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1 st PUMP HANDS-ON MAINTENANCE AND RELIABILITY CONFERENCE Session 1: CENTRIFUGAL PUMPS ATLANTA, GA SEPTEMBER 22-23, 20

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1 st PUMP HANDS-ON MAINTENANCE AND RELIABILITY CONFERENCE Session 1: CENTRIFUGAL PUMPS ATLANTA, GA SEPTEMBER 22-23, 2005. Centrifugal pumps – Head generators Positive Displacement pumps – Flow generators. CENTRIFUGAL. Let’s Get to the Hardware!. PERFORMANCE CURVE - COMBINED. Max OD.

1 st PUMP HANDS-ON MAINTENANCE AND RELIABILITY CONFERENCE Session 1: CENTRIFUGAL PUMPS ATLANTA, GA SEPTEMBER 22-23, 20 - slide 1
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1 st PUMP HANDS-ON MAINTENANCE AND RELIABILITY CONFERENCE Session 1: CENTRIFUGAL PUMPS ATLANTA, GA SEPTEMBER 22-23, 20
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  1. 1st PUMP HANDS-ON MAINTENANCE AND RELIABILITY CONFERENCE Session 1: CENTRIFUGAL PUMPS ATLANTA, GA SEPTEMBER 22-23, 2005 Pumping Machinery, Pump School

  2. Centrifugal pumps – Headgenerators Positive Displacement pumps – Flow generators Pumping Machinery, Pump School

  3. CENTRIFUGAL Pumping Machinery, Pump School

  4. Let’s Get to the Hardware! Pumping Machinery, Pump School

  5. Pumping Machinery, Pump School

  6. PERFORMANCE CURVE - COMBINED Max OD NPSHR lines Efficiency lines BestEfficiencyPoint line MCSF line BHP lines Rated point Min. OD Pumping Machinery, Pump School

  7. AFFINITY LAWSWhat happens to Flow, Head and Power with Speed? Flow changes DIRECTLY (linear) with RPM… Head changes as a SQUARE of RPM… Power is proportional to Flow times Head – it changes as CUBE of RPM… Q ~ RPM H ~ RPM2 BHP ~ RPM3 Pumping Machinery, Pump School

  8. More Affinity Laws… When impeller OD is trimmed – Flow, Head and Power follow the Affinity Laws very similar to the case of speed change: ODold Q ~ x H ~ x2 BHP ~ x3 ODnew where x is a cut ratio: x = ODnew/ODold (Note: additional correction applies for cuts over 10%) Pumping Machinery, Pump School

  9. Let’s test some pumps! Pumping Machinery, Pump School

  10. a SYSTEM CURVE System Hydraulic Losses Friction (hf) hf ~ V2/2g Static (h0) Flow Pumping Machinery, Pump School

  11. Parallel Operation Head Flow 500 500x2 = 1000 Pumping Machinery, Pump School

  12. “Double the pumps” - But will Flow Double for sure?! Pumping Machinery, Pump School

  13. It depends on a System! 1000 ft (static head) … long pipe, elbows, valves – a lot of friction… Case B Case A Pumping Machinery, Pump School

  14. Case A – mostly static head Head, ft h0 = 1000 ft Flow, gpm 500 500x2 = 1000 Pumping Machinery, Pump School

  15. Case B – mostly friction If the system can not handle it – more pumps will not add any more flow! Head, ft Flow, gpm 1000 500 550 !? Pumping Machinery, Pump School

  16. SUCTION CHARACTERISTICSCAVITATION, NPSH Basically, if there is not enough pressure – liquid boils! Pumping Machinery, Pump School

  17. In your kitchen, the water boils at 100 oC (212 o F) – and that is at atmospheric pressure If pressure drops, the water will boil at lower pressure On top of high mountain water boils at perhaps 95 oC ? Pumping Machinery, Pump School

  18. NPSH DEFINITION NPSHA = available NPSHR = required NPSHA is a total available suction pressure - over the vapor pressure - (expressed in feet of head). In other words, it is Net Suction Head minus vapor pressure (expressed as head) NPSHA is NOT simply the level of liquid in the suction tank… Pumping Machinery, Pump School

  19. A lot of bubbles… More bubbles… Incipient Head, ft 3% NPSHR3% NPSHA, ft Pumping Machinery, Pump School

  20. NPSHR With suction pressure dropping, a point may be reached that liquid starts to transform into vapor somewhere inside the pump. This is not good. But how bad is bad? Hydraulic Institute define the NPSHrequired as such value of NPSHR when a pump losses 3% of its developed head. They call this NPSHR3% For simplicity, they just write it as NPSHR, implying 3% Pumping Machinery, Pump School

  21. CAVITATION DAMAGE Too many candies makes kids hyper. But it also ruins their teeth. Pumping Machinery, Pump School

  22. Impeller inlet – blades cavitation on a suction side As bubbles flow from low pressure to higher, they implode against metal surfaces. These micro-hammer-like impacts erode the material, creating cavities – thus “cavitation” Pumping Machinery, Pump School

  23. Good ways to fight suction problems: • Make sure a pump is as close to suction source as possible • For double-suction pumps, suction valve stem should be oriented for symmetrical feed flow • Smaller eye impeller (lower suction specific speed) can help • Inlet sump design – critical: vortexing and air entrapment could be a nightmare • Metallurgy – 316ss stainless work-hardens, while iron does not very long Pumping Machinery, Pump School

  24. SEALING METHODS • PACKINGS: inexpensive, but - 10 drops per minute • MECHANICAL SEALS: most popular, 10 “drops” per day • SEAL-LESS: more expensive, but - zero leak • CANNED MOTORS • MAG-DRIVES Pumping Machinery, Pump School

  25. PACKINGS(courtesy Durametallic Seal Manual) Packed Box Pumping Machinery, Pump School

  26. MECHANICAL SEALS • SINGLE • INSIDE • OUTSIDE • MULTIPLE • Unbalanced, balanced, single-spring, multiple-spring, pusher, non-pusher, variety of elastomers, face materials, and hardware materials. • Variety of flush plans. Pumping Machinery, Pump School

  27. Single Mechanical Seal, multiple springs, unbalanced (Courtesy Durametallic) Pumping Machinery, Pump School

  28. Double Mechanical Seal, multiple springs, unbalanced (Courtesy Durametallic) Pumping Machinery, Pump School

  29. (Courtesy Durametallic) Pumping Machinery, Pump School

  30. (Courtesy Durametallic) Pumping Machinery, Pump School

  31. MAG-DRIVE PUMPS(Courtesy of Goulds Pumps) Pumping Machinery, Pump School

  32. Pumps and Systems Reliability Pumping Machinery, Pump School

  33. Horizontal Offset Horizontal Angularity (Yaw) Motor Motor Pump/Fan/Gearbox/Etc. Pump/Fan/Gearbox/Etc. Vertical Angularity (Pitch) Vertical Offset Motor Motor Pump/Fan/Gearbox/Etc. Pump/Fan/Gearbox/Etc. Types of Misalignment Pumping Machinery, Pump School

  34. 250% 200% Water in Oil (ppm) 150% 100% 50% 0% 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Rated Bearing Life Based on 100% life at 100 ppm water Effect of Water on Bearing Life One PPM is one milligram per kilogram. Pumping Machinery, Pump School

  35. Pump-to-Piping Alignment Step 1: Pre-installation stage (pump may not have even arrived to site yet) – anchor the main piping properly. Leave room for the final spool pieces (to be made later) by the pump. Pumping Machinery, Pump School

  36. Step 2: Rough alignment phase. Pump has arrived. Position it and make spool pieces. Pumping Machinery, Pump School

  37. Step 3: Remove all equipment. Level the baseplate to 0.025” from end to end. Clean up and get ready for the grouting. Pumping Machinery, Pump School

  38. Step 4: Grouting phase. Pumping Machinery, Pump School

  39. Step 5: Reinstall the pump and a motor on a baseplate. Inspect and make sure nothing is binding up. Pumping Machinery, Pump School

  40. Step 6: Rough align pump to a motor. Pumping Machinery, Pump School

  41. Step 7: Make up final spool pieces. Pumping Machinery, Pump School

  42. Step 8: Install the spool pieces between piping and a pump. Leave gaps (1/16” – 1/8”) for the gaskets. This gap is the only distance the piping will be pulled during final bolting, and stresses will be minimal. (The pump will thank you for that). Pumping Machinery, Pump School

  43. Step 9: Final alignment of a motor to pump. Pumping Machinery, Pump School

  44. Step 10: Final piping verification. Unbolt the pump from the driver. Loosen up piping bolts and retighten. Indicator should not move more then 0.002”. Otherwise modify, adjust or remake spool pieces. Pumping Machinery, Pump School

  45. Pumps Troubleshooting • Startups • Troubleshooting • Repair and Overhaul Note of acknowledgmentisdueto my friend Mr.. JimBrennanof IMO/Colfax, and his excellent articles on pumps startup, troubleshooting and overhaul, published in Pumps & Systems magazine over the years. Jim has over 30 years experience in the pump industry, and is active in various pump committees and organizations. Much of this information was based on his recommendations, as well as our numerous and continued discussions and friendly debates over the years. Pumping Machinery, Pump School

  46. Startups • Most vulnerable time for pumps • Read technical manuals and instructions thoroughly • Pump • Driver • Auxiliaries • Review piping and valving first • Backwards? • Absent? • No weld beads, no weld rods, no scale • Temporarily strainers • Permanent strainers • Clean start conditions Pumping Machinery, Pump School

  47. Startups – cont. • Was piping pressure tested? Design limits observed? • Low pressure air to find gasket leaks • Check and tighten flange bolts to correct values • Is inlet piping straight for long enough distance? • Is piping adequately supported? Is your pump condemned to be an anchor? • Pressure relief valves present? • Entire system should be flushed – by a temporarily pump • At least 24 hours • Higher flow rates to dislodge junk • Some junk may remain for 30 days or more • “Pigs” sometimes use to get pipes clean Pumping Machinery, Pump School

  48. Startups – cont. • Make sure valves that should be open – are open • Make sure valves that should be closed – are closed • Air bleed installed at high point? • Observe, and exercise caution • Foundation, Alignment and Rotation • Level and clean • Hold-down bolts tight • Cold or Hot alignment • Dowelled in-place? • Direction of rotation? Pumping Machinery, Pump School

  49. Startups – cont. • Lubrication – is everything greased or oiled? • A person should be able to turn over almost all pumps by hand • Startup spares • Elastomers and gaskets • Bearings • Seals • Critical parts • Pressure gages – without them you are working blind • How will you verify flow? • Speed tachometer • Temperature Pumping Machinery, Pump School

  50. Startups – cont. • Fill the pump and inlet piping as much as possible • Do not run dry • Have safety phone numbers on hand: key vendors, medical, fire, etc. • Err on a safe side Pumping Machinery, Pump School