FKM 4 - Fluoroelastomer terpolymer of tetrafluoroethylene, propylene & vinylidene fluoride
| Clwyd reference | FKM 4 |
| ASTM classification | FKM 4 |
Terpolymer of tetrafluoroethylene (TFE), propylene (P) and vinylidene fluoride (VF2/VDF). While base resistance is increased in type 4 FKMs, their swelling properties especially in hydrocarbons are worsened. Typically they have a fluorine content of about 67 weight percent. | |
| Typical applications | |
| Advantages | |
| Disadvantages | |
| Available hardness range (Shore A) | 60 - 95 |
| Upper continuous service temp. | 250°C |
| Min. temp. for sealing applications | -5°C |
| Minimum non-brittle temp. | -10°C |
| Tensile strength (up to) | 20 MPa |
| Elongation at break (up to) | 250% |
| Price Bracket | Medium |
| ASTM 1 Oil | Excellent |
| ASTM 2 Oil | Excellent |
| ASTM 3 Oil | Excellent |
| Kerosene | Excellent |
| Liquid B | Excellent |
| Liquid 101 | Excellent |
| Phosphate ester | None |
| Ketone | None |
| Toluene | Excellent |
| Iso-octane | Excellent |
| Methanol | Excellent |
| Acid (weak) | Excellent |
| Acid (strong) | Excellent |
| Base (weak) | None |
| Base (strong) | None |
| Hydrogen sulphide | None |
| Steam | None |
| Ozone | Excellent |
| Radiation | Excellent |