Reference guide
O-Ring Temperature Ranges by Material
O-ring temperature range depends on the material family. On the Parker® O-Ring Handbook (ORD 5700) standard ranges, nitrile runs -34 C to 100 C, EPDM -57 C to 150 C, FKM (Viton®) -26 C to 204 C, silicone -54 C to 204 C and FFKM -26 C to 320 C, the widest standard span, and special compounds stretch several of these. The compound datasheet sets the final figure, and a temperature printed in a specification title is not an operating limit.
Every elastomer family has a working temperature window, and picking outside it is the surest route to compression set at the top end or a leaking, stiff ring at the bottom. The ranges below are the Parker O-Ring Handbook (ORD 5700) figures for each material family, with the special-compound extents the handbook lists; the compound datasheet is always the final word, and as the handbook puts it, specification temperature limits do not necessarily represent operating temperature limits. This guide tabulates the ranges, explains what happens at each end for each material, covers how temperature changes the gland design, and decodes the temperatures that appear in specification titles. Media decides the family before temperature does; see O-ring materials and compounds.
Temperature ranges by material
| Material | Standard continuous range | Special compounds | Source and note |
|---|---|---|---|
| Viton (FKM) | -26 C to 204 C (-15 F to 400 F) | low-temperature grades to -46 C (-51 F) | Parker ORD 5700; Viton grades are rated for time-limited service to 232 C (450 F) on the Chemours guide (C-11021) |
| Buna-N (NBR) | -34 C to 100 C (-29 F to 212 F) | low-temperature compounds to -57 C (-70 F); short term to 121 C (250 F) | Parker ORD 5700 |
| EPDM | -57 C to 150 C (-70 F to 302 F) | steam-rated compounds to 204 C (400 F) | Parker ORD 5700; Parker's E3609-70 drinking water and medical datasheet prints the same standard range |
| Silicone (VMQ) | -54 C to 204 C (-65 F to 400 F) | -115 C (-175 F) low-temperature; 260 C (500 F) high-temperature | Parker ORD 5700; static service |
| FFKM | -26 C to 320 C (-15 F to 608 F) | named grades to -42 C (-44 F) and 327 C (621 F) on their makers' sheets | Parker ORD 5700; grade sheets govern |
| HNBR | -32 C to 149 C (-26 F to 300 F) | per compound | Parker ORD 5700 |
| Fluorosilicone (FVMQ) | -73 C to 177 C (-99 F to 351 F) | per compound | Parker ORD 5700; static service |
| Polyurethane (AU/EU) | -40 C to 82 C (-40 F to 180 F) | hydrolysis in hot water above about 82 C | Parker ORD 5700 |
| Aflas® (FEPM) | -9 C to 232 C (16 F to 450 F) | per grade sheet; poor cold flexibility | Parker ORD 5700 section 2.2.14; steam, amines, sour gas |
| PTFE-encapsulated | The lower of the jacket and core figures | The grade sheet governs | |
What happens at each end of the range
The failure looks different by material and by end, which is what a teardown reads. The Parker handbook's compatibility and failure notes give the pattern.
| Material | Too cold | Too hot | Handbook alternative |
|---|---|---|---|
| Nitrile | Stiffens; low-acrylonitrile and low-temperature compounds reach -57 C | Hardens and takes set quickly past 100 C; ozone-like cracking after heat aging | HNBR to 149 C, FKM to 204 C |
| Viton (FKM) | Stiff below -26 C; leaks at cold start until it warms; low-temperature grades to -46 C | Tolerates short excursions above 204 C; hardens with prolonged heat | FFKM above the ceiling; silicone or fluorosilicone for cold; see the FFKM vs FKM guide |
| EPDM | Flexible to -57 C; one of the best cold materials | Standard compounds harden past 150 C; steam grades reach 204 C | FFKM steam grade where oil is also present |
| Silicone | Flexible to -54 C standard, -115 C special; the cold-service default | Dry heat to 204 C, 260 C special; steam degrades it | FKM where oil is present |
| FFKM | Deep cold is its weak point; -26 C standard, -42 C in one named grade on its maker's sheet | The widest hot range of the elastomers; named grades to 327 C on their makers' sheets | Low-temperature FKM for cold |
| Fluorosilicone | Flexible to -73 C | Hot air resistance worse than silicone; 177 C ceiling | FKM for heat with fuel |
| Polyurethane | Flexible to -40 C | Hydrolyzes in hot water above about 82 C | Nitrile or HNBR |
These are published manufacturer guidelines, not Conquest Seal recommendations; Conquest quotes the material your print names.
How temperature changes the gland, not just the material
Temperature moves the published squeeze band in both directions. A ring expands into its gland when hot and shrinks away from it when cold, so hot service argues for the low end of the published squeeze band and cold service for the high end. The O-ring groove design guide covers the void left for thermal expansion. A wide temperature swing calls for a compound with low compression set, since set taken in the expanded state leaves nothing when the ring contracts.
The squeeze guide and the compression set guide cover both effects.
Temperatures in specification titles are not operating limits
Several seal specifications carry a temperature in their own title, and buyers read them as service ratings. They are test conditions or glass-transition figures for the document, read from the DLA ASSIST and SAE Mobilus records on 2026-09-24, 2026-09-25 and 2026-09-27, and the Parker handbook's caution applies to all of them.
| Document | Temperature in the title | What it is |
|---|---|---|
| MIL-PRF-25732 (MS28775 nitrile) | The government and SAE documents print different figures in their titles | A service-class label, not a compound rating; cite the document, not the number |
| MIL-P-83461 / AMS-P-83461 (M83461/1 nitrile) | An improved-performance class in the title | A test class; the compound sheet gives the range. The size sheet MIL-P-83461/1 was cancelled on 2003-10-01 in favor of SAE-AMS-P-83461/1, which DLA ASSIST records as withdrawn on 2010-01-20 in favor of SAE-AS83461/1, now at revision C (reaffirmed 2021-11-08) |
| AMS7379 (fluorocarbon) | A -40 F glass transition in the title | A low-temperature FKM grade marker, not a continuous rating |
| AMS7276, AMS7280, AMS7259 (fluorocarbon) | None | "High temperature" in the title names the service class; the Parker FKM range applies |
| AMS 7257 (FFKM) | None | "High temperature fluid resistant"; the Parker FFKM range applies |
How to specify temperature on an RFQ
Give the continuous operating temperature, the peak and how long it lasts, the minimum (including storage and cold start), whether the seal is static or dynamic, and the medium, because the medium's swell adds to thermal expansion in the gland. A material chosen at the edge of its range needs a low-set compound and the right end of the squeeze band; a material chosen in the middle of its range forgives the gland. Two standing cautions: EPDM must never see petroleum oils regardless of temperature, and silicone's headline range applies to static service only. For head-to-head choices, start with FKM vs silicone, EPDM vs FKM or fluorosilicone vs FKM.
Viton is a trademark of The Chemours Company; Aflas is a trademark of AGC Inc.; Parker is a trademark of Parker Hannifin Corporation. No affiliation or endorsement is implied.
Sources
- Parker O-Ring Handbook ORD 5700, service temperature table, page 7-2 (FFKM -26 C to 320 C), read 2026-09-25
- Parker O-Ring Handbook ORD 5700, section 2.2 (elastomer heat and cold figures), read 2026-09-14
- Chemours, Viton Fluoroelastomers Selection Guide C-11021 (9/19), page 1: about 3,000 hours at 232 C (450 F), a time-limited service limit, read 2026-09-27
- Parker compound E3609-70 drinking water and medical datasheet, read 2026-08-13
- Qnity Electronics FFKM product selector guide KZE-A40126 (Nov 2022), read 2026-09-14
- DLA ASSIST and SAE Mobilus records for MIL-PRF-25732, MIL-P-83461, AMS-P-83461, AMS7276, AMS7280 and AMS7259 (read 2026-09-24) and AMS7379 and AMS 7257 (read 2026-09-25)
- DLA ASSIST records for MIL-P-83461/1 (ident 33814, cancelled 2003-10-01), read 2026-09-24, and SAE-AMS-P-83461/1 (withdrawn 2010-01-20, superseded by SAE-AS83461/1), read 2026-09-25; SAE Mobilus AS83461/1C current-revision record, read 2026-09-27
- ASTM D2000-18(2024)e1, ASTM store listing (title and public scope: types by heat-aging resistance, classes by oil swell), read 2026-09-25
Frequently asked questions
Which O-ring material has the widest temperature range?
FFKM, on the standard ranges in the Parker O-Ring Handbook (ORD 5700): it runs -26 C to 320 C, while standard silicone runs -54 C to 204 C. Silicone spans more only when its special compounds are counted: a low-temperature compound reaches -115 C and a high-temperature compound 260 C, in static service. Fluorosilicone has the lowest standard cold figure at -73 C, and deep cold is the weak end of FFKM.
Can an O-ring exceed its rating briefly?
The handbook allows short excursions for some families (FKM above 204 C, nitrile to 121 C); each excursion takes some set, and the compound sheet says how much.
Why did the seal leak on a cold morning and stop by noon?
The ring shrank away from the gland below its flexible range and recovered as it warmed. Raise the squeeze toward the top of the band or move to a lower-temperature compound.
Is a spec temperature a guarantee?
No. A figure in a specification title is a test class or a glass transition for that document; the Parker handbook's own caution is that spec limits do not necessarily represent operating limits.
Where do these numbers come from?
The Parker O-Ring Handbook compound table (ORD 5700, section 2.2), including Aflas (FEPM) at -9 C to 232 C. Materials with no handbook range (PTFE-encapsulated) are left to the grade sheet.
How wide is the spread inside one family?
Wide enough to matter. On the Parker handbook figures this guide lists, standard nitrile runs down to -34 C while low-temperature nitrile compounds reach -57 C, and standard FKM stops at -26 C while low-temperature grades reach -46 C. Order by compound, not by family, when the cold end matters.
Which family reaches the highest continuous temperature?
Perfluoroelastomer. On the Parker handbook ranges FFKM runs -26 C to 320 C, and a brand grade sheet runs to 327 C. FKM reaches 204 C, silicone 204 C, ethylene acrylic 149 C (163 C with shorter life), EPDM 150 C, nitrile 100 C (121 C short term) and polyurethane 82 C. Viton grades are rated for time-limited service to 232 C (450 F) on the Chemours guide (C-11021).
Does a D2000 type letter tell me the service temperature?
No. ASTM D2000 sets the type letter by resistance to heat aging, a test condition, not a service rating. A compound that passes the test is not rated to run at that temperature continuously; the datasheet's service range is the number to use.
Related guides
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