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Recent content by tstead

  1. tstead

    MEASUREMENT & ESTIMATION OF PUMP FLOW

    You measured flow by two different methods and arrived at essentially the same value. I would therefore suspect your power reading. A couple thoughts, though...how did you compute input power? Did you take into account the motor's power factor or the effects of three-phase power? Tim
  2. tstead

    VIBRATION LIMITS IN DRY WELL SUBMERSIBLE SEWAGE PUMPS

    You, as the end user, cannot reliably balance a single vane impeller as you would any other impeller. Single vane impellers must be balanced, essentially, by an analysis of the forces acting on the impeller at the intended duty point and is done by the manufacturer. Tim
  3. tstead

    VIBRATING SEWAGE PUMP

    Do you have a single vane sewage pump impeller? Who is the pump mfgr and what model is it? Tim
  4. tstead

    Pressure-Relieving Flange Gasket??

    RMW, You might have solved the conumdrum! Tim
  5. tstead

    continuous shutdown of a pump [b]

    Daniel, Your major concern with repeated starts and stops is with the motor because each start heats up the motor just a little more than usual. Make sure you keep the starts/hour within the motor mfgr's recommendation. Of course, other issues abound like what friar mentioned. For example...
  6. tstead

    Mechanical Seals

    Paul, Are you sure the piping arrangement is not an internal relief line? The problem with running an unbalanced seal at higher pressures is also that it generates more heat at higher pressures because not only do you have spring force pressing the faces together but you also have suction...
  7. tstead

    Coupling bore/keyway size

    Regardless of the existance of a "rule of thumb" you need to contact the coupling mfgr for their recommendation just as Artisi said. Don't guess. If it's worth doing, its worth doing RIGHT. Tim S.
  8. tstead

    Pressure-Relieving Flange Gasket??

    Art, I had to scratch my head also. My guess is that a "pressure-relieving flange gasket" is a name that some shady gasket company came up with for an inferior product. If you want pressure relief in a piping system, you MUST MUST MUST MUST MUST install some sort of pressure relief valve...
  9. tstead

    To seal or not to seal We are in

    RHC, What you need is a double mechanical seal with a buffer fluid between the two seals at a slightly higher pressure than the pressure in the seal chamber such that the buffer fluid leaks into your pump. This assumes, of course, that your process fluid can accept dillution. Like always...
  10. tstead

    how to determine a pump's head and flow by examining the impeller?

    Why not just test the pump and take all the guesswork out of it? Tim S.
  11. tstead

    pump material

    FRP. Tim
  12. tstead

    Pump Recycle Control

    Why is VFD not an option? You have a tremendous swing of pressures that the pump must operate against - 23 to 231 feet of head - give or take. That is asking quite a bit from a constant speed centrifugal pump. So why is a VFD not a feasible option? Tim
  13. tstead

    radial clearance in bearing

    Have you tried to contact the bearing manufacturer (SKF) directly? KSB uses SKF ball bearings in their pumps (some KSB factories may use FAG bearings). Also, the bearing number you provided indicates that it is a single row bearing. Be certain this is correct and that either bearing isn't a...
  14. tstead

    Can BUMP starting a Centrifugal pump cause wear ring melting together?

    Ayden, Bump starting is common place to ensure that the pump is rotating in the proper direction. Also, if motor amp data is taken during the bump starts then do yourself a favor. Throw that data in the trash because it is essentially worthless. Tim
  15. tstead

    Can Pumps Operate Below Shutoff Head?

    Patricia, The pump vendor will furnish the minimum flow. There are a few things that go into this determination. One is limiting the heat rise of the fluid, another is maintaining seal integrity, and another is preventing pump damage (e.g. shaft damage). The minimum flow is essentially the...
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