SYSTEM ONE

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SYSTEM ONE

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1. SYSTEM ONE

3. Maintenance vs. Capital What does a pump actually cost ? Most plants regard the pump as a commodity... purchased from the lowest bidder with little consideration for: The operation and maintenance cost of the pump over its life cycle... which could be 20 - 30 years Costs to be considered: Spare parts (inventory costs) Operation downtime (lost production) Labor to repair (maintenance costs) Power consumption based on pump efficiency Environmental, disposal, and recycle costs

4. TRUE PUMP COSTS Repair costs can easily exceed the price of a new pump (several times) over its life of 20 -30 years Documented Pump failures cost $4000 or more per incident ( parts and labor) If MTBF was improved from 1 to 2 years for a pump in a tough application Results in savings of $2000 /year over the life of the pump

7. RADIAL LOAD Operation of a pump away from the BEP results in higher radial loads ... creating vibration and shaft deflection

8. Radial Forces By design, uniform pressures exist around the volute at the design capacity (BEP) Resulting in low radial thrusts and minimal deflection. Operation at capacities higher or lower than the BEP Pressure distribution is not uniform resulting in radial thrust on the impeller Magnitude and direction of radial thrust changes with capacity (and pump specific gravity)

9. Most pumps do not operate at BEP: Due to improper pump selection (oversized) Changing process requirements (throttling) Piping changes Addition of more pipe, elbows and valves System head variations Change in suction pressure, discharge head req’d Buildup in pipes Filter plugged Automatic control valve shuts off pump flow Change in viscosity of fluid Parallel operation problems (starving one pump) Shaft Deflection

10. Impeller Radial Force At Any Flow F (lbs.,Kg)

12. PUMP SPECIFIC SPEED CLASSIFIES IMPELLERS ON THE BASIS OF PERFORMANCE AND PROPORTIONS REGARDLESS OF SIZE OR SPEED FUNCTION OF IMPELLER PROPORTIONS SPEED IN RPM AT WHICH AN IMPELLER WOULD OPERATE IF REDUCED PROPORTIONALLY IN SIZE TO DELIVER 1 GPM AND TOTAL HEAD OF 1 FOOT DESIGNATED BY SYMBOL Ns Ns = RPM(GPM)1/2 H3/4 RPM = SPEED IN REVOLUTIONS / MINUTE GPM = GALLONS /MINUTE AT BEST EFF. POINT H = HEAD IN FEET AT BEST EFF. POINT

13. PUMP SPECIFIC SPEED (Metric) CLASSIFIES IMPELLERS ON THE BASIS OF PERFORMANCE AND PROPORTIONS REGARDLESS OF SIZE OR SPEED FUNCTION OF IMPELLER PROPORTIONS SPEED IN RPM AT WHICH AN IMPELLER WOULD OPERATE IF REDUCED PROPORTIONALLY IN SIZE TO DELIVER 1 M3/h AND TOTAL HEAD OF 1 M DESIGNATED BY SYMBOL Ns Ns = RPM(M3/h) 1/2 M 3/4 RPM = SPEED IN REVOLUTIONS / MINUTE M3/h = CUBIC METERS PER HOUR AT BEST EFF. POINT MH = HEAD IN METERS AT BEST EFF. POINT

18. NET POSITIVE SUCTION HEAD (NPSH) One of the more difficult characteristics to understand In simplistic terms: Providing enough pressure in the pump suction to prevent vaporization of the fluid as it enters the eye of the impeller Two values to be considered: NPSH available Amount of pressure (head) in the system due to atmospheric or liquid pressure, height of suction tank, vapor pressure of the fluid and friction loss in the suction pipe

19. NPSH cont. NPSH required Pressure reduction of the fluid as it enters the pump Determined by the pump design Depends on impeller inlet, design, flow, speed and nature of liquid NPSH available must always be > NPSH required by a minimum of 3-5 feet (1-1.5m) margin

20. CAVITATION Results if the NPSH available is less than the NPSH required Occurs when the pressure at any point inside the pump drops below the vapor pressure corresponding to the temperature of the liquid The liquid vaporizes and forms cavities of vapor Bubbles are carried along in a stream until a region of higher pressure is reached where they collapse or implode with tremendous shock on the adjacent wall Sudden rush of liquid into the cavity created by the collapsed vapor bubbles causes mechanical destruction (cavitation erosion or pitting)

21. CAVITATION cont. Efficiency will be reduced as energy is consumed in the formation of bubbles Water @ 70oF (20oC)will increase in volume about 54,000 times when vaporized Erosion and wear do not occur at the point of lowest pressure where the gas pockets are formed, but farther upstream at the point where the implosion occurs Pressures up to 150,000 psi have been estimated at the implosion (1,000,000 Kpa)

31. BEARING OIL SEALS Rubber Lip Seals Provided To Protect Bearings in standard ANSI pumps Have life of less than four months Groove shaft in first 30 days of operation External contamination causes bearing failure

32. LIP SEAL LIFE AUTOMOBILE 100,000 Miles @ 40 Miles /hr. = 2500 hrs. of operation PUMP 24 hrs./day x 365 days / year = 8760 hours 60% of lip seals fail in under 2000 hours Lip seals may be fine for automobiles, but not for pumps

33. THRUST BEARING SNAP RING Thrust bearings in standard ANSI pumps are held in place with a snap ring Snap ring material harder than bearing housing Wear in bearing housing results in potential bearing movement Difficult to remove and install If installed backwards - potential loose bearing

35. SHAFT DYNAMICS Radial movement of the shaft occurs in 3 forms: Deflection - under constant radial load in one direction Whip - Cone shaped motion caused by unbalance Runout - Shaft bent or eccentricity between shaft sleeve and shaft It is possible to have all 3 events occurring simultaneously ANSI B73.1 and API 610 Limit radial deflection and runout of the shaft to 0.002 T.I.R. at the stuffing box face(0.05mm) Solid shafts are critical for pump reliability Eliminate sleeve runout Improved stiffness

36. SHAFT DEFLECTION

37. Shaft Whip

38. PUMP FAILURE ANALYSIS 6 month period in a typical process plant

39. OPTIMUM PUMP DESIGN OBJECT: Create a better environment and greater stability for the dynamic pump components (seals and bearings) ….to withstand the damaging forces inflicted upon them

46. LD PUMPS REDUCE BEARING LOADS

47. LD PUMPS REDUCE BEARING LOADS (Metric)

48. MAXIMUM STIFFNESS RATIO L3 / D4 RATIO Less than 60 (Inch) Less than 2.4 (Metric)

52. ALIGNMENT EVERY TIME A PUMP IS TORN DOWN, THE MOTOR SHAFT AND PUMP SHAFT MUST BE REALIGNED UNPROFESSIONAL OPTION TO RE-ALIGN …USE A STRAIGHT EDGE PROFESSIONAL OPTION IS TO USE DIAL INDICATORSTO MINIMIZE TOTAL RUNOUT MODERN METHOD IS LASER ALIGNMENT WHICH IS VERY ACCURATE

53. PRESENT ALIGNMENT METHODS WEAKNESSES All provide precision initial alignment Degree of accuracy varies Cost of system, training, and time involved in their use is dramatic Time consuming (possibly 2 workers, 4-8 hrs.) Difficult to compensate for high temperature applications Requires worker skill, dexterity, and training to achieve accurate results After pump startup, cannot insure continued alignment due to temperature, pipe strain, cavitation, water hammer, and vibration

54. MOTOR ADAPTER - WHAT IS IT? Machined component that connects a pump power end to “C” face (D flg.) motor thru close tolerance fits on each end Not a new technology Used on machine tools and gear boxes Operate with highest level of accuracy and precision Mechanical seal in a pump is a high precision component Mechanical seal accounts for 75% of pump downtime

55. MOTOR ADAPTER- ADVANTAGES Provides easy, accurate, and reliable alignment during operation Maintains near -laser alignment accuracy despite pipe strain, cavitation, high temperature, and vibration A device that reduces vibration will prolong seal life and increase pump reliability Reduces labor hours for initial installation During teardown, maintenance cycle time is reduced dramatically vertical mounting capability

56. MOTOR ADAPTER ADVANTAGES cont. High temperature applications Motor grows with the pump More even temperature gradient across the pump and motor assembly For high speed (3000/3600 RPM) applications - Alignment more critical Disadvantages Not as accurate as initial laser alignment due to inherent tolerance stackup of the various components

57. SEAL CHAMBERS

58. ELIMINATING SHAFT SLEEVES Add no stiffness to shaft Runout tolerance between shaft and sleeve compounds motion of seal faces in addition to deflection and shaft runout already present Deflection must be a maximum of .002” at the seal faces, yet faces are lapped within 2 helium light bands Deflection or motion at seal faces is 1000 times greater than the face flatness Sleeves are necessary for packed pumps, but with today’s new seals they serve no purpose

59. BEARING OIL SEALS Three basic types: Lip seal Inexpensive, simple to install, very effective when new Elastomeric construction Contact shaft and contributes to friction drag and temp. rise in bearing area After 2000-3000 hours, no longer provide effective barrier against contamination Will groove shaft

60. BEARING OIL SEALS cont. Labyrinth seals Required by API 610 Non-contacting and non-wearing Unlimited life Effective for most types of contaminants Do not keep heavy moisture or corrosive vapors from entering the bearing frame (especially in static state)

61. BEARING OIL SEALS cont. Face seals and magnetic seals Protect bearings from possible immersion Good for moisture laden environment Expansion chamber should be used to accommodate changes in internal pressure and vapor volume completely enclosed system (can be submerged) Generate heat Limited life

62. SYSTEM ONE LABYRINTH SEAL

63. BEARING LIFE Bearing life calculations assume proper lubrication and an environment that protects the bearing from contamination The basic dynamic load rating “C” is the bearing load that will give a rating life of 1 million revolutions L10 Basic Rating Life is life that 90% of group of brgs. will exceed ( millions of rev’s or hrs. operation) “Rating Life varies inversely as the cube of the applied load Reduction of impeller dia. from maximum improves life calculation by the inverse ratio of the impeller diameters to the 6th power

68. ANGULAR CONTACT BEARINGS Used as thrust bearing in pairs (also carry radial load) Mounted back to back (letters to letters) Provides maximum stiffness to shaft Avoid ball skidding under light loads Small preload eliminates potential Line to line design clearances Shaft fit provides preload Eliminates shaft end play Greater thrust capacity Required by API 610 Specification

69. BEARING PRELOAD Pump radial bearings have positive internal clearance Thrust bearings can be either positive or negative clearance ( 5310 vs. 7310 pr.) Preload occurs when there is a negative clearance in the bearing Desirable to increase running accuracy Enhances stiffness Reduces running noise Provides a longer service life under proper applications

70. BEARING CLEARANCES / PRELOAD

71. MICROMETER IMPELLER ADJUSTMENT Micrometer adjusting nut allows impeller to be set to precise clearance from the front of the casing Each line on the adjusting nut is a .003” (.08mm) graduation for axial movement of the shaft Normal setting is .015” (.38mm) from the casing face For every 50 deg. above 100 deg. fluid temp... add .002” clearance

73. OPTIMUM PUMP DESIGN SUMMARY Low L3D4 ratio as possible Solid shaft ( no sleeves) Large bore seal chamber Large oil capacity bearing housing Angular contact thrust bearings Retainer cover to hold thrust bearing (no snap rings) Fin tube cooling for bearing housing Labyrinth seals Positive / precision shaft adjustment method Investment cast impellers Magnetic drain plugs in oil sump “C” Frame motor adapter Centerline support for hot applications

74. REQUIREMENTS FOR PROPER EMISSION CONTROL AND MAXIMUM SEAL LIFE Shaft runout at impeller within .001” T.I.R. (.03mm) Coupling alignment within .005” T.I.R. on rim & face (.13mm) Operation of the pump at or close to best efficiency point (definition dependent upon pump size, speed, and LD ratio) NPSH available to be at least 5 feet (1.5m) greater than NPSH required Proper foundation and baseplate arrangement Absolute minimum pipe strain on suction and discharge flanges All impellers dynamically balanced to ISO G 6.3 spec. Face of seal chamber square to shaft within .002” T.I.R. (.05mm) Seal chamber register concentric to shaft within .003” T.I.R. (.08mm) Shaft end play less than .0005” (.015mm)

75. SYSTEM ONE PUMP WARRANTY

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