Specification guide
FDA and Food-Grade O-Rings: What Qualifies
What FDA compliant means for an O-ring compound (21 CFR 177.2600), how NSF, USP Class VI, ISO 10993 and 3-A differ, which materials are offered, and what the RFQ must state.
An FDA compliant O-ring is molded from a compound whose ingredients are on the allow-list in FDA regulation 21 CFR 177.2600 (rubber articles intended for repeated use in contact with food) and that meets the regulation's extraction limits. Compliance is self-certified by the compound maker against that regulation; the FDA does not approve compounds or parts, so the correct phrase is "FDA compliant", and a part described as "FDA approved" is mislabeled. Food, beverage, dairy and pharmaceutical equipment commonly specifies one of several things, and they are not interchangeable: 21 CFR 177.2600, an NSF/ANSI 51 or 61 listing, USP Class VI, ISO 10993 biocompatibility, or a 3-A Sanitary Standard for the equipment. This guide explains what each one covers, which O-ring materials are offered against them, and what an RFQ needs to say.
What is the difference between FDA, NSF, USP Class VI and 3-A?
Each requirement is issued by a different body, tests a different thing and is documented in a different way. The summary below follows the Parker® O-Ring Handbook (ORD 5700) and the Parker E3609-70 compound datasheets.
| Requirement | Issued by | What it covers | How it is documented | Typical use |
|---|---|---|---|---|
| FDA 21 CFR 177.2600 | US Food and Drug Administration (a regulation, not a certificate) | Ingredient allow-list plus extraction limits for repeated-use rubber articles in food contact | Self-certified by the compound maker; a certificate of compliance names the compound | Food processing and packaging equipment |
| NSF/ANSI 51 | NSF, a third-party listing body | Food equipment materials | NSF listing of the compound or product | Commercial food equipment |
| NSF/ANSI 61 | NSF | Drinking water system components, including extractables into potable water | NSF listing | Potable water; usually EPDM |
| USP Class VI | United States Pharmacopeia chapter 88 | Biological reactivity of the material in vivo (implantation and systemic tests) | Test laboratory report against USP 88; USP 87 is the in vitro cytotoxicity chapter | Medical devices and pharmaceutical processing |
| ISO 10993-5 and -10 | ISO | Cytotoxicity (-5) and sensitization and irritation (-10) of a device material | Test report per part | Medical devices; often paired with USP Class VI |
| 3-A Sanitary Standards | 3-A SSI | Hygienic design and materials of dairy and food equipment; elastomers are covered by their own 3-A standard | Equipment authorization; the seal material must meet the elastomer standard | Dairy and food plants |
| EC 1935/2004 | European Union | The EU framework for materials in contact with food | Declaration of compliance | Equipment sold into the EU |
| KTW and WRAS | German and UK drinking-water schemes | Materials in contact with drinking water | Scheme approval of the compound | Water fittings for those markets |
One compound can carry several of these at once. Parker's EPDM compound E3609-70, per its datasheet, is listed as FDA compliant and to NSF 51, NSF 61, KTW, WRAS, USP Class VI and USP 87, with a separate ISO 10993-5 and -10 test report; its rated range on that sheet is -57 C to 150 C (-70 F to 302 F) continuous. Its sheets list hot water, steam and cleaning agents among the media it resists. It is not compatible with mineral oils, greases or fuels, like every EPDM.
Which O-ring materials are offered FDA compliant?
Compliance belongs to the specific compound, not to the polymer family, so every material below exists in both compliant and non-compliant compounds; the compound number on the certificate is what matters. Color alone proves nothing: a white ring is not compliant because it is white. Temperature ranges are the Parker O-Ring Handbook figures for the polymer family; the compliant compound's own sheet governs.
| Material | Continuous range (Parker handbook) | Where it is the usual choice | Watch out for |
|---|---|---|---|
| Silicone (VMQ) | -54 C to 204 C (-65 F to 400 F) | The default for food and beverage contact; dry heat, ovens, extreme cold; platinum-cured grades for USP Class VI | Static service only; fuels and steam |
| EPDM | -57 C to 150 C (-70 F to 302 F); steam compounds to 204 C | Hot water, steam, clean-in-place chemistry, potable water (NSF 61) | Never petroleum oils, greases or fuels |
| Viton® (FKM) | -26 C to 204 C (-15 F to 400 F) | Fats, oils and higher temperatures; fryer and oil-contact lines | Steam, hot water, ketones, amines |
| Nitrile (Buna-N) | -34 C to 100 C (-29 F to 212 F) | Oil-contact food machinery at moderate temperature | Ozone, sunlight, ketones, low heat ceiling |
| FFKM | -26 C to 320 C (-15 F to 608 F) | Aggressive cleaning chemistry meeting high temperature; pharmaceutical grades with USP Class VI reports | Cost; fluorinated refrigerants |
| PTFE-encapsulated | No single range applies to an encapsulated ring; the jacket and core sheets govern. | Inert static flange seals where nothing may leach | Static or slow service only; no elastic memory |
The silicone and EPDM guides cover two common food-contact choices; the Viton guide covers oil and fat service.
How do I read a compliant compound's datasheet?
A compound sheet carries three things worth checking before the certificate. First, the compliance line itself: it should name the regulation or listing (21 CFR 177.2600, NSF/ANSI 51, USP Class VI) and the compound number, not just say "food grade". Second, the ASTM D2000 line callout, which is the compound's engineering shorthand: the E3609-70 sheet, for example, reads M3CA 710 A25 EA14 F18 with Z suffixes. Read left to right per ASTM D2000: M means SI units, 3 is the grade, C is the type (70-hour heat aging at 125 C), A is the class (no oil-resistance requirement, which is the loosest cell in the table and exactly right for an EPDM), 710 means 70 Shore A and 10 MPa minimum tensile, and the suffix groups name the tests the compound passed: A heat resistance, EA aqueous fluid resistance, F low-temperature resistance, Z requirements the user specifies. Third, the temperature range and the media list, which govern regardless of compliance.
A compound can be FDA compliant and still be the wrong material for the line; compliance says what may leach, not what the seal survives.
What should the RFQ state?
| Item | Why it matters | Example |
|---|---|---|
| Size | We stock every AS568 size; the compound is confirmed on the quote | AS568-214, or 24.99 x 3.53 mm (AS568 chart) |
| Material family | Compliance exists in every family; the media picks the family | EPDM for steam and clean-in-place; silicone for dry contact |
| The exact requirement | FDA, NSF 51, NSF 61, USP Class VI and 3-A are different documents | "21 CFR 177.2600 compliant, certificate of compliance with shipment" |
| Documentation needed | A certificate names the compound; a USP report is a lab document | "CoC naming the compound number" |
| Temperature and cleaning chemistry | The compound sheet's range and media list govern | "CIP with caustic at 80 C, steam sterilization weekly" |
| Color, if it matters | Detectable and color-coded compounds exist for line inspection | "White or blue preferred" |
| Static or dynamic | Silicone is static only; dynamic food service usually means EPDM or FKM | "Static face seal on a fitting" |
Material choice then follows the temperature range guide and the chemical compatibility guide.
Viton is a trademark of The Chemours Company; 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, read 2026-09-14
- Parker compound E3609-70 datasheet (FDA), read 2026-08-13
- Parker ethylene propylene 70 durometer O-ring datasheet (drinking water and medical), read 2026-08-13
- Parker E3609-70 ISO 10993-5 and -10 compliant EPDM seal material sheet, read 2026-08-13
- 21 CFR 177.2600
- 3-A Sanitary
- AS568
- ASTM D2000
- EC 1935/2004
- ISO 10993
- ISO 10993-5
- NSF/ANSI 51
- NSF/ANSI 61
- USP 87
- USP 88
- USP Class VI
Reviewed by Grant Midstokke, Conquest Seal Corporation. Last updated September 2026. Spec values in this guide are drawn from the sources named in the sentence where each appears; the compound datasheet and your application conditions govern the final choice.
Frequently asked questions
Is there such a thing as an FDA approved O-ring?
No. The FDA publishes the regulation; compound makers self-certify against it. "FDA compliant" is the accurate phrase, and the certificate should name the compound.
Is a white silicone O-ring automatically food grade?
No. Color is a pigment choice. The compound number on the datasheet and its compliance line are the only evidence.
Do I need USP Class VI for food equipment?
Usually not. USP Class VI is a biological reactivity standard used for medical and pharmaceutical applications. Food equipment normally specifies 21 CFR 177.2600, NSF/ANSI 51 or 3-A.
Which material for a steam-in-place line?
A steam-rated EPDM compound with the relevant compliance, or an FFKM steam grade where the line also sees oils or aggressive solvents. The EPDM vs FKM comparison explains why FKM is the wrong choice for steam.
Can the same compound be FDA compliant and NSF 61 listed?
Yes. The Parker E3609-70 datasheet lists both, along with NSF 51, USP Class VI, KTW and WRAS. One compound can satisfy several schemes; each still has to be named on the paperwork.
Which EPDM grade covers both drinking water and steam sterilization?
Parker's E3609-70 ethylene propylene datasheets describe a 70 Shore A compound rated from -57 C to 150 C continuous, with hot water and steam service to 149 C. It lists repeated steam, gamma and ethylene oxide sterilization among the exposures it resists, and mineral oils, greases and fuels as the one family it cannot touch. Ask for the datasheet with the quote so the listing named on the print is the one the compound actually carries.
Does a food-contact compound change the O-ring size or groove?
No. A food-contact compound is an ordinary elastomer with a restricted ingredient list, so it is molded to the same AS568 or ISO 3601 sizes and takes the same gland as any other ring of that family. What can change is hardness and compression set, because the pigment and filler choices are narrower, so read the compound datasheet rather than assuming the family default.
How do I read the D2000 callout on a food-grade EPDM datasheet?
The Parker E3609-70 sheet carries the line callout M3CA 710 A25 EA14 F18 with Z suffixes: M is SI units, 3 the grade, C the 125 C heat-aging test, A the no-requirement oil class (right for a material never meant to see oil), 7 is 70 Shore A and 10 a 10 MPa minimum tensile. The Z suffixes are special requirements written out on the datasheet rather than in the standard. The type letter is a 70-hour aging temperature, not a service rating.
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