Building Water Supply System: QUIZ / STUDY QUESTIONS

2. What is residual water pressure?

3. Identify and describe the two basic types of water sup ply distribution systems used in buildings, and where each will be used.

4. What are the factors that dictate the minimum and maximum water velocity in a plumbing system?

5. What is cavitation and where might it occur?

6. What is a cross-connection and where might it occur?

7. What is water hammer, and how can it be reduced in the system?

8. How can thermal expansion damage a pipe?

9. What types of pipe materials expand the most with temperature increase?

10. What are the two basic types of water supply systems used?

11. How can freezing water damage a pipe and how does damage occur?

12. How can heated water damage a pipe and how does damage occur?

13. What effect does aging have on different types of pipe?

14. Why is pipe insulation necessary and where is it used?

15. During what hours does water usage peak in a home?

16. What is a fixture unit and where is it used?

17. What is meant, in water supply systems, by static head and friction head?

18. Describe the terms cold water, chilled water, heated water, and tempered water.

19. What is the difference between a storage tank water heater and an instantaneous water heater?

20. Why is more than one storage tank water heater some times used in larger residences?

21. What is the difference between recirculating and non circulating hot water systems, and where would the circulating system most likely be used?

22. Describe the operation of the two types of pumps commonly used in buildings. Which type of pump is most common?

23. With respect to a pump, what is pump capacity?

24. With respect to a pump, what is total dynamic head?

25. With respect to a pump, what is brake horsepower?

26. With respect to a pump, what is net positive suction head?

27. With respect to a pump, what is a pump performance curve?

28. What are parallel and series pumping?

29. What is the difference between hard and soft water?

30. What are the two main problems with hard water in plumbing systems?

31. What are the two types of water softening methods and how do they function? Design Exercises

32. Using the velocity design method, determine the mini mum required size of hot and cold water supply pipes serving an apartment containing a kitchen sink, dish washer, lavatory, bathtub, and tank-type water closet.

Use a maximum velocity of 8 ft/s. Base pipe size on Type L copper tube (Table 9 in Section 12).

33. Using the velocity design method, determine the mini mum required size of hot and cold water supply pipes serving 8 apartments, each containing a kitchen sink, dishwasher, lavatory, bathtub, and tank-type water closet. Use a maximum velocity of 8 ft/s. Base pipe size on Type L copper tube (Table 9 in Section 12).

34. A plumbing fixture outlet is 18 ft above the water service line. Pressure available at the water service is 80 psi.

Determine the change in pressure from elevation.

35. A plumbing fixture outlet is 120 ft above the water service line. Pressure available at the water service is 80 psi.

Determine the change in pressure from elevation.

36. Determine the pressure drop across a 3/4-in diameter Type L copper pipe that is 60 ft long and is carrying water at 12 gpm.

37. Determine the pressure drop across a 3-in diameter Type L copper pipe that is 80 ft long and is carrying water at 120 gpm.

38. A plumbing branch is composed of 68 ft of 1-in diameter Type L copper pipe, three 90° elbows, and a gate valve. The elevation increase is 12 ft. Determine the total pressure drop across the plumbing branch if it’s carrying water at 45 gpm.

39. Estimate the peak hot water demand of a household that has a morning routine of three showers, two hands/face washings, five teeth brushings, food preparation, and automatic dishwashing.

40. Determine the demand load of water required for the apartment building .

41. Size an instantaneous water heater to meet the following conditions:

• Two hot water faucets open with a flow rate of 0.75 gpm

• Two persons showering using showerheads with a flow rate of 2.0 and 2.5 gpm

• An inlet water temperature is 40°F (4°C)

• Water must be heated to 120°F (49°C)

42. Estimate the peak hot water demand of an 18-unit condominium having a single water heating system. Each unit has two full bathrooms and a clothes washing machine. Calculate the minimum storage tank size for this water heating system.

43. Design an upfeed water supply system for the apartment building. Use Type L copper pipe for this design problem. Assume each apartment has its own storage tank water heater.

44. Determine the hot water consumption and the equipment sizes required for the.

45. Determine the hot water consumption and the equipment sizes required for a 150-room motel based on the following information:

• Hot water required: 30 gal per day per person

• Occupancy rate: 2.4 persons per room, 100% occupied

• Storage capacity (tank): 60% of total daily use (of which 75% is usable)

• Maximum hourly demand: 1/6 of total daily use

• Peak demand time: 3 hr

46. Design the upfeed hot water supply system required for the apartment. Use copper pipe and tubing.

47. A pump with an 8-in diameter impeller is operating at 1750 rpm and delivering 40 gpm with a total dynamic head of 55 ft. The pump's brake horsepower (BHP) is 1.2 hp under these conditions. Assume constant efficiency.

a. Approximate the pump's capacity if impeller size is increased to 10 in.

b. Approximate the pump's capacity if pump speed is increased to 3450 rpm.

c. Approximate the pump's total dynamic head if impeller size is increased to 10 in.

d. Approximate the pump's total dynamic if pump speed is increased to 3450 rpm.

e. Approximate BHP if impeller size is increased to 10 in.

f. Approximate BHP if pump speed is increased to 3450 rpm.

48. A pump with an 8-in diameter impeller is operating at 1750 rpm and delivering 40 gpm with a total dynamic head of 55 ft. The pump's BHP is 1.2 hp under these conditions. Approximate the capacity (Q), total dynamic head (?PTDH), and BHP if impeller size is increased to 10 in and pump speed is increased to 3450 rpm.

49. A pump with a 150-mm diameter impeller is operating at 1750 rpm and delivering 3.2 L/s with a total dynamic head of 16 meters. The pump's BHP is 3.4 kW (0.45 hp) under these conditions. Assume constant efficiency.

a. Approximate the pump's capacity if impeller size is increased to 200 mm.

b. Approximate the pump's capacity if pump speed is increased to 3450 rpm.

c. Approximate the pump's total dynamic head if impeller size is increased to 200 mm.

d. Approximate the pump's total dynamic if pump speed is increased to 3450 rpm.

e. Approximate BHP if impeller size is increased to 200 mm.

f. Approximate BHP if pump speed is increased to 3450 rpm.

50. A pump with a 150-mm diameter impeller is operating at 1750 rpm and delivering 3.2 L/s with a total dynamic head of 16 meters. The pump's BHP is 3.4 kW (0.45 hp) under these conditions. Approximate the capacity (Q), total dynamic head (?PTDH), and BHP if impeller size is increased to 200 mm and pump speed is increased to 3450 rpm.

51. Design conditions for a piping system are that the pump must deliver water at a flow rate of 180 gpm and generate 50 ft of total dynamic head to overcome the static head and friction head of the piping system.

a. Based on pump performance curves in fgr.23, size a pump impeller and drive that can meet these conditions.

b. Find water efficiency and net positive suction head required at the design conditions.

52. Design conditions for a piping system are that the pump must deliver water at a flow rate of 120 gpm and generate 100 ft of total dynamic head to overcome the static head and friction head of the piping system.

a. Based on pump performance curves in fgr.23, size a pump impeller and drive that can meet these conditions.

b. Find water efficiency and net positive suction head required at the design conditions.

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