Application: PTFE and FKM, as two critical sealing materials, are widely used in petrochemicals, pharmaceutical chemicals, new energy, aerospace, and other industries.
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Differences
1. PTFE: The core material of PTFE is polytetrafluoroethylene. The inherent properties of PTFE determine its key advantages: resistance to strong acids (sulfuric acid, nitric acid, hydrofluoric acid), strong alkalis (sodium hydroxide, potassium hydroxide), slight corrosion only under high temperature and pressure when exposed to alkali metals (sodium, potassium) and fluorine.
2. FKM: The core material of FKM is a copolymer of polyvinylidene fluoride (PVDF) and hexafluoropropylene (HFP). The primary advantage of FKM lies in its “elastic sealing capability”: tensile elongation at break can reach 200%–500%, and compression set is only 10%–20%, significantly outperforming PTFE. In terms of temperature adaptability, FKM has a long-term service temperature range of -20°C to 200°C. However, its corrosion resistance is slightly inferior to that of PTFE.
Selection Guide
1. Prioritize PTFE valve seats :
①The medium is highly corrosive.
②Long-term operating temperatures are ≤ -30°C or > 200°C, with frequent and significant temperature fluctuations.
③In ultra-high-pressure conditions: working pressure > 10 MPa, and the medium is corrosive.
2. Prioritize FKM valve seats:
①The medium is non-corrosive or weakly corrosive.
②Moderate temperatures and elastic sealing are required: frequent valve cycling (e.g., globe valves, solenoid valves) or significant pressure fluctuations (e.g., hydraulic systems) necessitate compensation for sealing surface gaps.
Modification/Formulation Adaptation
1. For PTFE-based seals, select fillers according to requirements (carbon fiber for high pressure, graphite for wear resistance, bronze powder for high temperatures). For FKM/FPM seals, select types based on temperature (grades with low HFP content for low temperatures, FFKM for high temperatures and strong corrosion).
2. Economic Balance: For standard conditions (low pressure, non-corrosive), choose pure PTFE seals or standard FKM for lower cost. For critical equipment (where downtime is costly), opt for modified PTFE seals or FFKM, as extending service life is more economical.
3. Material selection must focus on the actual operating conditions, balancing temperature, medium, pressure requirements, and cost-effectiveness, while avoiding blind pursuit of a single performance indicator.
Post time: Dec-31-2025