Polytetrafluoroethylene (PTFE, Teflon®)
|Teflon®||DuPont Dow Elastomers|
|ASTM D1418 Designation:||FEP|
PTFE is the most chemically inert of the O-ring materials, it is a tough polymer possessing an incredible working temperature range.
Seals for wide chemical exposure situations, with special emphasis on temperature extremes. Its outstanding tear resistance and abrasive resistance result in its slippery surface properties that make it advantageous for use in seals in moving systems such as mass spectrometer probes and valves.
|Standard Compound:||-185° (-300°F) to 232°C (450°F)|
|Hardness (Shore A):||98|
PTFE is resistant to most chemicals including acids, bases, oils, steam and other chemicals. It is also very tough and abrasive resistant, even at elevated temperatures. Seals fabricated from this material feature outstanding weather resistance, high resistance to ozone, and high resistance to the degrading effects of exposure to such solvents as acetone, MEK, and xylene. Possessing average elastomer characteristics of 2,500 to 3,500 psi tensile strength, and 300% elongation, they are tough, impact resistant, low friction, non-twisting performers over an extremely wide temperature range.
PTFE is hampered by very poor elastic memory at room, or low temperatures. This presents problems in O-ring installation, requiring extra care to be taken in control over O-ring I.D.
Stretch. Heating PTFE in boiling water, or in a controlled oven, to 200°F is said to enable an O-ring stretch of 10 to 20% to be achieved, thereby assisting installation, and helping to assure a tight fit. Because of its poor tear resistance, during O-ring installation particular care should be taken to avoid nicking or scratching Teflon®, as imperfections will cause O-ring leakage. However the material is not easily compressed, and therefore may not seal as easily as some of the other polymers. Finally, the tendency of virgin Teflon® to cold flow over time, when used in gasket type applications, may require special material compounding (with fillers) to control such “creep” in critical sealing situations.
Please note: This Material Data Sheet section is to be used as a professional guide only. Eastern Seals (UK) Ltd may source their products from a variety of Quality Approved Suppliers and the data shown should not be relied upon by any purchaser without verification of material source.
|PTFE||BLACK||-100⁰C to +250⁰C||–||A Conductive PTFE compound 1% by weight composition of Carbon Black. 99% free flowing granular PTFE, for auto Isostatic and general purpose compression moulding. Material meets the FDA regulation under code 21CFR 177.1550 and Euro Directive 10/2011/EC for material that may come into contact with food.|
|PTFE FDA (mouldings)||WHITE||-250⁰C to +250⁰C||–||This Virgin PTFE is a high bulk agglomerated grade designed for general, automatic and Isostatic moulding. It is particularly suitable for producing large mouldings from relatively compact tools. Material meets the FDA regulation under code 21CFR 177.1550 and Euro Directive 10/2011/EC for material that may come into contact with food.|
|PTFE FDA / WRAS (rods)||BLACK||-250⁰C to +250⁰C||–||A Virgin PTFE produced in tube or rod form which conforms to the requirements of BS EN ISO 13000-1: Grade 2. Material meets the FDA regulation under code 21CFR 177.1550 and Euro|
Directive 10/2011/EC for material that may come into contact with food, and Water Regulations Advisory Scheme to BS6920.
|PTFE FDA / WRAS||WHITE||-250⁰C to +250⁰C||–||A Virgin PTFE free flow granular resin used in a multi-purpose role with an excellent combination of handleability, processability, machinability and end use properties. Meets the FDA regulation under code 21CFR 177.1550 and EU Directive 10/2011/EC for material that may come into contact with food. Also meets WRAS Approval. Conforms to the requirements of BS EN ISO 13000-1 Grade 1 Type P (as processed) or Type S (Stabilised) and to ASTM D 4894 type IV grade 2. High and low working temperature and low friction.|