1. ME444 ENGINEERING PIPING SYSTEM DESIGN
CHAPTER 6 : PUMPS

2. LAST SESSION PIPING SYSTEM DESIGN PROCEDURE PIPE THICKNESS
PIPE SIZING AND SYSTEM PRESSURE DROP

3. CONTENTS Fundamental of Pumps Operating Point Pump Selection
Pump Installation

4. 1. Fundamental of Pumps
When source pressure is not enough to provide desired output, pump is utilized.
SOURCE
PIPING SYSTEM
END USERS

5. Pump output
Flow rate and Pressure rise.
Flow rate

6. Pump

7. Pump input and output Output = Flow rate and Pressure rise. Flow rate
Input energy

8. Specific Speed

9. Pump performance
Dynamic pump
Positive
displacement
pump

10. Pump performance range

11. Performance curves
= 0.57 (Ns = 1,550)
= 3.66 (Ns = 10,000)

12. Steep vs. flat curves
Flat curve for closed loop system with variable flow rate
Steep curve for high head and constant flow rate

13. Affinity law
Impeller Diameter
Impeller Speed

14. Example of performance curves

15. Example of performance curves

16. Speed of induction motor
poles
Synchronous speed
(rpm)
Possible Operating Speed (rpm) 2
3000
2850 4
1500
1425 6
1000
950 8
750
712 10
600
570

17. Standard motor size hp kW 1/8 0.09 1/6 0.12 1/4 0.18 1/3 0.25 1/2 0.37
3/4
0.55 1
0.75
1.5
1.1 2
2.5
1.85 3
2.2 hp kW 4 3
5.5
7.5 10 15 11 20 25
18.5 30 22 40 50 37 60 45

18. Effect of Fluid Viscosity

19. Net Positive Suction Head

20. Net Positive Suction Head Required
At low pressure, water can become vapor,
causing cavitations.
Suction pressure must be maintained above NPSHR
to avoid cavitation

21. Net Positive Suction Head Available
MUST Maintain NPSHA > NPSHR z
Suction lift
Vapor pressure
Pressure drop in suction piping

22. Patm vs Elevation

23. Example 6.1

25. 2. Operating Point Pump performance curve Operating point
System pressure drop curve

26. Filling a tank from bottom
Pump performance curve

27. Filling a tank from bottom vs. from top
Which way fill faster?

28. Throttling the discharge valve
Throttled valve
Fully open valve
Pump performance curve

29. Variable speed drive vs. valve throttling
Feedback
signal
Throttled valve
Fully open valve
Pump performance curve N1
Pump performance curve N2

30. VSD for pressure control
signal
Valve 1 and 2 open
All valve open
Pressure set point
Pump performance curve N1
Pump performance curve N2

31. Limitation of VSD
Feedback
signal
System curve
Cannot reduce speed

32. Parallel and Serial Connection
Do not exceed Maximum Allowable Working Pressure (MAWP)

33. Response to Parallel Connection

34. Parallel Connection of Pumps with Different Size

35. Utilization of Pressure Tank
Pressure Switch
Pressure Tank
Air
Water
Pressure in tank
Pump operate
Pump stop
time

36. Example 6.2

37. Example 6.2

38. Example 6.2

39. Example 6.2

40. Example 6.2

41. 3. Pump Selection Best Efficiency
Energy cost is far beyond the pump cost

42. Pump Specification

43. Pump Nameplate

44. IP RATING
The IP Code, International Protection Marking, IEC standard 60529, sometimes interpreted as Ingress Protection

45. Example 6.3 Select the suitable pump for Example 5.1
m.WG.

46. Example 6.3 (2)
Possible selections: NM12 and NM25/20
50.85 m
200 lpm

47. Example 6.3 (2)
Select NM12: Trim Diameter to 198 mm

48. Note: follow standard motor size
Example 6.3 (3)
Select NM12: Trim Diameter to 198 mm
Pump has efficiency of 49.5%
Power consumption 3.2 kW
Max power consumption 4kW
Select Motor size: 5.5kW
Note: follow standard motor size

49. Example 6.3 (4) hp kW
1/8
0.09
1/6
0.12
1/4
0.18
1/3
0.25
1/2
0.37
3/4
0.55 1
0.75
1.5
1.1 2
2.5
1.85 3
2.2 hp kW 4 3
5.5
7.5 10 15 11 20 25
18.5 30 22 40 50 37 60 45

50. Example 6.3 (5)
Dimension of NM12

51. Example 6.4
Back to example 5.3, if two identical pump of the following curve is installed,
predict the operating point.

52. Example 6.4 (2) 23.1m.WG. = 21.6m.WG  Variable with flow rate
+ 1.5 m. WG. Elevation  Constant

53. Example 6.4 (3)
2 pumps
in parallel
Single
pump

54. 3. Pump Installation

55. Typical Installation

57. Suction Lift More suction lift = Less NPSHA  Cavitation
5 Meter lift is the maximum possible value
Foot Valve
Submersible pump

58. Priming

59. Self Priming Pump

60. Pumping from Tank
Vent
Mak-up
Overflow
Drain
Vortex prevention plate

61. Eccentric Reducer
CORRECT
INCORRECT

62. Installation photos

63. Installation photos

64. Pump Seal

65. Packing Seal

66. Mechanical Seal

67. Homework
Exercise 6.1 and 6.2

68. Case Study