
| ACM | Polyacrylate | -21 C to 177 C | none listed | By compound; the compound sheet states it | hot transmission oil; poor at low temperature and in water |
| SBR | SBR | -46 C to 100 C | none listed | By compound; the compound sheet states it | the compound sheet governs |
Ranges are the handbook family figures, not a guarantee for a specific compound. The SBR (dry heat), natural rubber (dry heat) and epichlorohydrin ranges are Apple Rubber's printed standard-compound figures (Apple Rubber Seal Design Guide, read 2026-09-27). Name the compound or specification your print calls out and we quote the size in it.
Source for the Viton 232 C figure: The Chemours Company, Viton Fluoroelastomers Selection Guide C-11021 (9/19), page 1, which gives it as a time-limited service limit of about 3,000 hours at 232 C (read 2026-09-27).
Material pages
One page per compound, with its grades and callouts
Viton O-Rings
-26 C to 204 C standard; 70 to 85 Shore A (seal makers' tables); 75 A default
Nitrile O-Rings
-34 C to 100 C standard; 60 to 90 Shore A (seal makers' tables); 70 A default
Buna-N O-Rings
-34 C to 100 C standard; 60 to 90 Shore A (seal makers' tables); 70 A default
EPDM O-Rings
-57 C to 150 C standard; By compound; the compound sheet states it
Silicone O-Rings
-54 C to 204 C standard; 75 to 80 Shore A (seal makers' tables); other hardnesses by compound
FFKM O-Rings
-26 C to 320 C standard; By grade; the grade sheet states it
Kalrez O-Rings
-26 C to 320 C standard; By grade; the grade sheet states it
HNBR O-Rings
-32 C to 149 C standard; 75 to 80 Shore A (seal makers' tables)
Fluorosilicone O-Rings
-73 C to 177 C standard; By compound; the compound sheet states it
Polyurethane O-Rings
-40 C to 82 C standard; By compound; the compound sheet states it
Aflas O-Rings
-9 C to 232 C standard; By compound; the compound sheet states it
PTFE O-Rings
No published family range; not applicable
Butyl O-Rings
-59 C to 121 C standard; By compound; the compound sheet states it
Chemraz O-Rings
-26 C to 320 C standard; By grade; the grade sheet states it
Epichlorohydrin O-Rings
-40 C to 135 C standard; By compound; the compound sheet states it
Ethylene-Acrylic O-Rings
-40 C to 149 C standard; By compound; the compound sheet states it
Natural Rubber O-Rings
-50 C to 70 C standard; By compound; the compound sheet states it
Neoprene O-Rings
-40 C to 121 C standard; By compound; the compound sheet states it
Polyacrylate O-Rings
-21 C to 177 C standard; By compound; the compound sheet states it
SBR O-Rings
-46 C to 100 C standard; By compound; the compound sheet states it
Simriz O-Rings
-26 C to 320 C standard; By grade; the grade sheet states it
Conductive elastomers for EMI shielding
Silver-aluminum, silver-copper, silver-glass and nickel-graphite fillers in silicone or fluorosilicone; MIL-DTL-83528 type letters; 45 to 85 Shore A in the manufacturer tables
EMI guides: groove, deflection and closure force and shielding effectiveness testing.
Selector
Find a seal material
Twenty-five O-ring and gasket materials rated against the media they meet most, with the continuous service range and the hardnesses each is supplied in. Pick a medium and your service temperatures to rank them, then open the material page or send the part for a quote.
Showing all 25 materials. Full compatibility matrix; choose a medium to rank.
| # | Material | Type | Verdict | Oil / grease | Fuels | Water / steam | Ozone / weather | Dilute acids | Ketones | Chlor. / aromatic solvents | Refrigerants | Brake fluid / Skydrol® | Continuous service range | Durometers | Links |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Nitrile O-RingsNBR (nitrile) | O-ring | Excellent | Good | Not recommended | Not recommended | Limited | Not recommended | Not recommended | Not rated | Not recommended | -34 to 100 C (-29 to 212 F); low-temperature compounds to -57 C; short term to 121 C | 60 to 90 Shore A (seal makers' tables, see note); 70 A default | Details: Nitrile O-Rings Request a quote for Nitrile O-Rings | ||
| Buna-N O-RingsNBR (nitrile) | O-ring | Excellent | Good | Not recommended | Not recommended | Limited | Not recommended | Not recommended | Not rated | Not recommended | -34 to 100 C (-29 to 212 F); low-temperature compounds to -57 C; short term to 121 C | 60 to 90 Shore A (seal makers' tables, see note); 70 A default | Details: Buna-N O-Rings Request a quote for Buna-N O-Rings | ||
| HNBR O-RingsHNBR (hydrogenated nitrile) | O-ring | Excellent | Excellent | Good | Good | Not rated | Not recommended | Not recommended | Good | Not rated | -32 to 149 C (-26 to 300 F) | 75 to 80 Shore A (seal makers' tables, see note) | Details: HNBR O-Rings Request a quote for HNBR O-Rings | ||
| Viton O-RingsFKM (fluorocarbon) | O-ring | Excellent | Excellent | Not recommended | Excellent | Good | Not recommended | Excellent | Not rated | Not recommended | -26 to 204 C (-15 to 400 F); low-temperature grades to -46 C | 70 to 85 Shore A (seal makers' tables, see note); 75 A default | Details: Viton O-Rings Request a quote for Viton O-Rings | ||
| FKM O-RingsFKM (fluoroelastomer) | O-ring | Excellent | Excellent | Not recommended | Excellent | Good | Not recommended | Excellent | Not rated | Not recommended | -26 to 204 C (-15 to 400 F); low-temperature grades to -46 C | 70 to 85 Shore A (seal makers' tables, see note) | Details: FKM O-Rings Request a quote for FKM O-Rings | ||
| Fluorosilicone O-RingsFVMQ (fluorosilicone) | O-ring | Good | Excellent | Not recommended | Excellent | Not rated | Not recommended | Good | Not rated | Not recommended | -73 to 177 C (-99 to 351 F) | By compound; the compound sheet states it | Details: Fluorosilicone O-Rings Request a quote for Fluorosilicone O-Rings | ||
| Silicone O-RingsVMQ (silicone) | O-ring | Not recommended | Not recommended | Limited | Excellent | Not rated | Not rated | Not rated | Not rated | Not rated | -54 to 204 C (-65 to 400 F); special compounds -115 C and 260 C | 75 to 80 Shore A (seal makers' tables, see note); other hardnesses by compound | Details: Silicone O-Rings Request a quote for Silicone O-Rings | ||
| EPDM O-RingsEPDM (ethylene propylene) | O-ring | Not recommended | Not recommended | Excellent | Excellent | Good | Good | Unsatisfactory | Not rated | Excellent | -57 to 150 C (-70 to 302 F); steam compounds to 204 C | By compound; the compound sheet states it | Details: EPDM O-Rings Request a quote for EPDM O-Rings | ||
| Polyurethane O-RingsAU / EU (polyurethane) | O-ring | Good | Good | Not recommended | Good | Not recommended | Not recommended | Not rated | Not rated | Not rated | -40 to 82 C (-40 to 180 F) | By compound; the compound sheet states it | Details: Polyurethane O-Rings Request a quote for Polyurethane O-Rings | ||
| Aflas O-RingsFEPM (tetrafluoroethylene-propylene) | O-ring | Good | Limited | Good | Not rated | Not rated | Limited | Limited | Not rated | Not rated | -9 to 232 C (16 to 450 F) | By compound; the compound sheet states it | Details: Aflas O-Rings Request a quote for Aflas O-Rings | ||
| FFKM O-RingsFFKM (perfluoroelastomer) | O-ring | Excellent | Excellent | Excellent | Not rated | Excellent | Excellent | Excellent | Not recommended | Not rated | -26 to 320 C (-15 to 608 F); named grades reach 327 C (Kalrez 7075) and -42 C (Kalrez 0040), each on its maker's sheet (Kalrez Product Selector Guide KZE-A40126, November 2022) | By grade; the grade sheet states it | Details: FFKM O-Rings Request a quote for FFKM O-Rings | ||
| Kalrez O-RingsFFKM (Kalrez) | O-ring | Excellent | Excellent | Excellent | Not rated | Excellent | Excellent | Excellent | Not recommended | Not rated | -26 to 320 C (-15 to 608 F); named grades reach 327 C (Kalrez 7075) and -42 C (Kalrez 0040), each on its maker's sheet (Kalrez Product Selector Guide KZE-A40126, November 2022) | By grade; the grade sheet states it | Details: Kalrez O-Rings Request a quote for Kalrez O-Rings | ||
| PTFE O-RingsPTFE (solid; FEP or PFA encapsulated) | O-ring | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | No published family range; the product sheet governs | not applicable | Details: PTFE O-Rings Request a quote for PTFE O-Rings | ||
| Butyl O-RingsIIR (butyl) | O-ring | Not recommended | Not recommended | Good | Not rated | Not rated | Not rated | Not recommended | Not rated | Good | -59 to 121 C (-74 to 250 F) | By compound; the compound sheet states it | Details: Butyl O-Rings Request a quote for Butyl O-Rings | ||
| Polyacrylate O-RingsACM (polyacrylate) | O-ring | Good | Not rated | Not recommended | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | -21 to 177 C (-6 to 351 F) | 80 Shore A (seal makers' tables, see note); other hardnesses by compound | Details: Polyacrylate O-Rings Request a quote for Polyacrylate O-Rings | ||
| Ethylene-Acrylic O-RingsAEM (ethylene-acrylic) | O-ring | Good | Not recommended | Not rated | Not rated | Not rated | Not recommended | Not rated | Not rated | Not recommended | -40 to 149 C (-40 to 300 F); shorter life to 163 C | By compound; the compound sheet states it | Details: Ethylene-Acrylic O-Rings Request a quote for Ethylene-Acrylic O-Rings | ||
| SBR O-RingsSBR (styrene-butadiene) | O-ring | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | -46 to 100 C (-50 to 212 F), dry heat; the compound sheet governs | By compound; the compound sheet states it | Details: SBR O-Rings Request a quote for SBR O-Rings | ||
| Natural Rubber O-RingsNR (natural rubber) | O-ring | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | -50 to 70 C (-58 to 158 F), dry heat; the compound sheet governs | By compound; the compound sheet states it | Details: Natural Rubber O-Rings Request a quote for Natural Rubber O-Rings | ||
| Epichlorohydrin O-RingsECO (epichlorohydrin) | O-ring | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | Not rated | -40 to 135 C (-40 to 275 F); the compound sheet governs | By compound; the compound sheet states it | Details: Epichlorohydrin O-Rings Request a quote for Epichlorohydrin O-Rings | ||
| Buna-N (Nitrile) Gasket MaterialNBR (nitrile) | Gasket | Excellent | Good | Not recommended | Not recommended | Limited | Not recommended | Not recommended | Not rated | Not recommended | -34 to 100 C (-29 to 212 F); low-temperature compounds to -57 C; short term to 121 C | Set by the sheet grade; the material page lists the sheets | Details: Buna-N (Nitrile) Gasket Material Request a quote for Buna-N (Nitrile) Gasket Material | ||
| EPDM Gasket MaterialEPDM (ethylene propylene) | Gasket | Not recommended | Not recommended | Excellent | Excellent | Good | Good | Unsatisfactory | Not rated | Excellent | -57 to 150 C (-70 to 302 F); steam compounds to 204 C | Set by the sheet grade; the material page lists the sheets | Details: EPDM Gasket Material Request a quote for EPDM Gasket Material | ||
| Neoprene Gasket MaterialCR (chloroprene) | Gasket | Good | Not rated | Limited | Good | Good | Not recommended | Not recommended | Excellent | Not rated | about -40 to 121 C (-40 to 250 F) | Set by the sheet grade; the material page lists the sheets | Details: Neoprene Gasket Material Request a quote for Neoprene Gasket Material | ||
| PTFE Gasket MaterialPTFE (virgin, filled, expanded) | Gasket | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | Grade sheet governs | No published family range; the grade sheet governs | not applicable (non-elastomer) | Details: PTFE Gasket Material Request a quote for PTFE Gasket Material | ||
| Silicone Gasket MaterialVMQ (silicone) | Gasket | Not recommended | Not recommended | Limited | Excellent | Not rated | Not rated | Not rated | Not rated | Not rated | -54 to 204 C (-65 to 400 F); special compounds -115 C and 260 C | Set by the sheet grade; the material page lists the sheets | Details: Silicone Gasket Material Request a quote for Silicone Gasket Material | ||
| Viton (FKM) GasketsFKM (fluorocarbon) | Gasket | Excellent | Excellent | Not recommended | Excellent | Good | Not recommended | Excellent | Not rated | Not recommended | -26 to 204 C (-15 to 400 F); low-temperature grades to -46 C | Set by the sheet grade; the material page lists the sheets | Details: Viton (FKM) Gaskets Request a quote for Viton (FKM) Gaskets |
Ratings are our own summary by material family: the nine media groups and the five-step scale are our arrangement, not a copy of any maker's chart, drawn mainly from the Parker O-Ring Handbook (ORD 5700) family descriptions and, for EPDM, Parker's compound data sheets; the compound datasheet governs. Hardness bands marked "seal makers' tables" span the published seal compounds in NOK Corporation's oil seal catalog 014E (read 2026-09-25; its lip-material table, which the approved bands cite, read 2026-09-16) and Freudenberg Sealing Technologies' rotary seals technical manual (read 2026-09-16); every other hardness is stated on the compound, grade or sheet datasheet. Temperature limits are continuous-service class ranges, and the special compounds named in the range column extend them. Not rated means no published family rating, not a pass. Unsatisfactory is the Parker handbook's own rating 4 (section VII fluid compatibility tables).
Viton is a trademark of The Chemours Company; Kalrez is a trademark of Qnity Electronics; Chemraz is a trademark of Greene Tweed; Simriz is a trademark of Freudenberg Sealing Technologies; Aflas is a trademark of AGC; Skydrol is a registered trademark of Solutia Inc. (the USPTO owner of record); Parker is a trademark of Parker Hannifin Corporation. No affiliation or endorsement is implied.
Frequently asked
What does Shore A hardness mean, and which hardness is usual?
Shore A is the indentation hardness scale for rubber; a higher number is a harder compound. For most applications the Parker handbook puts the usual choice at 70 to 80 Shore A (ORD 5700, page 2-10), and its stock O-ring kits are 70 A nitrile and 75 A FKM (page 3-6). Beyond that, hardness belongs to the compound: name it on the request and the compound sheet states it.
What is the difference between FKM and FFKM?
Both are fluorinated, but FFKM is fully fluorinated, so it resists chemistry that swells or attacks FKM; FFKM runs -26 C to 320 C on the Parker ranges, and named grades reach 327 C (Kalrez 7075) and -42 C (Kalrez 0040), each on its maker's sheet. Its hardness is set by the grade. Aerospace FFKM rings are specified to AMS7257, whose SAE title gives a 70 to 80 hardness band (SAE Mobilus record, read 2026-09-25), and the Parker handbook pairs its FF200-75 compound with that document (ORD 5700, Table 8-4, page 8-5, read 2026-09-24). FFKM is specified where the medium or the temperature rules the other families out.
When is fluorosilicone chosen over silicone?
When the seal sees fuel or oil at silicone temperatures. Silicone has poor resistance to petroleum fluids; fluorosilicone keeps most of the low-temperature flexibility (Parker ORD 5700 lists the family at -73 C to 177 C) and adds fuel and oil resistance. It is the aerospace fuel-system material, specified through AMS-R-25988 and the M25988 classes, and the Parker handbook pairs its 60, 70, 75 and 80 A fluorosilicone compounds with that document (Tables 8-3 and 8-4).
How do I read an ASTM D2000 callout such as M2BG710 B14?
It is a string of test requirements, not a material name. In the letter pair, the first letter is the type, set by resistance to heat aging, and the second is the class, set by resistance to swelling in oil (ASTM D2000 scope, read 2026-09-25); the digits and suffixes add further requirements whose values sit in the standard's own tables. A letter pair is an envelope that more than one family can meet, so read the family (NBR, FKM and so on under ASTM D1418) from the compound's datasheet.
Why does the temperature range vary inside one material family?
Because the range belongs to the compound, not the family. On the Parker handbook ranges, standard nitrile runs -34 C to 100 C, with low-temperature compounds to -57 C and short-term service to 121 C, and standard FKM starts at -26 C, with some compounds to -46 C. State the coldest start and the hottest continuous temperature on the request with the compound your print calls out, and ask for the datasheet with the quote.
Related guides
Orders are handled under Conquest Seal's AS9100D quality management system, whose certificate scope includes distribution.
Send the compound, the size and the quantity
Name the compound or specification your print calls out and we quote it and send the maker's data sheet. A Conquest representative replies. Quotes answered within one business day. A person answers (714) 632-9830, Pacific business hours.
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