Grade 10 building construction – Pipework Quiz
1. Which material is most commonly used for cold water supply pipes in Kenyan houses?
uPVC (PVC) is widely used for cold water supply because it is light, does not rust, is cheap, and easy to install compared with metal pipes.
2. Which type of pipe is commonly used for underground drainage and sewer lines?
PVC soil pipes are durable, do not corrode, and are suitable for underground drainage and sewer lines, making them common in Kenyan construction.
3. Which pipe fitting is used to change the direction of flow by 90 degrees?
An elbow fitting is specifically designed to change the direction of pipework, commonly by 90 degrees.
4. Which fitting is used to join three pipes together allowing flow in two directions from one pipe?
A tee fitting joins three pipes and allows one inlet to feed two outlets or combine two inlets into one outlet.
5. Which type of valve is best for quickly stopping or allowing flow in a water pipe?
A ball valve gives quick on/off control with a simple quarter-turn handle, making it ideal for fast shut-off.
6. Which valve prevents water from flowing backwards in a pipe system?
A check valve (non-return valve) allows flow in one direction only, preventing reverse flow that could contaminate clean water.
7. Which joining method uses a chemical solvent to bond plastic pipes permanently?
Solvent welding softens the plastic surfaces and fuses them together, creating a permanent, leak-proof joint for PVC pipes.
8. What is commonly used to seal threaded pipe joints to prevent leaks?
PTFE tape (plumber's tape) is wrapped on threads to seal and prevent leaks in threaded pipe connections.
9. What is the minimum recommended slope for a 100 mm soil pipe to ensure proper drainage?
A fall of about 1 in 40 provides enough gradient for waste to flow without blocking while avoiding too fast flow that could leave solids behind.
10. What device is fitted to reduce banging in pipes caused by sudden valve closure (water hammer)?
A water hammer arrestor or air chamber absorbs pressure surges when flow is suddenly stopped, preventing loud banging and damage.
11. Which test is commonly used to check for leaks in a newly installed water pipe system?
A hydrostatic test fills the system with water and applies pressure to reveal leaks before the system is put into service.
12. What colour is commonly used to identify cold water supply pipes?
Blue is the standard colour for cold water piping, helping plumbers and users distinguish it from hot water (often red).
13. Which pipe material will not rust even if exposed to moisture?
PVC is a plastic material that does not contain iron and therefore will not rust, unlike metal pipes.
14. What is the purpose of a foot valve on a borehole pump suction line?
A foot valve is a check valve at the pump suction that stops water returning to the well, maintaining the pump's prime.
15. Why are expansion loops or allowances provided in long hot water pipe runs?
Pipes expand when heated; expansion loops or joints give space for movement and prevent cracking or joint failure.
16. Which fitting is used to connect pipes of different diameters?
A reducer fitting changes the pipe diameter smoothly from larger to smaller or vice versa.
17. What is the main function of a trap (U-bend or P-trap) under a sink?
Traps hold a small amount of water that forms a seal, blocking sewer gases while allowing waste water to pass.
18. Which pipe material is traditionally preferred for hot water supply because it withstands heat well?
Copper pipes handle high temperatures and pressure well, making them a common choice for hot water systems.
19. What is the term for energy loss caused by fittings, bends and valves in a pipe system?
Losses due to fittings and fittings' turbulence are called minor losses (in contrast to major losses from pipe friction).
20. Which tool is best for making a clean cut in a small-diameter PVC water pipe?
A plastic pipe cutter gives a clean, square cut on PVC pipes and is safer and faster than using a hacksaw for small pipes.
21. Why are flanged joints used in some pipe systems?
Flanged joints can be unbolted so pipe sections and equipment can be removed or repaired without cutting the pipe.
22. Which material is most suitable for downpipes that carry rainwater from gutters?
PVC downpipes are lightweight, resist corrosion, and are commonly used for rainwater drainage in Kenyan homes.
23. Which fitting gives a more gradual change in direction than a sharp elbow, reducing flow resistance?
A bend is a longer, smoother curve that changes direction gradually, producing less turbulence than a sharp elbow.
24. Which valve is best for throttling or regulating flow rather than simply turning flow on or off?
A globe valve is designed to control flow rate and can be adjusted to regulate the flow precisely.
25. What simple pipework practice helps conserve water in a household?
Fixing leaks quickly prevents continuous water loss and is one of the easiest and most effective ways to conserve water.
26. Which material is commonly used for cold domestic water supply pipes in Kenyan houses?
uPVC (unplasticized PVC) is commonly used for cold water supply in Kenya because it is durable, non-corroding and inexpensive compared with metal or fragile materials.
27. What is the main purpose of a trap under a sink or sanitary appliance?
A trap holds a small water seal that blocks sewer gases from coming back into the building while still allowing wastewater to flow away.
28. Which fitting is used to change the direction of a pipe run?
An elbow fitting is designed to change the direction (angle) of a pipe, commonly 90° or 45° bends.
29. Which valve type is best for a fast on/off shut off in household plumbing?
A ball valve provides quick, full-bore on/off control with a simple quarter-turn handle, making it ideal for household shut-off.
30. Where is the water meter usually placed for a Kenyan residential property?
Water meters are normally installed at or near the property boundary where the water service from the main connects, so the provider can read and maintain it.
31. Which pipe material is most resistant to corrosion for underground drainage in Kenyan buildings?
PVC is non-metallic and resists chemical and soil corrosion, making it a common choice for underground drainage and sewer lines.
32. What is the purpose of a vent pipe in a drainage system?
Vent pipes allow air into the drainage system so that traps do not get siphoned dry and foul gases are safely exhausted to atmosphere.
33. Which of these is a common nominal bore size for a household cold water service pipe?
15 mm is a common small-bore nominal size used for domestic water service lines such as taps and short branch feeds.
34. What does a check valve (non-return valve) do in pipework?
A check valve permits fluid to flow forward but closes if flow reverses, preventing contamination from backflow.
35. Which joining method is commonly used for joining uPVC pipes in plumbing?
Solvent welding uses a special cement that softens and fuses uPVC surfaces to create a strong, watertight joint.
36. Why is pipe insulation important for hot water pipes in a house?
Insulating hot water pipes keeps water hotter for longer, reducing heat loss and saving energy and money.
37. Which material is commonly used for soil pipes where fire resistance is required?
Cast iron soil pipes have good fire resistance and sound-deadening properties, so they are often used where fire performance is needed.
38. What is a union used for in pipework?
A union is a removable joint that lets pipes be separated for maintenance without twisting the pipework.
39. Which fitting reduces pipe size from a larger to a smaller diameter?
A reducer fitting connects two pipes of different diameters and smoothly changes the flow area.
40. Why should water supply pipes be kept accessible rather than fully buried in walls where possible?
Accessible pipe runs allow detection and repair of leaks without major demolition, reducing repair cost and damage.
41. Which device reduces incoming mains pressure to a safe level for household plumbing?
A pressure reducing valve lowers high mains pressure to a constant, safer level to protect fixtures and appliances.
42. What is the usual purpose of a waste air admittance valve (AAV) in modern pipework?
An AAV allows air into the drainage system when needed to prevent trap siphonage, useful where a full vent to atmosphere is not possible.
43. Which practice helps prevent corrosion of steel water pipes in Kenya?
Galvanizing coats steel with zinc, forming a protective layer that reduces rust and prolongs pipe life.
44. For a typical domestic soil stack connected to WC pans, which nominal diameter is commonly used?
A 100 mm (4 inch) nominal soil pipe is commonly used for main soil stacks handling WC discharge in domestic buildings.
45. Which method is commonly used to test a new drainage system for leaks?
Water testing fills the drainage pipes and inspection chambers to a set level to detect leaks and ensure watertight joints.
46. Which fitting is used to join two pipes of the same diameter in a straight line?
A coupling is a straight connector used to join two pipes of the same nominal diameter in line.
47. Why should hot water storage pipes and tanks be protected from scalding in houses?
Protecting hot water systems with thermostatic controls, insulation and warnings reduces the risk of scalding and follows good safety practice.
48. Which Kenyan institution sets national product standards that can apply to plumbing materials?
KEBS develops and publishes national standards for products and materials, including plumbing pipes and fittings used in Kenya.
49. What is the main advantage of using plastic pipes (like uPVC) over unprotected metal pipes in water supply?
Plastic pipes resist corrosion, are lightweight and easier to handle than unprotected metal, making them popular for domestic plumbing.
50. Why should waste pipes from sinks and baths be installed with a slight slope?
A slight slope helps wastewater flow by gravity, reducing the chance of solids settling and causing blockages.