Q.
(a) Using suitable diagrams, explain the underground sewerage system for combined and separate systems. (15 marks)
(b) Explain four (4) types of materials that are used for water supply pipes. (10 marks)
(25 marks, 2016 Q3)
A.
a) Similar question was asked in
b) 4 types of materials used for water supply pipes.
1. Cast iron, Galvanized iron;
2. Copper, Chromed Brass, Chromed Copper;
3. Lead; (go here for further reading on lead use as water pipes - poisoning)
4. Plastic - PVC;
5. PEX (Cross-linked Polyethylene)
PVC has various types, uPVC or PVC. Regular PVC (polyvinyl chloride) is a common, strong but lightweight plastic used in construction. It is made softer and more flexible by the addition of plasticizers. If no plasticizers are added, it is known as uPVC (unplasticized polyvinyl chloride), rigid PVC, or vinyl siding in the U.S. There is another type which is cPVC.
uPVC vs. PVC Pipes
PVC is used as a replacement for copper and aluminum pipes and is used in waste lines, irrigation systems and pool circulation systems. It is easy to cut into smaller pieces and can be fastened with glue, making it a good alternative to metal.
uPVC is used for the majority of plastic pipes in the world, as it is incredibly resistant to chemical erosion and has smoother inner walls that help to encourage water flow. It also functions well in a wide range of temperatures and operating pressures. It is incredibly strong, stiff and cost-effective, and so is often used for sewage lines and exterior drainage pipes. Even so, uPVC piping is much less common in the U.S., where PVC piping is preferred.
Neither PVC nor uPVC is used to transmit drinking water. cPVC (chlorinated polyvinyl chloride) is used instead.
Good reading go here.
