Difference between revisions of "Plastic Valves"

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Plastic Valves (view source)

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[[Category:Valves]]{{Knoppen}}
[[Category:Valves]]{{Knoppen}}
[[File:Plastic valves.gif|thumb|right|Plastic Valves]]
[[File:Plastic valves1.jpg|thumb|right|Plastic Valves]]
'''Plastic Valves''' are made from plastic materials and are used in applications that require corrosion resistance and/or chemical handling. They are made from acetal polymers, polyvinyl chloride (PVC), chlorinated PVC (CPVC), polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride (PVDF). Acetal polymers offer excellent lubricity, fatigue resistance, and chemical resistance. PVC provides good flexibility, smooth surfaces, and nontoxic qualities. CPVC is suitable for high temperature applications and is used in hot water distribution. PTFE exhibits a high degree of chemical resistance and a low coefficient of friction. PE is a soft, flexible and tough plastic with outstanding electrical properties but poor temperature resistance. It is prone to stress cracking and has poor resistance to ultraviolet (UV) light. PP is similar to PVC, but can be used in exposed applications because of its resistance to UV, weathering and ozone. PVDF has good wear resistance and excellent chemical resistance, but does not perform well at elevated temperatures.




Plastic valves are made from plastic materials and are used in applications that require corrosion resistance and/or chemical handling. They are made from acetal polymers, polyvinyl chloride (PVC), chlorinated PVC (CPVC), polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride (PVDF). Acetal polymers offer excellent lubricity, fatigue resistance, and chemical resistance. PVC provides good flexibility, smooth surfaces, and nontoxic qualities. CPVC is suitable for high temperature applications and is used in hot water distribution. PTFE exhibits a high degree of chemical resistance and a low coefficient of friction. PE is a soft, flexible and tough plastic with outstanding electrical properties but poor temperature resistance. It is prone to stress cracking and has poor resistance to ultraviolet (UV) light. PP is similar to PVC, but can be used in exposed applications because of its resistance to UV, weathering and ozone. PVDF has good wear resistance and excellent chemical resistance, but does not perform well at elevated temperatures.




==Types of Plastic Valves==
==Types of Plastic Valves==
There are many types of plastic valves. [[Ball Valves]] provide tight shut-offs, but are not suitable for sanitary applications. [[Butterfly Valves]] permit flow in only one direction. [[Check Valves]] are self-actuating and prevent the reversal of process flow. [[Diaphragm Valves]] separate the flow of gases from the closure element. Directional valves steer flow through selected passages. [[Diverter Valves]] redirect process flow. Drain valves reduce surplus media. Float valves open or close automatically as the level of a fluid changes. Foot valves are check valves with a built-in strainer. [[Gate Valves]] or knife valves are linear motion valves in which a closure element slides into the flow to shut off the stream. Globe and [[Pinch Valves]] are other types of linear motion devices. [[Needle Valves]] have a slender, tapered point at the end of a valve stem. [[Poppet Valves]] open and close ports with a sealing device and spring. [[Plug Valves]] or stop-cock valves are designed for both on or off and throttling functions. Other types of plastic valves include [[Sanitary Valves]] or [[Hygienic Valves]], [[Sampling Valves]] or dispensing valves, [[Shut-Off Valves]], [[Solenoid Valves]], and [[Toggle Valves]].
There are many types of plastic valves. [[Ball Valves]] provide tight shut-offs, but are not suitable for sanitary applications. [[Butterfly Valves]] permit flow in only one direction. [[Check Valves]] are self-actuating and prevent the reversal of process flow. [[Diaphragm Valves]] separate the flow of gases from the closure element. Directional valves steer flow through selected passages. [[Diverter Valves]] redirect process flow. Drain valves reduce surplus media. Float valves open or close automatically as the level of a fluid changes. Foot valves are check valves with a built-in strainer. [[Gate Valves]] or knife valves are linear motion valves in which a closure element slides into the flow to shut off the stream. Globe and [[Pinch Valves]] are other types of linear motion devices. [[Needle Valves]] have a slender, tapered point at the end of a valve stem. [[Poppet Valves]] open and close ports with a sealing device and spring. [[Plug Valves]] or stop-cock valves are designed for both on or off and throttling functions. Other types of plastic valves include [[Sanitary Valves]] or [[Hygienic Valves]], [[Sampling Valves]] or dispensing valves, [[Shut-Off Valves]], [[Solenoid Valves]], and [[Toggle Valves]].
Selecting Plastic V
Selecting plastic valves requires an analysis of performance specifications, actuation methods, and connection types. Performance specifications include valve size, pressure rating, number of ports or ways, media temperature, and valve flow coefficient. Suppliers specify valves according to metric or English (imperial) measurements. Some plastic valves are actuated manually, by a hand wheel or crank, or with mechanical devices such floats and cams. Others are actuated by electric, pneumatic, electro-hydraulic, or electro-hydraulic methods. There are many connection types for plastic valves. Examples include compression fittings, bolt flanges, clamp flanges, union connections, tube fittings, butt welds, and socket welds. Plastic valves with internal or external threads for inlet or outlet connections are also available.
Uses
Plastic valves are used with a variety of media. Examples include powders, rendering wastes, sludge, slurry, ash slurry, coolants, hazardous materials, high viscosity fluids, hydraulic fluid, liquid metal, lubricants, air and compressed air, hot and cold water, salt water, wastewater, gasoline, diesel fuel, liquefied petroleum gas (LPG), natural gas, abrasive materials, acids, and adhesives.








 
==Uses==
 
Plastic valves are used with a variety of media. Examples include powders, rendering wastes, sludge, slurry, ash slurry, coolants, hazardous materials, high viscosity fluids, hydraulic fluid, liquid metal, lubricants, air and compressed air, hot and cold water, salt water, wastewater, gasoline, diesel fuel, liquefied petroleum gas (LPG), natural gas, abrasive materials, acids, and adhesives.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
plastic valves provide a dependable and economical way to handle corrosive chemicals, including sulfuric and hydrofluoric acid, nitric acid, oxidizing chemicals, caustics, solvents, halogens, and various other hostile fluids.
 
They perform at temperatures up to 250ºF, pressures up to 230 psi, and flows up to 18,500 gpm.
Understanding the benefits and limitations of both advanced plastics and metals is essential to making an informed choice in valve materials. For services up to 250ºF and pressures up to 230 psi, plastic valves outperform metal with respect to corrosion, abrasion and freeze resistance, and lower installed cost. Over 70% of all industrial valve applications fall within these ranges. In high pressure, high temperature applications, metals are your only choice. For all other process lines, from wet chlorine, plating solutions, and acid wastes to demineralized water, plastic valve and piping materials are your best solution. Knowing the compatibility of the process material with the valve materials of construction, which include body, seat, seals, gaskets, diaphragms, discs, plugs,balls, packings and trims – non-wetted as well as wetted parts – impacts the valve's life and performance and contributes to its overall cost. In this catalog we have made every attempt to provide you with information which will allow you to make the right selection.
The advantages of using plastics are constantly being discovered. Over the past few years, there has been a dramatic increase in the application of plastic valves and piping systems in areas where metal valves were thought to be the only solution. Even the most corrosion resistant metals are still susceptible to galvanic and electrolytic corrosion, resulting in scale build-up which reduces flow rates and increases pressure drop. Asahi/America is actively trying to educate end users to upgrade to plastic systems.
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