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  • 1.  Centrifugal Pump Performance Maintenance Testing

    Posted 10-16-2018 07:10 AM

    Conducting reliability testing to verify pump performance as a way to measure performance against shut off pressures to get better information on when a pump should be taken out of service for rebuild before it actually fails for scheduling pump rebuilds. My question is how are other Municipalities doing this in Water, Reclaimed or Wastewater?  We use PdM Vibration reports for bearing checks, but to verify wear rings and impeller clearances what are best practices on this maintenance to verify pump performance?

     

    Thank You,

    Dean G. DelGrosso

    Assistant Section Manager

    Public Utilities Department


    P:  (813)-663-3200

    C:  (813)-712-0151

    M: (727)-359-2739

    E:  delgrossod@HCFLGov.net

    W: HCFLGov.net

     


    Hillsborough County

    334 N Falkenburg Road, Tampa, FL 33619
     


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    Please note: All correspondence to or from this office is subject to Florida's Public Records law.

     



  • 2.  RE: Centrifugal Pump Performance Maintenance Testing

    Posted 10-17-2018 08:20 AM
    We've used thermodynamic efficiency testing (a.k.a. Yates Meter) on our filtered water pumps to good effect here. The test is fairly easy to do (maybe a little harder to analyse, as we had to track down some original pump curves) and yields an efficiency result that makes it fairly straightforward for deciding which pumps to open up for inspections. In most cases the causes of the lower efficiencies were impeller clearances and wear ring wear that you are interested in.
    We've also noticed that issues with wear rings seem to show up as increased thrust bearing temperatures caused by the imbalance of flow around the impeller causing an axial shift of the shaft. In many cases technicians would install fans or cooling lines on bearing housings that worked fine for years on their own. After some discussions we ended up inspecting many of these "hot bearing" pumps and found wear ring issues.
    Hope that helps.

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    Peter Lewis
    Senior Engineer
    City of Toronto, Toronto Water
    Toronto ON
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    Original Message


  • 3.  RE: Centrifugal Pump Performance Maintenance Testing

    Posted 10-17-2018 08:42 AM

    Dean,

     

    On our larger pumps we use the process instrumentation available such as head pressure, discharge pressure, discharge flow, motor power (or amps), and motor speed (if on VFD) to calculate a "performance" value that is akin to pump efficiency.  This is done in our historian (PI) but could easily be done in SCADA.  When trended over time, this value can show a loss of performance due to wear, damage, etc.  Part of our condition monitoring is to regularly evaluate these trends and help make a decision on when a rebuild is warranted.  This also works well on some of our progressive cavity pumps to gauge stator wear.

     

    The formula used depends on the instrumentation data available and pump curves.  Some manufacturers publish a pump specific efficiency calculation, which is a great starting point, but may need to be tweaked depending on the data available.

     

    I hope this helps.

     

    Ken Betts

    Maintenance Planner

    Metro Wastewater Reclamation District




    Original Message


  • 4.  RE: Centrifugal Pump Performance Maintenance Testing

    Posted 10-20-2018 02:18 PM
    Hi everyone; In my opinion, the CBM/PdM techniques is not the best way to identify when the Pumps needs an overhaul (internal parts). I send you some links with readings that can clarify the point:

    Full-Scale Diagnostic/Prognostics of Pumps - Empowering Pumps and Equipment
    Empowering Pumps and Equipment remove preview
    Full-Scale Diagnostic/Prognostics of Pumps - Empowering Pumps and Equipment
    Author: Ernesto Primera This article is intended to show the importance of watching over the health of a pump from different perspectives; by "health" meaning the range between the ability and inability to accomplish its primary and secondary functions within a specific context and work environment, with previously established limits, and with a previously defined mission.
    View this on Empowering Pumps and Equipment >


    ------------------------------
    Ernesto Primera SME
    Senior Machinery Reliability Eng.
    ASME Global Instructor & Speaker Bureau
    Alabama - USA.
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    Original Message


  • 5.  RE: Centrifugal Pump Performance Maintenance Testing

    Posted 10-25-2018 06:18 AM
    Typical sensor arrangement for Pump performance monitoring
    The above is a typical sensor measurement system arrangement to help you put together a comprehensive pump performance monitoring program. 

    Pump Efficiency is calculated using ASME PTC 8.2 (Pump efficiency, head and corrected head). Pump head (Design) is calculated from the pump characteristic curve. 

    Our team will work with you to perform the necessary project and site scoping activities to define the hardware required, including any new recommended instrumentation and wireless infrastructure. While wireless devices provide an easy means of adding missing measurements, Plantweb Performance Advisor solutions can make use of existing wired or wireless measurements too, provided the minimum instrumentation requirement is met.

    The Plantweb Performance Advisor models run on an OSIsoft PI Asset Framework (AF) server. The application can be easily integrated
    with other existing plant historians (IP21, <g class="gr_ gr_193 gr-alert gr_gramm gr_inline_cards gr_run_anim Punctuation multiReplace" id="193" data-gr-id="193">PHD</g>, etc.) through data connectivity solutions from OSIsoft.

    I can help you connect to an Expert in your world area to ensure that your problem is solved. Happy Pumping!

    ------------------------------
    Vinay Maithani
    Reliability Consultant
    Emerson
    Abu Dhabi
    ------------------------------

    Original Message


  • 6.  RE: Centrifugal Pump Performance Maintenance Testing

    Posted 10-25-2018 01:25 PM
    ​The increase in wear ring and/or impeller clearances means reduction in efficiency and increase in temperature of fluid. You may see reduction in flow and increase in head and temperature of fluid. So as per API if the flow is outside the allowable region that is 70% of BEP (best efficiency point) there will be high vibrations, reduction in NPSH that could lead to knocking due to cavitation. So , measure flow that should be > 70% of BEP otherwise there is leakage, increased internal clearances, obstruction in suction or less flow.

    ------------------------------
    Vinod Kumar
    Manager, AMS
    SKF
    Calagry, AB
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    Original Message


  • 7.  RE: Centrifugal Pump Performance Maintenance Testing

    Posted 10-31-2018 11:18 AM
    ​Looks like some good responses to your question.

    The pump performance will obviously change with wear ring wear leading to lower pump head, higher flow, higher HP, increase in temperature fluid temp, increased vibration, etc. so which is used to trigger a rebuild?  I think it comes down to what is your financial break point for operating an inefficient pump.  If the pump will not provide full system function when wear is at a certain point then the decision is based on some process/system parameters.  A pump may operate and function in a system even when the wear rings are worn beyond recommended clearance but wasted energy is the price.  You will have to justify a pump rebuild with some level of company ROI to pull the trigger on pump maintenance. 

    I would track pump pressures, flow, and especially BHP and then when a rebuild is done document that compared to your clearances.  A financial calculation would need to be done based on that to determine where a feasible point is to perform a pump rebuild/replacement.
    After modeling this some, it may be a fairly predictable model to do a rebuild on time as well.

    I work in a process plant and most of our process pumps are rebuilt on condition based monitoring of being able to support the process function of the pump system in regards to pump wear, impeller clearances, etc.



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    Randy Riddell, CMRP, PSAP, CLS
    Reliability Manager
    Essity
    Cherokee AL
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    Original Message


  • 8.  RE: Centrifugal Pump Performance Maintenance Testing

    Posted 11-01-2018 08:52 AM
    ​I've worked with process pumps in the past and used all of the methods mentioned by other members. I'd like to mention an additional option to consider.

    The US Department of Energy has a Pumping System Assessment Tool application. It's available on the DOE's Advanced Manufacturing landing page. The software is free and runs on Win 7, although I'm not sure if it will run on Win 10 systems.

    Based on Hydraulic Institute standards, the PSAT program has a not-so-easy to use interface, but outputs reliable prime mover and pump efficiency. I've used it for a couple of large process pumping systems to validate data collected from SCADA.

    DOE also offers a collection of software tools for assessing steam, fan, process heating, and compressed air. All are free, and reliable analysis tools for industry.


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    Steven Thompson
    CEM, CEA, SMRP
    Nissan North America
    Canton MS
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    Original Message