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  1. eduvillela

    clearance between shaft and shaft hub

    hello all! Can a high clearance between the shaft and the shaft hub lead to high vibration levels? And does it appear in the espectrum as 1x only ? thank you in advance!
  2. eduvillela

    Pumps shaft alignment and vibrations

    When the two shafts are not aligned, it's quite common to see the n and its harmonics, mainly 2n and 3n frequencies in the spectrum. Take a look at this simple article here: http://www.plantservices.com/articles/2014/vibration-analysis-detect-alignment-problems/
  3. eduvillela

    FLOW ELEMENT (Differential Pressure)

    I must agree with you when you say (P1-P2) = Diff. Pressure or Pressure Loss I don't see why these two definitions would be different. Static pressure is defined as the pressure measured by pressure gauges. The Total pressure is the sum of Static pressure and the velocity pressure. But in the...
  4. eduvillela

    leakage through the seal

    I see your point EdStainless. I've studied more the issue and I think letting the rubber lips run over a shaft sleeve will be the best and cheapest solution. And at any time the sleeve gets worn out it can be replaceable. Thank you
  5. eduvillela

    real pump curve

    Hello All Let's suppose I've got in hands the pump theoretical curve (given by the Euler equation) and the efficiency pump curve. Can I estimate the real pump curve simply by multiplying the theoretical curve by the efficiency at any flow point? Thank you in advance
  6. eduvillela

    leakage through the seal

    There are no suspended solids in the system. It's simply water. Perhaps a hard sleeve o-ringed might solve the problem, and it´s a pretty simple solution. Another solution I've been thinking about is nitriding the shaft surface. So the hardness increases and the excessive wearing stops.
  7. eduvillela

    shaft material

    Hello! The company I work designs water pumps. The water (usually at 104 ºF) is sealed by a rubber sealing. The problem is that within short amounts of time of running the shaft gets worn by the action of the rubber lips. The shaft material is AISI 304. I think it's not hard enough to...
  8. eduvillela

    High vibration uncoupled motor. Broken or Cracked Rotor?

    Sidebands indicates amplitude modulation, and by the spectrums you attached here, it seems that the frequency modulating the harmonics is abtou 250 CPM, which appears with a little peak on all the spectrum. The point is to find out what problem is generating this frequency. But by taking all...
  9. eduvillela

    rubber seal leakage

    Hello, Here in my company we design and manufacture small pumps, among other equipments. But we're having troubles with the pump sealing. After one year of running, the fluid (usually water - 86°F) starts to leak through the rubber seal. After disassembling the pump to fix the problem, we find...
  10. eduvillela

    Selecting the fire pump

    first thing to do is to determine the specific speed, so you can select the best pump to your application. Here you can find how to calculate that: http://www.engineeringtoolbox.com/specific-speed-pump-fan-d_637.html
  11. eduvillela

    Calculate pressure after an orifice

    If both orifices are in series, then certainly the flow rate must be the same through both. Unless there's leakage..
  12. eduvillela

    leakage through the seal

    Hello, Here in my company we design and manufacture small pumps, among other equipments. But we're having troubles with the pump sealing. After one year of running, the fluid (usually water - 86°F) starts to leak through the rubber seal. After disassembling the pump to fix the problem, we find...
  13. eduvillela

    Finding NPSHr - Varying Pump Height

    Hello, justomi let me ask a few questions first. How excaclty do you measure the TDH? Are there pressure gauges? I'm asking that because I didnt notice them at your sketch. By raising the pump, you end up changing the pump line geometry, and hence you cannot calculate the head loss at suction...

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