Tetrafluoroethylene full name PTFE or PTFE, Teflon, etc., hereinafter referred to as tetrafluoroethane.
In 1969, tetrafluoride expanded into a high toughness and porosity, low density material, known as expanded polytetrafluoroethylene, and applied on seals. Expanded PTFE not only retains the unique properties of PTFE, that is, chemical stability, low coefficient of friction, anti-aging, etc., but also to expand the scope of temperature. Improve the mechanical strength, and has some new features (porous, breathable, hydrophobic and high toughness, etc.).
At present the industry is also a large number of use of expanded graphite and asbestos as a sealing material, but they are some problems. Expanded graphite due to low strength and lack of application theory guidance, its application effects and scope has been limited. Asbestos products not only with the temperature rise, the crystallization of water will gradually precipitate, fiber strength will be reduced, and asbestos in the capillary fibers inhalation after the respiratory system is very harmful to the human body. Some industrialized countries have already begun to restrict the use of asbestos products, proposed to find asbestos substitutes of the plan. Expanded PTFE tape is an ideal new type of sealing material. The main performance of the expanded PTFE tape is: density 0.2 ~ 0.3g / cm-3; thermal conductivity of 0.17kcal / m * h, (0 ℃): temperature range of -268 ~ 315 ℃; pressure range 211kgf / cm2 (higher than the pressure can be consulted to the manufacturer); natural temperature of 504 ± 38 ℃; friction coefficient of 0.2; matrix tensile strength of 527kgf / cm2; elastic modulus of 3515kg / cm2. (At 73 ° C): Chemical adaptability is inert to fluorine and alkaline metals.
According to information, expansion of PTFE seal products currently have three new products, namely, flange sealing tape (on behalf of the gasket), stem packing and GFO fiber pump packing.
Tetrafluoro Flange Seal Tape is a white opaque solid ribbon with high toughness and softness. In this belt is attached to a sticky tape, so called sealing tape. It is flexible, compressible, high tensile strength, that is, do not pollute the media, nor by the erosion of the media, excellent chemical stability, in a wide temperature range of long-term use without deterioration.
Stem packing is made of expanded PTFE film, it also has a good performance of PTFE flange tape, and the friction coefficient is small, suitable for the temperature of -268 ~ 288 ℃, easy to install, the wear of the stem But also to achieve a good seal.