PFA Lined Introduction
BUENO's PFA lined valves are resistant against corrosion and guarantee zero leakage. They are widely accepted in semiconductor, microelectronics, pharmaceutical, food and beverage, petrochemical, refining, biochemical, cosmetics and high purity water industries.
►Features of PFA liner
For a number of
years, fluoropolymers have played a significant role in the chemical and
similar industries, protecting plants and equipment against a wide range
of corrosive media. This is due to PFA having substantially better
chemical resistance and thermal stability than other engineering
plastics. PFA, a perfluoro-alkoxy polymer which has been in successful use
for 20 years as a lining material, is now a thermoplastic successor to
PTFE. Compare to PTFE, PFA has the equivalent thermal and chemical
resistance while superior in processability, translucency, permeation
resistance and mechanical strength.
In the chemical industry, PFA is more applied to linings than PTFE because using PTFE is more difficult for the lining of metal parts of complicated shape, such as valves and pumps. PFA material, a thermoplastic material with a well-defined melting point, can be processed through transfer molding to achieve better lining quality.
The granular material is melted in a melt pot and then forced into the hot tool. This transfer molding method makes very precise wall-thicknesses, even at tight radii and in undercuts. In addition, no mechanical finishing is needed, except the removal of spruce and the smoothing of mating faces of flanges. Lastly, the evenness of wall-thickness may vary, especially in the case of a more complicated shape such as valve housings.
►Absorption and Permeation
Different from metals, thermoplastics absorb varying amounts of the media which they come in contact. Absorption may be followed by permeation through the liner. Such problems can be solved by increasing the lining's wall-thickness or installing devices to remove the space between fluoropolymer liner and inner metal wall. It is clear that in terms of resistance against permeation and absorption, PFA, or melt-processed fluoropolymers, is better than PTFE.
1. Highly corrosive non-acidifying
acids, such as chloride, sulfuric acid, wet halogen gases, phosphoric acid,
acetic acid, and fluoric acid.
2. Fluid transportation systems where there’s interaction between acids and alkalis.
3. Semiconductor and pharmaceutical manufacturing process where organic compound precipitation and metal ion leaching take place.
►What is a Transfer Molding Liner?
Transfer molding is a type of molding method that evolved from compression molding; It includes heating and cross linking process which are conducted in two separate locations. Transfer molding begins by melting the plastic material as PFA (Polyfluoroalkoxy / fluoroplymers) in the separation chamber, then injects the material into another sealed mold for it to take shape and harden. When the component being shaped has a complex shape or insert(s), the use of compression molding may damage the component or shift the insert(s). Those possible difficulties can be avoided by choosing transfer molding over compression molding. The equipment of transfer molding can be separated into two categories: pot transfer and plunger molding.
►Features of Transfer Molding PFA Liner
- The firm PFA liner is produced by a combination of transfer molding and a special variation of injection molding. This processing method prevents pinholes, cracks, swelling, degradation, and ablation. The Dovetail design enables PFA liner to firmly attach to the valve body, preventing possible peeling, distortion, and shifting.
- Double sealing valve body design. Protection provided by soft sealing and metal sealing prevents leakage caused by aging and degradation of the PFA liner. The metal sealing also provides reinforcement to the metal structure and corrects flange distance orientation.
- Excellent chemical resistance. The entire internal surface of the valve is covered by 2.5mm to 3mm thick PFA liner, which prevents corrosion and permeation from chemicals, solvents, and other acids or alkali.
- Anti-blowout stem with a mark that helps the user to identify the current state of the valve. The valve is open when the mark is parallel with the valve, closed when they’re perpendicular to each other.
- Due to low friction of the PFA material, our PFA lined valves have low torque and are easy to operate.
- BUENO PFA lined valves are manufactured by PFA Perfluoroalkoxy material with FDA certifications; They are safe to be used in food, winery, pharmaceutical, biochemical, semiconductor, and optoelectronic manufacturing industries.
- All of our PFA lined products are water-free and oil-free. The quantity of oil contained is controlled under 1.0mg/sq ft. Higher levels of product purity can also be accomplished upon request.
- Helium leakage tests for BUENO's PFA lined products are conducted according to MSS SP82 standards; the leakage requirements are MAX 6.4*10-4ml/sec.