O-ring material
EPDM O-Rings
EPDM O-rings seal water, steam, glycol brake fluid, phosphate-ester hydraulic fluid and outdoor equipment, and never petroleum oil. The Parker® O-Ring Handbook (ORD 5700) rates the family from -57 C to 150 C, with steam-rated compounds to 204 C. Conquest supplies EPDM O-rings in every AS568 and metric size, including compounds their makers list as FDA compliant and NSF listed for drinking water, and the ethylene propylene compound the NAS1613 aerospace callout names.
- Family
- EPDM (ethylene propylene diene rubber, ASTM D1418)
- Standard range
- -57 C to 150 C (Parker O-Ring Handbook ORD 5700)
- Special grades
- steam-rated compounds to 204 C (Parker ORD 5700)
- Durometers
- 60 to 90 Shore A across the EPDM compounds Parker's handbook catalogues (Table 8-5); the handbook puts 70 to 80 A as the right range for most applications (page 2-10)
- Standards
- ASTM D1418 EPDM; ASTM D2000 M3CA on the E3609-70 sheet; NAS1613 (phosphate-ester resistant O-ring packing); FDA 21 CFR 177.2600, NSF/ANSI 51 and 61, USP Class VI on specific compounds
- Product
- O-rings in AS568 and ISO 3601 sizes, quoted in the compound the print names
Service temperatures here are the family figures published in Parker O-Ring Handbook ORD 5700A/US §2.2; the compound datasheet and your application govern the final choice.
Larger and non-standard sizes: an O-ring beyond the molded size lists can be supplied as a spliced and vulcanized O-ring, which the maker joins from cord of the same compound. That page lists, family by family, which makers offer the compound as cord, and what to send for a quote.
What EPDM is
EPDM is the ASTM D1418 designation for ethylene propylene diene rubber; EPM and EPR are the copolymer forms without the diene. The polymer backbone is saturated, which is why it shrugs off ozone, sunlight and heat that crack nitrile, and its chemistry is why polar media (water, steam, glycols, ketones, alcohols) leave it alone while petroleum products swell it. EPDM is cured with sulfur or with peroxide; peroxide-cured compounds are the usual choice for steam, hot water and potable-water listings because of their lower compression set and cleaner extractables. The one hard rule: keep it away from petroleum oils, greases and fuels, even as an assembly lubricant.
EPDM compounds by type
Most prints name EPDM and a hardness, or a listing, and leave the compound to the datasheet. The temperature figures below are the Parker O-Ring Handbook (ORD 5700) family range; the Parker E3609-70 drinking-water compound datasheet prints -57 C to 150 C continuous for that compound; its E3609-70 FDA sheet prints -70 F to 250 F (-57 C to 121 C) and its E3609-70 ISO 10993 sheet -65 F to 250 F (-54 C to 121 C).
| Compound type | Cure | Typically chosen for | Temperature range (Parker ORD 5700) | Listings on specific compounds |
|---|---|---|---|---|
| General-purpose EPDM | Sulfur or peroxide | Water, coolant, weather and outdoor service, general industrial | -57 C to 150 C | None required |
| Steam and hot-water EPDM | Peroxide | Steam lines, autoclaves, clean-in-place process equipment | Steam-rated compounds to 204 C | Per compound |
| Potable-water and food EPDM | Peroxide, typically | Drinking-water valves and fittings, food equipment | -57 C to 150 C; the E3609-70 datasheet prints -57 C to 150 C continuous and up to 204 C in water and steam | NSF/ANSI 61, NSF/ANSI 51, FDA 21 CFR 177.2600, KTW, WRAS |
| Medical-grade EPDM | Peroxide | Pharmaceutical and device service with repeated steam, gamma or ethylene-oxide sterilization | -57 C to 121 C (-70 F to 250 F) on the E3609-70 FDA sheet and -54 C to 121 C (-65 F to 250 F) on the E3609-70 ISO 10993 sheet; the family range is -57 C to 150 C (Parker ORD 5700) | USP Class VI, USP 87, ISO 10993-5 and -10 reports |
| Phosphate-ester (aerospace) EPDM | Per the compound | Aircraft hydraulic systems on phosphate-ester fluid | -57 C to 150 C (family range) | NAS1613 material callout |
EPDM O-ring specifications
| Property | Value | Source |
|---|---|---|
| Continuous service temperature | -57 C to 150 C (-70 F to 302 F); steam-rated compounds to 204 C | Parker ORD 5700; the Parker E3609-70 drinking-water datasheet prints the same range (its FDA and ISO 10993 sheets print 250 F) |
| Material designation | EPDM under ASTM D1418; the E3609-70 sheet carries an ASTM D2000 M3CA line callout | ASTM; Parker E3609-70 datasheet |
| Aerospace callout | NAS1613, O-ring packing resistant to phosphate-ester fluid; the Parker handbook pairs its ethylene propylene compounds E0515-80 (revision 2) and E1267-80 (revision 5, 75 to 85 Shore A) with it | Parker ORD 5700 Table 8-4 (page 8-5), read 2026-09-24 |
| Compliance available | FDA 21 CFR 177.2600, NSF/ANSI 51 and 61, USP Class VI, KTW, WRAS on specific compounds | Parker E3609-70 datasheet (which states FDA, NSF 51, NSF 61, KTW, WRAS, USP Class VI, USP 87) |
Callouts and listings
EPDM is the material behind most drinking-water and clean-in-place listings and behind the aerospace phosphate-ester seal. A listing belongs to the specific compound, never to the family; ask for the compound number and the listing on any order where it matters.
| Callout | What it covers | Note |
|---|---|---|
| NAS1613 | O-ring packing resistant to phosphate-ester fluid, as the Parker handbook's Table 8-4 titles it | A National Aerospace Standard issued by the Aerospace Industries Association (AIA); the handbook pairs ethylene propylene compounds with revisions 2 and 5. Send the callout and revision as printed. |
| FDA 21 CFR 177.2600 | Rubber articles for repeated use in food contact | "FDA compliant" is the maker's own statement about the compound; see the FDA and food-grade guide |
| NSF/ANSI 61 | Drinking-water system components | The potable-water listing is usually an EPDM |
| NSF/ANSI 51 | Food equipment materials | Commercial food equipment |
| USP Class VI, USP 87, ISO 10993 | Biological reactivity and biocompatibility | Pharmaceutical and medical service; the E3609-70 sheet carries the reports; see the USP Class VI guide |
| KTW, WRAS | German and UK drinking-water schemes | Export water fittings |
| ASTM D2000 line callout | A line callout on the compound's datasheet (M3CA on the E3609-70 sheet) | The datasheet's service range is the rating |
Where EPDM O-rings work, and where they fail
| Medium or condition | Verdict | Note |
|---|---|---|
| Hot water, steam, clean-in-place chemistry | Excellent | Steam-rated grades to 204 C (Parker ORD 5700) |
| Potable water | Excellent | NSF/ANSI 61 listed compounds |
| Glycol brake fluid (DOT 3 and 4) and silicone brake fluid (DOT 5) | Excellent | Brake fluid is butyl or EPDM, never nitrile or FKM |
| Phosphate-ester hydraulic fluid | Excellent | The NAS1613 application |
| Acids, alkalis, ketones, alcohols | Good | Polar media; the E3609-70 sheet lists them as compatible |
| Ozone, sunlight, weather | Excellent | Saturated backbone |
| Silicone oil and grease | Good | The only oils it tolerates; use them for assembly |
| Petroleum oil, grease, fuel, mineral-oil hydraulic fluid | Destroyed | Nitrile or Viton® |
Sizes and forms we supply
Every AS568 size, the general-purpose dash sizes and the boss-seal sizes alike, and the ISO 3601 metric series, in the durometers listed above; O-ring cord for rings spliced and vulcanized by the maker in odd diameters (static service only); and X-rings and backup rings in the same families. The AS568 chart and the AS568 sizes in millimeters carry the dimensions, and the dash number guide explains the numbering.
How EPDM compares with its neighbors
| Material | Parker ORD 5700 range | Where EPDM wins | Where it loses |
|---|---|---|---|
| Nitrile (NBR) | -34 C to 100 C | Water, steam, weather, brake fluid, cold | Any petroleum product |
| FKM (Viton) | -26 C to 204 C | Steam, brake fluid, ketones, cold | Oil, fuel, solvents, dry heat above 150 C |
| Silicone (VMQ) | -54 C to 204 C | Steam, dynamic service, tear strength | Dry heat above 150 C, extreme cold |
| FFKM | -26 C to 320 C; maker grade sheets to 327 C | Cold, availability | Steam with oil present, aggressive chemistry at heat |
Where EPDM fits
Where the medium is water-based, glycol-based or phosphate-ester, or the seal lives outdoors, and petroleum products are guaranteed absent. For oil, the usual fits are nitrile or Viton; the EPDM vs FKM guide draws the water-versus-oil line. For dry heat with no steam, silicone. The same material in sheet form, waterjet-cut to your drawing, is on the EPDM gasket material page, and the chemical compatibility guide covers the media in more detail. A certificate of conformance ships with every order; the cure date is on the label, and the shelf-life guide explains how both are read, and the FAIR guide covers first-article reports where a purchase order asks for one.
Sources: Parker O-Ring Handbook ORD 5700, section 2.2, read 2026-09-14; Parker E3609-70 compound datasheets, read 2026-08-13; ASTM D1418; ASTM D2000; AS568; ISO 3601; Parker O-Ring Handbook ORD 5700, Table 8-4 (NAS1613, page 8-5), read 2026-09-24; hardness guidance (page 2-10), stock O-ring kits (page 3-6) and Table 8-5 compound hardness, read 2026-09-25; 21 CFR 177.2600; NSF/ANSI 51; NSF/ANSI 61; USP Class VI; ISO 10993-5 and -10.
Viton is a trademark of The Chemours Company; Parker is a trademark of Parker Hannifin Corporation. No affiliation or endorsement is implied.
Frequently asked
Can EPDM touch any oil at all?
Silicone oils and greases, yes; the E3609-70 datasheet lists them as compatible. Petroleum and mineral oils, no, in any amount; assemble with a silicone or glycol-based lubricant.
Is every EPDM O-ring safe for drinking water?
No. Only compounds listed to NSF/ANSI 61 or the local scheme are; ask for the compound number and the listing.
Peroxide or sulfur cure?
Peroxide-cured EPDM is the usual choice for steam, hot water and potable-water listings; sulfur-cured compounds are common in general industrial service. The compound sheet states the cure.
Does EPDM work for brake fluid?
Yes, for glycol (DOT 3 and 4) and silicone (DOT 5) fluids; the Parker handbook rule is that brake fluid is butyl or EPDM only, never nitrile or FKM.
What is the aerospace EPDM callout?
NAS1613, the National Aerospace Standard for O-ring packing resistant to phosphate-ester fluid. The Parker handbook pairs ethylene propylene compounds with it: E0515-80 with revision 2 and E1267-80 with revision 5. Send the callout and its revision as printed.
How hot can an EPDM O-ring run in steam?
The Parker range puts steam-rated compounds at 204 C, against 150 C continuous for the family in other media. The compound sheet names whether a grade is steam-rated.
How do I tell an EPDM O-ring from a nitrile one?
Not by looking; both are usually black. A ring that swelled and went gummy in oil was probably EPDM; a ring that cracked outdoors was probably nitrile. The compound number, or an immersion test, is the only reliable identification, which is why every request should name the material.
Does EPDM need a special groove or lubricant?
Standard AS568 sizes and gland dimensions apply. Never assemble EPDM with a petroleum-based grease; use a silicone or glycol-based assembly lubricant. See the groove design guide.
Can EPDM be sterilized repeatedly?
The medical-grade E3609-70 sheet lists resistance to repeated steam, gamma and ethylene-oxide sterilization, with low compression set. It is the same polymer family as the industrial grades; the difference is the tested compound.
Related guides
Orders are handled under Conquest Seal's AS9100D quality management system, whose certificate scope includes distribution.
Send the part number and the quantity for EPDM
The AS568 dash number or the inside diameter and cross-section, the durometer, the quantity, the medium and temperature, and any specification the print names. A Conquest representative replies. Quotes answered within one business day. A person answers (714) 632-9830, Pacific business hours.
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