Enter the code as printed, or the chemical name in English or Russian. A trade name is read too, as the code of its family, where two sources agree on it. Below, an offered material can be checked against it: the code, the hardness and the cure.
No temperature ranges and no chemical compatibility tables here: both depend on the compound, not on the code. Ask for the compound’s datasheet and name the medium and the temperature in the request.
On the code and hardness alone: the compound, the medium and the temperature decide.
An O-ring bag, a seal drawing or a datasheet names the rubber by its ISO 1629 or ASTM D1418 code: NBR, FKM, EPDM, VMQ, often with the hardness in Shore A, as in FKM 75. Enter the code or the name and the reader gives the full chemical name, the group set by the last letter and the other spelling of the same family where one is in use, checks an offered material against the one wanted and writes an RFQ line.
This is a reference for reading a code and writing an RFQ, not a material selection. The temperature range and the chemical resistance depend on the compound, not on the code, so they are not given here: the compound’s datasheet, the medium and the temperature decide.
The letters name the chemistry of the polymer: NBR acrylonitrile-butadiene rubber, EPDM ethylene-propylene-diene rubber, FKM fluorocarbon rubber, VMQ methyl vinyl silicone rubber. Some families have a second spelling in use: FPM beside FKM, FFPM beside FFKM, MVQ beside VMQ. FEPM is a material of its own, not a spelling of FPM.
The last letter is the group, set by the main chain of the polymer: M a saturated carbon chain, R an unsaturated one, O oxygen in the main chain, Q silicon and oxygen (the silicones), U carbon, oxygen and nitrogen (the urethanes). The group explains the code; it does not replace the data of the compound.
A number beside the code is read here as the Shore A hardness and repeated as typed, with nothing drawn from it; check it against the bag or the drawing. One code covers many compounds, with different fillers and a different cure (sulphur or peroxide), so the temperature and the resistance to a medium are read from the compound’s datasheet.
| Code | Group | Name | Other spelling |
|---|---|---|---|
| NBR | R | acrylonitrile-butadiene rubber (nitrile rubber) | — |
| HNBR | R | hydrogenated acrylonitrile-butadiene rubber (hydrogenated nitrile) | — |
| XNBR | R | carboxylated acrylonitrile-butadiene rubber (carboxylated nitrile) | — |
| FKM | M | fluorocarbon rubber (fluoroelastomer) | FPM |
| FFKM | M | perfluoroelastomer | FFPM |
| FEPM | M | tetrafluoroethylene-propylene rubber | — |
| EPDM | M | ethylene-propylene-diene rubber | — |
| EPM | M | ethylene-propylene rubber (copolymer, without the diene) | — |
| VMQ | Q | methyl vinyl silicone rubber | MVQ |
| FVMQ | Q | fluorosilicone rubber | — |
| CR | R | chloroprene rubber (polychloroprene) | — |
| ACM | M | polyacrylate rubber (acrylate rubber) | — |
| AEM | M | ethylene acrylate rubber (ethylene acrylic) | — |
| AU | U | polyester urethane rubber | — |
| EU | U | polyether urethane rubber | — |
| IIR | R | isobutene-isoprene rubber (butyl rubber) | — |
| NR | R | natural rubber | — |
| SBR | R | styrene-butadiene rubber | — |
| CSM | M | chlorosulfonated polyethylene | — |
| ECO | O | epichlorohydrin rubber, copolymer with ethylene oxide | — |
| CO | O | epichlorohydrin rubber, homopolymer | — |
Every code, group and name is confirmed by two independent sources. Left out because the sources differ or only one gives it: which standard or edition prints FPM, FFPM and MVQ; the code FMQ (one source treats it as another spelling of FVMQ, another a code of its own); how CR and VMQ stand up to mineral oils; whether VMQ suits moving seals; notes on NR; every temperature range and every chemical resistance rating, which depend on the compound.
The ASTM D1418 abstract with its classes and codes; a US seal maker’s O-ring handbook (its table of groups and codes, its abbreviations and its section on each elastomer); a US O-ring maker’s elastomer chart; a European seal distributor’s technical O-ring handbook (its chapter on the basic elastomers); a US seal supplier’s list of abbreviations; an Austrian seal maker’s note on the fluoroelastomer abbreviations; the Wikipedia articles on FKM, FFKM and chlorosulfonated polyethylene; a German company’s glossary entry on perfluoroelastomer; the specification SAE AMS7264B for methyl vinyl silicone rubber. Every value is in at least two of them.
Yes: both name the same family, fluorocarbon rubber. The sources differ on which standard, or which edition, prints FPM, so this page does not say. FEPM is a different material, a copolymer of tetrafluoroethylene and propylene, and not another spelling of FPM.
It is the group, set by the main chain of the polymer: M a saturated carbon chain, R an unsaturated carbon chain, O oxygen in the main chain, Q silicon and oxygen (the silicones), U carbon, oxygen and nitrogen (the urethanes). So EPDM and FKM are M rubbers, while NBR and CR are R rubbers.
Both depend on the compound, not on the code: two FKM compounds from two makers can differ in both. The family notes on this page are only the general points two independent references agree on. Ask for the compound’s datasheet, and name the medium and the temperature in the request.
The code as printed and the hardness in Shore A; the colour; the medium and the temperature at the seal; any certificate needed, for example for food, drinking water or fire; the size or the part number; the quantity; and a photograph of the bag or the drawing.
A reading is a check of the code, not a material selection. Name the medium, the temperature and any certificate needed, and Vessel Core checks them before an offer goes back.
