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Recent content by DubMac

  1. DubMac

    good day, I am a marine engineer

    Good day to you sir. It is a bit late in the evening for me and not able to provide full comment, but I would first ask why you have mechanical seals on this pump at all. On a water service? I would much prefer packing which is more durable and much cheaper to replace. With a good water flush...
  2. DubMac

    Dewatering pump options - approx 120 m LIFT

    Aha...yes a bit clearer picture. A PC pump would be a great choice; probably would require a couple of them in parallel to make the flow requirement. Mono had a proprietary design using a "flexi-shaft"; a very clever option to get away from the geared universal joints that commonly plague most...
  3. DubMac

    Dewatering pump options - approx 120 m LIFT

    Ha ha! Excellent point MH. Before my original post, my first thought was to clarify exactly your point; ain't nobody liftin' water 120 meters. However, technical language has become so sloppy these days. I supposed Pumpingtips had supposed the pump located at -120 meter grade level. If the pump...
  4. DubMac

    Dewatering pump options - approx 120 m LIFT

    Keep in mind that wear increases as the cube of the speed increase, so if there are ANY solids in this mix, you want to be careful with a 2 pole. You might look at a two stage splitcase. As Artisi is indicating, Sulzer is probably overkill here as their expertise is in process/API pumps, not...
  5. DubMac

    Pump overload

    Remember that the equations for viscosity correction apply to CENTRIFUGAL pumps only. For your gear pump, the best information you will get is from the manufacturer. They should have empirical data on how their pumps perform with various viscosities. Also recall that not only the pump but all...
  6. DubMac

    Net Positive Suction head NPSH

    Incomprehensible.
  7. DubMac

    Pump Maximum Flow Rate

    Looks like a self-priming pump. Just a thought.... if this is on a lift operation, your flow will be VERY dependent upon the amount of lift you are trying to achieve.
  8. DubMac

    What kind of tests for bare pump?

    Depends on what you are using the pump for. A simple water pump used to occasionally fill a tank would not require anything near what a multistage boiler feed pump would require. Hydrostatic tests are always performed by the manufacturer whether you want it or not. Most manufacturers run a...
  9. DubMac

    NPSH for HP/IP combine pumps

    physics
  10. DubMac

    Centrifugal pump intermittent high amperage issue

    The first thing I would do is Google "viscosity correction for centrifugal pumps" and use the correction factor based upon your viscosity to replot the performance curve. You might be surprised at how much performance is affected by just a slight uptick in viscosity. If viscosity is the...
  11. DubMac

    Oversizing pumps and motors

    Probably the most common root cause of pump problems is having had too much, or too many safety margins applied to design flow and/or head. Engineers have been making this ridiculous mistake for so long and so often that they must be in cahoots with the Aftermarket Services groups. I always...
  12. DubMac

    pump performance

    If I recall rightly, a vortex breaker's purpose is not to "straighten" the flow profile into the suction case, it is a device used in the sump or the tank to prevent vortexes forming on the surface and drawing air bubbles down into the suction line and creating havoc when the bubbles...
  13. DubMac

    Vertical mixed flow turbine pump selection

    No doubt, from performance, to maintenance familiarity, to spares issues, use the same pump! However, you asked for broad information and gave very limited information; hope you are more thorough when actually buying this pump. If a duplicate is not available or the user is not satisfied with...
  14. DubMac

    PD pump vibration transmitted to rack

    Failing a bladder type damper solution, you might look at mounting the pumps on wire rope isolators. If sized properly these can dissipate a good portion of the vibration by converting it into heat as the strands rub against each other. Much of the discharge piping on high-end frac trucks has...
  15. DubMac

    Help With Pump Identification

    The 3 largest makers of splitcase fire pumps in the past have been: Aurora, Peerless, and Patterson. Looks most like a Peerless to me. That 2nd pic with the gussets welded on the bonnet are kinda strange. I don't ever recall seeing any of those. Makes me think it is either after the fact add-on...
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