Over the decades, polyvinyl chloride (PVC) valves have penetrated both commercial and domestic domains. PVC valves made with suitable additives provide the desired physical and chemical compatibility. Although they have limited use in high temperature applications, advances in PVC technology have enabled manufacturing of the valves with reasonable tolerance to medium range temperatures. In a similarity with their metal counterparts, plastic valves are machined using similar CNC machining centers and lathes, however the parts of the PVC valves are joined using threaded joints or cement or fastened using fasteners. They can be installed with very little additional help from wrenches.
Purpose of PVC valves:
One of the most common reasons for the failure of conventional metal-based valves is corrosion. Corrosion affects industries such as chemical processing, nuclear power generation, onshore and offshore oil and gas, underground pipeline, water treatment, sewage handling and treatment, highway maintenance, aviation, and metalwork. Moreover, options for a corrective action or a preventive action are limited. Pervasive nature of corrosion in certain industries made them look for alternative options such as PVC valves as they were virtually unaffected by corrosive atmosphere. Furthermore, smooth surfaces are resistant to scaling and allow better flow rates, while external surfaces require no additional coating to protect the shell from environmental damage. PVC valve avert any organic growth, making it suitable for ultra-pure applications such as semiconductor fabrication and manufacturing of polymers. Servicing of the plastic valves is relatively easier since no special tools or tackles are required to disassemble the valves and allows on-site servicing requiring minimal downtime. These features made it desirable in some industries.
Features of PVC valves:
As discussed earlier, PVC valves offer non-corrosive, non-contaminating, and smooth surface for process fluids. Apart from these properties, they are lighter in weight than metal valves of similar sizes. The PVC valves offer resistance to acid along with corrosion and they repel any formation of scale on the surface because of their smoothness. In comparison with metal valves, integration with plastic pipes and fixtures are easier with PVC valves. According to the life cycle assessment of PVC commissioned by the European Commission, the average lifecycle of PVC water pipes range anywhere between 40 and 80 years and thereby a conservative estimate of the PVC valves’ life cycle is close to 10-20 years. This compares favorably to other alternatives because of their use of lesser non-renewable resources i.e. 57% of PVC is derived from salt and the remaining 43% is obtained from oil/gas. Most of the PVC valves can handle pressure of up to 150 lbs./sq.in, which is lower for most piping sizes in the schedule 80 threaded piping system. Due to presence of more than fifty percent chlorine in the PVC, PVC valves are fire-resistant. Even when the valves are burned, they emit hydrogen chloride gas that prevents oxygen from reaching the surface and thereby prevents faster reaction. The valves offer excellent chemical compatibility with salts, alkalis, oxidizing agents, and acids. In addition, they offer reasonable compatibility with organic solvents. Since PVC has easy processing characteristics, the desired specification for the valves can be achieved. PVC valves are relatively more cost effective than metal valves due low weight and lower price of base material. These valves are also highly resistant to ultra violet rays, which makes them suitable for UV sensitive applications such as photographic material. Their no-reaction characteristic with most organic and non-organic material makes them suitable for handling medical and bodily fluids.
Conclusion:
The PVC valves have penetrated both the domestic and commercial market due to their performance characteristics and advantages they offer over the valves made out of other materials.
For more information about PVC valves and other related products, please feel free to contact Golden Highope Industrial INC. LTD.
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