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  1. jet1749

    Small pump for liquid pentane

    What about using a regenerative turbine pump? I've used them in chemical plants, they're ideal for high head very low flow applications. I've used them down to 0.5m3hr flowrates. I think Sundyne market them under the Caster brand.
  2. jet1749

    Do splicing o-ring's affect properties.

    Hi, Ive spliced orings in static applications using superglue as an adhesive. Also bind the finished spliced joint with ptfe thread tape to isolate the process medium from the joint. regards John
  3. jet1749

    vibration signature - slot filled bearing

    Tmoose Double row angular contact bearings with filling slots are very common. They are a high load capacity bearing but only in one direction. You have to be sure of the direction of thrust in order to take advantage of it. I have changed out this type of bearing on some other pumps...
  4. jet1749

    vibration signature - slot filled bearing

    Thanks for the replies, The impeller has 5 vanes. Vibes were strongest at the drive end and were actually audible. Reversing the orientation of the double row angular contact bearing cured the problem (thrust forces had been running against the filling slot, but no actual visible damage when...
  5. jet1749

    vibration signature - slot filled bearing

    Hi, I'm a vibration amateur, so hopefully someone can advise. The problem was high vibes at 14X running speed on a recently overhauled centrifugal pump. Vibes were at the drive end, which is fitted with a slot filled double row angular contact bearing. The pump runs at 3000rpm Vibes were at 14X...
  6. jet1749

    Recirculation

    I think he refers to recirculation within and around the impeller vanes due to operating at low flow or high flow conditions. This is due to the impeller vane angles being designed around a flow rate envelope. Operating outside of these flowrates produces a stall condition similar to that...
  7. jet1749

    METAL IMPELLER PUMP VERSUS POLYMER IMPELLER PUMP

    Hi, i've used Warman 3/2 CAH rubber lined pumps with rubber lined impellers successfully on Water with Sodium Thiocyanate and Volcanic Ash duty. One thing to bear in mind when using rubber lined impellers is that they can't be trimmed. So will require either a belt drive or vfd to achieve duty...
  8. jet1749

    Part failure - need help figuring out why - Stress Concentration

    Fracture face analysis would surely explain the mode of failure and its origin regards John
  9. jet1749

    odd marks on journals / bearings

    Longitudinal marks on journal look very much like grinding wheel marking, possibly from "blinded" wheel or excessive load applied to wheel. Has the journal been refinished at some point? regards John
  10. jet1749

    Fault in progressive cavity pump

    Hi, had a similar problem pumping vacuum degassed acrylic dope at 40,000Cp using Mono PC pumps. Turned out it was the mechanical seal allowing ingress of air. Had to alter pipe work so suction became discharge and change pump rotation. Net effect was that mech seal was then at high pressure end...
  11. jet1749

    Mag drive pump behaving inconsistently

    Seen this kind of thing before on magdrives, several answers listed already. My experience included reduced magnetism due to the use of stainless steel containment cans. Low flow conditions leading to high temperature at the inner magnetic rotor (below a certain temperature the magnetic strength...
  12. jet1749

    OB thrust bearings discolouring oil

    Hi, had similar recent problems on recently overhauled David Brown multistage crude oil charge pumps. Problem seems to be skidding row of balls in double row angular contact bearing and also wear of the pressed steel bearing cage (SKF Explorer bearing)See this article for more explanation...
  13. jet1749

    impeller nuts coming off

    Sounds like vibration loosening the nut off, especially if the shaft subsequently snapped at the thread relief. Any cavitation or out of balance? try a vibe check whilst the pumps are running.
  14. jet1749

    Acceptable m/seal leakage rates?

    Our operators are requesting guidance on acceptable mechanical seal leakage rates (I know this seems a contradiction in terms!)Typically interested in API hydrocarbon pumps. I am aware that this has implications with COMAH DSEAR and environmental considerations etc. But one mans drip is another...
  15. jet1749

    API MTBF

    Plenty of food for thought from the replies. We are presently around the 44 month mark. Our problem is that we cannot compare with other refineries in our group because they use different criteria. We count failures as direct interventions caused because the pump fails to function as designed...
  16. jet1749

    API MTBF

    Hi, anyone got average industry standards for pump MTBF for API refinery pumps, with source or reference. Need to know how well we are doing!! best regards John
  17. jet1749

    Dual seal barrier fluid for hydrofluoric acid environment

    Using Total Seriola 22 heat transfer oil at the moment but not entirely happy with it. I am also considering using Alkylate
  18. jet1749

    Two stage pump and L3/D4

    Thanks for the replies. Just to add a little more information, the pump is a 1960's vintage pump on hot hydrocarbon service. Approximate dimension between NDE bearing and mid-point of outboard impeller is 20" the shaft diameter under the seal sleeve is approximately 2" giving L3/D4 of 500 which...
  19. jet1749

    Two stage pump and L3/D4

    I have a Hayward Tyler 2 stage end suction overhung centrifugal pump suffering from mechanical seal and thrust bearing problems. The outboard end of the shaft is supported in a steady bush inside the pump case (similar to a wear ring)operating speed is 2950rpm. Can the stiffness of the shaft of...
  20. jet1749

    NPSH REQUIRED Relationship to Impeller Diameter

    What Yorkman suggests is basically how you perform an NPSHr test Pick a couple of points on the performance curve. Run pump at constant speed, vary the suction pressure whilst trying to maintain constant head and flow at the selected point. Where head reduces by 3% that is your NPSHr at that...

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