LECTURE NOTES 13.pptxLECTURE NOTES 13.pptx

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1. LECTURE NOTES 13 PUMP SELECTION AND APPLICATION Pumps are used to deliver liquids through piping systems as shown in Fig. 13.1. They must deliver the desired volume flow rate of fluid while developing the required total dynamic head h a created by elevation changes, differences in the pressure heads and velocity heads, and all energy losses in the system . Total Head on a Pump : We will call this value of ha the total head on the pump . Some pump manufacturers refer to this as the total dynamic head(TDH ) .

2. PUMP SELECTION AND APPLICATION Power Delivered by a Pump to the Fluid : I n Lecture Notes 7 to use the efficiency of the pump e M to determine the power input to the pump P 1. Pump Efficiency: Power Input to a Pump : There are many types of pumps described in this n otes: C entrifugal pumps for general transfer of fluids from a source to a destination . P ositive displacement pumps for fluid power systems that may require very high pressures . D iaphragm pumps that may be used to pump unwanted water from a construction site . J et pumps that provide drinking water to a farm home from a well . P rogressive cavity pump used to deliver heavy, viscous fluids to a materials processing system and others .

3. PUMP SELECTION AND APPLICATION After completing this notes , you should be able to : List the parameters involved in pump selection . List the types of information that must be specified for a given pump . Describe the basic pump classifications . List six types of rotary positive-displacement pumps . List three types of reciprocating positive-displacement pumps. List three types of kinetic pumps . Describe the main features of centrifugal pumps . Describe deep-well jet pumps and shallow-well jet pumps. Describe the typical performance curve for rotary positive-displacement pumps. Describe the typical performance curve for centrifugal pumps. State the affinity laws for centrifugal pumps as they relate to the rela tionships among speed, impeller diameter, capacity , total head capability, and power required to drive the pump . Describe how the operating point of a pump is related to the system resistance curve(SRC) . Define the net positive suction head required ( NPSH R ) for a pump and discuss its significance in pump performance .

4. PUMP SELECTION AND APPLICATION Describe the importance of the vapor pressure of the fluid in relation to the NPSH . Compute the NPSH available(NPSH A ) for a given suction line design and a given fluid . Define the specific speed for a centrifugal pump and discuss its relationship to pump selection . Describe the effect of increased viscosity on the performance of centrifugal pumps . Describe the performance of parallel pumps and pumps connected in series . Describe the features of a desirable suction line design . Describe the features of a desirable discharge line design . Consider the life cycle cost(LCC ) for the pump, the entire system cost, and the operating cost over time, not just the acquisition price of the pump itse lf.

5. PARAMETERS INVOLVED IN PUMP SELECTION When selecting a pump for a particular application , the following factors must be considered : The nature of the liquid to be pumped . The required capacity (volume flow rate ) . The conditions on the suction (inlet ) side of the pump . The conditions on the discharge (outlet ) side of the pump . The total head on the pump (the term h a from the energy equation ) . The type of system to which the pump is delivering the fluid . The type of power source (electric motor, diesel engine, steam turbine, etc .) . Space, weight, and position limitations . Environmental conditions, governing codes, and standards . Cost of pump purchase and installation . Cost of pump operation. The total LCC for the pumping system .

6. PARAMETERS INVOLVED IN PUMP SELECTION After pump selection, the following items must be specified: Type of pump and manufacturer . Size of pump. Size of suction connection and type (flanged , screwed, etc .) . Size and type of discharge connection . Speed of operation. Specifications for driver (e.g ., for an electric motor power required , speed, voltage, phase, frequency, frame size , enclosure type ) . Coupling type, manufacturer, and model number . Mounting details. Special materials and accessories required, if any . Shaft seal design and seal materials . Pump catalogs and manufacturers representatives supply the necessary information to assist in the selection and specification of pumps and accessory equipment.

7. TYPES OF PUMPS Pumps are typically classified as either positive displacement or kinetic pumps . Table 13.1 Classification of types of pumps . Positive displacement pumps deliver a specific volume of fluid for each revolution of the pump shaft or each cycle of motion of the active pumping elements . They often produce very high pressures at moderate volume flow rates . Kinetic pumps operate by transferring kinetic energy from a rotating element, called an impeller, to the fluid as it moves into and through the pump .

8. POSITIVE DISPLACEMENT PUMPS Gear Pumps. Figure 7.2 . in l ecture notes 7 shows the typical configuration of a gear pump that is used for fluid power applications and for delivering lubricants to specific machinery components . Gear pumps develop system pressures in the range of 1500 psi to 4000 psi (10.3 MPa to 27.6 MPa ). Delivery varies with the size of the gears and the rotational speed, which can be up to 4000 rpm. Deliveries from I to 50 gal/min (4-190 L/min) are possible with different size units . Advantages of gear pumps include low pulsation of the flow , good capability for handling high viscosity fluids, and it can be operated in either direction

9. POSITIVE DISPLACEMENT PUMPS Piston Pumps for Fluid Power . Figure 7.3 shows an axial piston pump, which uses a rotating swash plate that acts like a cam to reciprocate the pistons . Pressure capacity ranges up to 5000 psi (34.5 MPa ) .

10. POSITIVE DISPLACEMENT PUMPS Vane Pumps . T he vane pump (Fig . 13.3) consists of an eccentric rotor containing a set of sliding vanes that ride inside a housing. . A cam ring in the housing controls the radial position of the vanes . Typical pressure capacities are from 2000 to 4000 psi (13.8 to 27.6 MPa )

11. POSITIVE DISPLACEMENT PUMPS Screw Pumps . One disadvantage of the gear, piston, and vane pumps is that they deliver a pulsating flow to the output because each functional element moves a set, captured volume of fluid from suction to discharge . Screw pumps do not have this problem . Figure 13.3 shows a screw pump in which the central, thread-like power rotor meshes closely with the two idler rotors, creating an enclosure inside the housing that moves axially from suction to discharge, providing a continuous uniform flow . Screw pumps operate at nominally 3000 psi(20.7 MPa ) .

12. POSITIVE DISPLACEMENT PUMPS Progressing Cavity Pumps . The progressing cavity pump, shown in Fig. 13.4, also produces a smooth, non-pulsating flow and is used mostly for the delivery of process fluids rather than hydraulic applications . . Flow capacities range up to 1860 gal/min (7040 L/min) and pressure capability is up to 900 psi (6.2 MPa ) .

13. POSITIVE DISPLACEMENT PUMPS Lobe Pumps . The lobe pump (Fig . 13.5), sometimes called a cam pump, operates in a similar fashion to the gear pump . Advantages include very low pulsation of the flow, capability of handling large solids content and slurries, and that it is self-priming .

14. POSITIVE DISPLACEMENT PUMPS Piston Pumps for Fluid Transfer . Piston pumps used for fluid transfer are classified as either single-acting simplex or double-acting duplex types as shown in Fig. 13.6 . In principle, these are similar to the fluid power piston pumps, but they typically have a larger flow capacity and operate at lower pressures .

15. POSITIVE DISPLACEMENT PUMPS Diaphragm Pumps . In the diaphragm pump shown in Fig. 13.7, a reciprocating rod moves a flexible diaphragm within a cavity, alternately discharging fluid as the rod moves to the left and drawing fluid in as it moves to the right . One advantage of this type of pump is that only the diaphragm contacts the fluid, eliminating contamination from the drive elements . Large-diaphragm pumps are used in construction, mining , oil and gas, food processing, chemical processing, wastewater processing, and other industrial applications

16. Diaphragm Pumps .

17. POSITIVE DISPLACEMENT PUMPS Peristaltic Pumps . Peristaltic pumps (Fig . 13.8) are unique in that the fluid is completely captured with in a flexible tube throughout the pumping cycle. The tube is routed between a set of rotating rollers and a fixed housing . The rollers squeeze the tube, trapping a given volume between adjacent rollers . The design effectively eliminates the possibility of contaminating the product, making it attractive for chemical, medical, food processing , printing, water treatment, industrial, and scientific applications .

18. POSITIVE DISPLACEMENT PUMPS Performance Data for Positive Displacement Pumps: The operating characteristics of positive-displacement pumps make them useful for handling such fluids as water, hydraulic oils in fluid power systems, chemicals , paint, gasoline, greases , adhesives, and some food products . In general, they are used for high pressure applications requiring a relatively constant delivery Some disadvantages of so me designs include pulsating output, susceptibility to damage by solids and abrasives, and need for a relief valve . 1 . Reciprocating Pump Performance. In its simplest form, the reciprocating pump (Fig . 13.6) employs a piston that draws fluid into a cylinder through an intake valve as the piston draws away from the valve . Then, as the piston moves forward, the intake valve closes and the fluid is pushed out through the discharge valve. Such a pump is called simplex, and its curve of discharge versus time looks like that shown in Fig. 13.9(a ) . The resulting intermittent delivery is often undesirable. If the piston is double acting or duplex , one side of the piston delivers fluid while the other takes fluid in, resulting in the performance curve shown in Fig . 13.9(b ) .

19. POSITIVE DISPLACEMENT PUMPS

20. POSITIVE DISPLACEMENT PUMPS 2. Rotary Pump Performance. Figure 13.10 shows a typical set of performance curves for rotary pumps such as gear, vane, screw, and lobe pumps. It is a plot of capacity, efficiency, and power versus discharge pressure . Volumetric efficiency is a measure of the ratio of the volume flow rate delivered by the pump to the theoretical delivery, based on the displacement per revolution of the pump, times the speed of rotation . This efficiency is usually in the range from 90 percent to 100 percent, decreasing with increasing pressure in proportion to the decrease in capacity . Overall efficiency is a measure of the ratio of the power delivered to the fluid to the power input to the pump. Included in the overall efficiency is the volumetric efficiency, the mechanical friction from moving parts, and energy losses from the fluid as it passes through the pump . O verall efficiency ranging from 80 percent to 90 percent .

21. KINETIC PUMPS Kinetic pumps add energy to the fluid by accelerating it through the action of a rotating impeller . Figure 13.11 shows the basic configuration of a radial flow centrifugal pump, the most common type of kinetic pump

22. KINETIC PUMPS Figure 13.12 shows the basic design of radial, axial, and mixed-flow impellers . The propeller type of pump ( axial flow ) depends on the hydrodynamic action of the propeller blades to lift and accelerate the fluid axially, along a path parallel to the axis of the propeller .

23. KINETIC PUMPS Jet pumps Jet pumps , frequently used for household water systems, are composed of a centrifugal pump along with a jet or ejector assembly Figure 13.13 shows a typical deep-well jet pump configuration where the main pump and motor are located above ground at the top of the well and the jet assembly is down near the water leve l. T hen the water is Iifted through a single suction pipe, as shown in Fig. 13.14

24. KINETIC PUMPS Small centrifugal pump Figure 13.16 Small centrifugal pump with integral motor for use in appliances and similar applications . Although most of the centrifugal pump styles discussed thus far are fairly large and have been designed for commercial and industrial applications, small units are available for use in small appliances such as clothes washers and dishwashers, fountains , machine cooling systems, and other small-scale products .

25. KINETIC PUMPS Submersible Pumps Submersible pumps are designed so the entire assembly of the centrifugal pump, the drive motor, and the suction and discharge apparatus can be submerged in the fluid to be pumped . Figure 13.15 shows one design that has the sealed, vertical-shaft motor integrally mounted on top with a waterproof electrical connection . These pumps are useful for removing unwanted water from construction sites, mines, utility manholes, industrial tanks, waste water treatment facilities , and shipboard cargo holds .

26. KINETIC PUMPS Self-Priming Pumps Figure 13.17 shows one of several styles of self-priming pumps . The enlarged inlet chamber retains some of the liquid inside the housing during periods of shutdown with the action of the check valve in the suction port .

27. KINETIC PUMPS Column Pumps When drawing fluid from a tank, sump, or other source with moderate depth, the column pump like that shown in Fig . 13.8 is a useful design to consider .

28. KINETIC PUMPS Centrifugal Grinder Pumps When it is necessary to pump liquids containing a variety of solids, a submersible pump with a built-in grinder is a good solution . Figure 13.19 shows a design that sits at the bottom of a tank or sump and handles sewage, laundry or dishwasher effluent, or other wastewater .

29. PERFORMANCE DATA FOR CENTRIFUGAL PUMPS Because centrifugal pumps are not positive-displacement types , there is a strong dependency between capacity and the pressure that must be developed by the pump . This makes their performance ratings somewhat more complex . The typical rating curve plots the total head on the pump ( h a ) versus the capacity or discharge ( Q ) , as shown in Fig. 13.20 .

30. PERFORMANCE DATA FOR CENTRIFUGAL PUMPS Figure 13.21 shows a more complete performance rating of a pump, superimposing head , efficiency, and power curves and plotting all three versus capacity . The efficiency and power required are also important to the successful operation of a pump . Normal operation should be in the vicinity of the peak of the efficiency curve, with peak efficiencies in the range of 60-80 percent being typical for centrifugal pumps .

31. AFFINITY LAWS FOR CENTRIFUGAL PUMPS Most centrifugal pumps can be operated at different speeds to obtain varying capacities . In addition, a given size of pump casing can accommodate impellers of differing diameters . It is important to understand the manner in which capacity , head, and power vary when either speed or impeller diameter is varied . These relationships, called affinity laws . The symbol N refers to the rotational speed of the impeller, usually in revolutions per minute (r/min , or rpm ) .

32. AFFINITY LAWS FOR CENTRIFUGAL PUMPS

33. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS T he basic data needed to specify a suitable pump for a given system is the required volume flow rate , called capacity , and the total head, h a for the system in which the pump is to operate . Figure 13.22 shows an example of a composite rating chart for one line of pumps operating at a speed of 3500 rpm , which allows the quick determination of the pump size . The 2 X 3 - 10 centrifugal pump is one with a 2-in discharge connection, a 3-in suction connection , and a casing that can accommodate an impeller with a diameter of 10 in or smaller .

34. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS

35. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Effect of Impeller Size

36. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Effect of Speed

37. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Power Required

38. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Efficiency

39. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Net Positive Suction Head Required ( NPSH R )

40. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Complete Performance Chart

41. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS

42. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Additional Performance Charts

43. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Additional Performance Charts

44. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Additional Performance Charts

45. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Additional Performance Charts

46. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Additional Performance Charts

47. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Additional Performance Charts

48. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Additional Performance Charts

49. MANUFACTURERS DATA FOR CENTRIFUGAL PUMPS Additional Performance Charts For Smaller Centrifugal Pumps

50. NET POSITIVE SUCTION HEAD NPSH The descriptions of the several aspects of the performance of centrifugal pumps in the preceding sections emphasized the importance of the net positive suction head , NPSH . The basic issues include : Preventing a condition called cavitation , because of its extreme detrimental effects on the pump . The effect of the vapor pressure of the fluid being pumped on the on set of cavitation . The piping system design considerations that affect NPSH . The NPSH R for the selected pump must be satisfied . Cavitation When the suction pressure at the pump inlet is too low, vapor bubbles form in the fluid in a manner similar to boiling . The design of the suction piping system must provide a sufficiently high pressure that will avoid the development of cavitation in which vapor bubbles form within the flowing fluid. When cavitation occurs, the performance of the pump is severely degraded as the volume flow rate delivered drops. The pump vibrates and becomes noisy, giving off a loud, rattling sound as if gravel was flowing with the fluid . If this was allowed to continue, the pump would be destroyed in a short time .

51. NET POSITIVE SUCTION HEAD NPSH Vapor Pressure The fluid property that determines the conditions under which vapor bubbles form in a fluid is its vapor pressure P vp , typically reported as an absolute pressure in the units of kPa absolute or P sia . When both vapor and liquid forms of a substance exist in equilibrium, there is a balance of vapor being driven off from the liquid by thermal energy and condensation of vapor to the liquid because of the attractive forces between molecules . The pressure of the liquid at this condition is called the vapor pressure. A liquid is called volatile if it has a relatively high vapor pressure and vaporizes rapidly at ambient conditions Following is a list of six familiar liquids , ranked by increasing volatility: water, carbon tetrachloride , acetone, gasoline, ammonia, and propane . Several standards have been established by ASTM International to measure vapor pressure for different kinds of fluids . In the discussion of net positive suction head that follows, it is pertinent to use the vapor pressure head h vp rather than the basic vapor pressure P vp where

52. NET POSITIVE SUCTION HEAD NPSH

53. NET POSITIVE SUCTION HEAD NPSH

54. NET POSITIVE SUCTION HEAD NPSH

55. NET POSITIVE SUCTION HEAD NPSH NPSH Pump manufacturers test each pump design to determine the level of suction pressure required to avoid cavitation, reporting the result as the net positive suction head required, NPSH R , for the pump at each operating condition of capacity (volume flow rate) and total head on the pump . It is the responsibility of the pump system designer to ensure that the available net positive suction head, NPSH A , is significantly above NPSH R . Standards have been set jointly by the American National Standards Institute (ANSI) and the Hydraulic Institute ( HI) calling for a minimum of a 10 percent margin for NPSH A over NPSH R . NPSH Margin We can define the NPSH margin M to be : Higher margins, up to 100 percent, are expected for critical applications such as flood control, oil pipelines, and power generation service . Some designers call for a margin of 5.0 ft for large pumping systems . See ANSI/HI 9.6.1, Standard for Centrifugal and Vertical Pumps for NPSH Margin

56. NET POSITIVE SUCTION HEAD NPSH NPSH A The value of NPSH A is dependent on the vapor pressure of the fluid being pumped, energy losses in the suction piping, the elevation of the fluid reservoir, and the pressure applied to the fluid in the reservoir . Figure 13.38(a) includes a pressurized reservoir placed above the pump. Part (b) shows the pump drawing fluid from an open reservoir below the pump

57. NET POSITIVE SUCTION HEAD NPSH

58. NET POSITIVE SUCTION HEAD NPSH

59. NET POSITIVE SUCTION HEAD NPSH

60. SUCTION LINE DETAILS The suction line refers to all parts of the flow system from the source of the fluid to the inlet of the pump . Figure 13.38 shows two methods of providing fluid to a pump . In f ig . 13.38(a ), a positive head is created by placing the pump below the supply reservoir. This is an aid in ensuring a satisfactory NPSH. In addition, the pump will always be primed with a column of liquid at start-up . In f ig . 13.38(b), a suction lift condition occurs because the pump must draw liquid from below. Most positive displacement pumps can lift fluids about 8 m(26 ft ) . For most centrifugal pumps, however, the pump must be artificially primed by filling the suction line with fluid . This can be done by providing an auxiliary supply of liquid during start-up or by drawing a vacuum on the pump casing, causing the fluid to be sucked up from the source .

61. DISCHARGE LINE DETAILS

62. DISCHARGE LINE DETAILS In general, the discharge line should be as short and direct as possible to minimize the head on the pump . Elbows should be of the standard or long-radius type if possible . Pipe size should be chosen according to velocity or allowable friction losses . As shown in Fig. 13.39, other elements may be added to the discharge line as required. A pressure relief valve will protect the pump and other equipment in case of a blockage of the flow or accidental shut-off of a valve. A check valve prevents flow back through the pump when it is not running and it should be placed between the shut-off valve and the pump. If an enlarger is used from the pump discharge port it should be placed between the check valve and the pump . A tap into the discharge line for a gauge with its shut-off valve is highly recommended . Combined with the pressure gauge in the suction line, the operator can determine the total head on the pump and compare that to design requirements . A sample cock will allow a small flow of the fluid to be drawn off for testing without disrupting operation.

63. THE SYSTEM RESISTANCE CURVE The operating point of a pump is defined as the volume flow rate it will deliver when installed in a given system and working against a particular total head . The piping system typically includes several elements described in previous sections on the design of suction and discharge lines; valves, elbows , process elements, and connecting straight lengths of pipe . The pump must accomplish the following tasks : Elevate the fluid from a lower tank or other source to an upper tank or destination point . Increase the pressure of the fluid from the source point to the destination point. Overcome the resistance caused by pipe friction, valves, and fittings . Overcome the resistance caused by processing elements . Supply energy related to the operation of flow control valves that inherently cause changes to the system head to achieve the desired flow rates . The first two items in this list are components of the static head , h , for the system, where the name refers to the fact that the pump must overcome these resistances before any fluid begins to move, that is, the fluid is static . The static head h , is defined as,

64. THE SYSTEM RESISTANCE CURVE But the pump is expected to work against a higher head and, in fact, to deliver fluid to the system at a specified rate . As soon as fluid starts to flow through the pipes, valves, fittings, and processing elements of the system, more head is developed because of the energy losses that occur. Reca ll that the energy losses are proportional to the velocity head in the pipes (v2/2g ) and, therefore, they increase according to the square of the volume flow rate . This causes the characteristic shape of a system resistance curve (SRC ) , sometimes called a second degree curve, as shown in Fig. 13.40 .

65. THE SYSTEM RESISTANCE CURVE

66. THE SYSTEM RESISTANCE CURVE

67. THE SYSTEM RESISTANCE CURVE

68. THE SYSTEM RESISTANCE CURVE

69. THE SYSTEM RESISTANCE CURVE

70. PUMP SELECTION AND THE OPERATING POINT FOR THE SYSTEM Guidelines for Pump Selection Given the desired operating point for the system with the desired flow rate and the expected total head on the pump : Seek a pump with high efficiency at the design point and one for which the operating point is near the best efficiency point(BEP ) for the pump . Standards set jointly by the American National Standards Institute(ANSI ) and the Hydraulic Institute(HI ) call for a preferred operating region(POR ) for centrifugal pumps to be between 70 percent and 120 percent of the BEP . See Standard ANSI/HI 9.6.3-2012, Standard for Centrifugal and Vertical Pumps for Allowable Operating Region . Guidelines for Pump Selection For the selected pump, specify the model designation, speed , impeller size, and the sizes for the suction and discharge ports . At the actual operating point, determine the power required , the actual volume flow rate delivered, efficiency, and the NPSH R . Also, check the type of pump, mounting requirements, and types and sizes for the suction and discharge lines to ensure that they are compatible with the intended installation . Compute the NPSH A for the system . Ensure that NPSHA > 1.10 NPSH R for all expected operating conditions .

71. PUMP SELECTION AND THE OPERATING POINT FOR THE SYSTEM Guidelines for Pump Selection If necessary, provide a means of connecting the specified pipe sizes to the connections for the pump if they are of different sizes. Use a gradual reducer or a gradual expander to minimize energy losses added to the system by these elements .

72. PUMP SELECTION AND THE OPERATING POINT FOR THE SYSTEM

73. PUMP SELECTION AND THE OPERATING POINT FOR THE SYSTEM

74. PUMP SELECTION AND THE OPERATING POINT FOR THE SYSTEM

75. PUMP SELECTION AND THE OPERATING POINT FOR THE SYSTEM

76. PRACTICE PROBLEMS For a given size of centrifugal pump casing, if the diameter of the impeller is reduced by 25 percent, how much does the capacity change ? For a given size of centrifugal pump casing, if the diameter of the impeller is reduced by 25 percent, how much does the total head capability change ? For a given size of centrifugal pump casing, if the diameter of the impeller is reduced by 25 percent, how much does the power required to drive the pump change ? Describe each part of this centrifugal pump designation: 1 ½ x 3 - 6 . ? For the line of pumps shown in Fig. 13.22, specify a suitable size for delivering 100 gal/min of water at a total head of 300 ft . ? For the 2 x 3 - 10 centrifugal p um p performance curve shown in Fig. 13.28, describe the performance that can be expected from a pump with an 8-in impeller operating against a system head of 200 ft. Give the expected capacity, the power required, the efficiency, and the required NPSH . ? For the 2 x 3 - 10 centrifugal pump performance curv e sho wn in Fig. 13.28, list the total head and capacity at which the pump will operate at maximum efficiency for each of the impeller sizes shown . ?

77. PRACTICE PROBLEMS Determine the available NPSH for the system shown in Fig . 13.38{b). The fluid is water at 80°C and the atmospheric pressure is 101.8 kPa . The water level in the tank is 2.0 m below the pump inlet. The vertical leg of the suction line is a DN 80 Schedule 40 steel pipe, whereas the hori zo ntal leg is a DN 50 Schedule 40 pipe, 1.5 m long. The elbow is of the long-radius type. Neglect the loss in the reducer. The foot valve and strainer are of the hinged disk type . The flow rate is 300 L/min.