ME444 ENGINEERING PIPING SYSTEM DESIGN

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 = 3.66 (Ns= 10,000) = 0.57 (Ns = 1,550)

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

17. Standard motor size

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 Pressure 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 5.1 200 lpm @ 50.85m.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. 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)

50. Example 6.3 (5) Dimension of NM12