Machinery's Handbook, 31st Edition
2768 Plastic Pipe PVC and chlorinated PVC (CPVC) are related, but CPVC can withstand a wider range of temperatures. PVC is limited to 140°F while CPVC can be used up to 190°F. PVC has inherently superior fire retarding properties due to its chlorine content. The ignition tem perature of PVC is as high as 455°C. PVC and CPVC are highly resistant to oxidation and are very durable. PVC is resistant to acids, bases, and most inorganic chemicals. PVC swells or dissolves in aromatic hydrocarbons, ketones, and cyclic ethers. These plastics crack when frozen, and CPVC requires more mechanical support than PVC. ABS pipes are used mainly in applications where rigidity and impact strength are needed. ABS can be tailored to a wide range of needs by altering its chemical composi- tion. It is suitable for water transport and has good resistance to a wide range of diluted inorganic acids, organic acids, salts, animal fats and oils. ABS is not resistant to organic solvents, alcohol, gasoline, acetic acid or vegetable oils. ABS is resistant to temperatures up to 70°C, but its pressure capacity must be derated with elevated temperature. ABS is non-toxic and is used for food and beverage applications. PE pipes can be joined through heat fusion, and are common in municipal water applications. They are extremely slippery when wet. PE Water Service lines are typically 1 ⁄ 2 to 3 nominal diameter pipe or tubing in accordance with AWWA C901, ASTM D2239, ASTM D3035, or ASTM D2737. PE water distribution lines are typically 4 to 12 nominal diameter pipe in accordance with AWWA C906, ASTM D3035, or ASTM F714. Install PE pressure pipe in accordance with ASTM D2774. PE pipe may be cold bent. The allow- able bend ratio is determined by the pipe diameter ( D ) and the Standard Dimension Ratio ( SDR ) in accordance with Table 10. Table 10. Cold Bend Radius, Polyethylene Pipe Standard Dimension Ratio, SDR Minimum Bend Radius to Centerline of Pipe 7 through 9 20 × Pipe Outside Diameter 11 through 13.5 25 × Pipe Outside Diameter 17 through 21 27 × Pipe Outside Diameter Fitting in Bend 100 × Pipe Outside Diameter PEX is gaining popularity for residential water service because it is flexible, does not corrode, is easy to work and connect, and is resistant to scale and chlorine. It is made from crosslinked HDPE and subject to ASTM F876. It can be bent according to table, as well as used with compression tube fittings. Standard PEX does admit some oxygen, so an added oxygen barrier may be needed in some applications. PEX can be used at temperatures from below freezing to almost boiling. Table 11. Bend Radius, PEX Pipe or Tube PEX Size, inch Outside Diameter, inch Minimum Bend Radius, inch 3 ⁄ 8 0.500 4 1 ⁄ 2 0.625 5 5 ⁄ 8 0.750 6 3 ⁄ 4 0.875 7 1 1.125 9 Schedules: Schedule number designations for plastic pipe are an indicator of wall thick ness. Schedules 40 and 80 are the most commonly used, and 120 is also widely available. For a given nominal pipe size, all schedules have the same outside diameter. Therefore, higher schedule pipes of the same diameter have smaller flow areas. The nominal pipe size
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