Plastic pipe polyvinylchloride

For process water, steel pipes are used unless iron pickup is to be minimized. Plastic pipes (polyethylene and polyvinylchloride) are used but they sometimes need external protection from solvents present in industrial atmospheres, ultraviolet radiation (including sunlight), freezing and mechanical damage. 

Although they have an endless variety of properties, polymers can be divided into three general categories, based on their form and resistance to stretching. These are plastics, fibers, and elastomers. Plastics differ in form from fibers whereas plastics exist as blocks or sheets, fibers have been drawn into long threads. Unlike plastics or fibers, elastomers can be stretched without breaking. Polyethylene packaging films and polyvinylchloride (PVC) pipe are examples of plastics. Orion carpets are made from polymer fibers, and mbber bands are elastomers. Some polymers, such as Nylon, can be formed into both plastics and fibers. 

Another important addition polymer is polyvinylchloride (PVC), which is tough and easily molded. Floor tiles, shower curtains, and pipes are most often made of PVC, shown in Figure 12.30. The addition polymer polyvinylidene chloride (trade name Saran), shown in Figure 12.31, is used as plastic wrap for food. The large chlorine atoms in this polymer help it stick to surfaces such as glass by dipole—induced dipole attractions, as we saw in Section 7.1. 

Vinyl chloride is consumed in large quantities as a raw material to manufacture pipe, hose, wrapping, and other products fabricated from polyvinylchloride plastic. This highly flammable, volatile, sweet-smelling gas is a known human carcinogen. 

Polyvinylchloride (PVC) is a hard, amorphous polymer which softens at about 85 °C. Also in PVC rubbers are sometimes added in order to improve the impact strength. The main applications of PVC are pipes, gutters, front panels of buildings, cables, bottles, floor tiles. A much softer and more flexible material is obtained by blending with plasticizers soft or plasticized PVC is being used in artificial leather, tubes and hoses, footwear, films, etc. 

Shims Shims are used to prevent modules from moving back and forth during pressurization and depressurization. Such movement could wear on the internal O-ring seals. Shims are plastic spacer rings similar to washers. They are typically 0.20-inches thick, and can be purchased from the manufacturer of the pressure vessel or fashioned from polyvinylchloride (PVC) pipe. Shims fashioned from PVC pipe must be cut parallel and free of burrs to work correctly. They are installed between the face of the lead membrane module and the adapter hub (see Figure 6.16) after all the... 

The major use of vinyl chloride (also known as vinyl chloride monomer, VCM) is in the production of the ubiquitous plastic, PVC or polyvinylchloride, which began to be used in the 1940s. This polymer is used in a wide variety of products ranging from cling film, bottles, car components, pipes, electrical insulation, and window frames. Unfortunately, vinyl chloride, which is used to make the plastic, is a hazardous chemical. For this reason and because PVC is an organochlorine compound, it has received a bad press. It has important properties, however, such as flexibility, toughness, and durability, that make it an extremely useful and versatile material. 

For encapsulation cups, the present writer has occasionally used 20 to 25 mm-tall cylinders made from sections of a copper or brass pipe and some of the relatively heat-resistant polyvinylchloride plastics, both reusable. The interiors of these containers are coated with silicone stopcock grease as a bond breaker. A glass microscope slide, also coated with silicone stopcockgrease, supports the cylinder and the pair are placed on the slide warmer or hot plate the epoxy resin is introduced as described above. 

An important example of a polymer is that of polyvinylchloride, shown in Figure 9.15. This polymer is synthesized in large quantities for the manufacture of water and sewer pipe, water-repellant liners, and other plastic materials. Other major polymers include polyethylene (plastic bags and milk cartons), polypropylene (impact-resistant plastics and indoor-outdoor carpeting), polyacrylonitrile (Orion and carpets), polystyrene (foam insulation), and polytetrafluoroethylene (Teflon coatings and bearings) the monomers from which these substances are made are shown in Figure 9.16. 

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