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.
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.
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.