Solving the 10 Most Common Problems with Self Priming Pumps (Part 1 of 2)

PROBLEM SOLVING:

SELF PRIMING PUMPS

In this article we’re going to tackle four of the biggest issues that people have with self priming pumps.

  • No flow,
  • Low flow/pressure,
  • Noise and Vibration,
  • Increased/ high maintenance
  • Table of Content

    Is your self priming pump primed

    Despite it being a self priming pump you still need to initially fill up the pump casing with liquid. This is allowed the air within a suction pipe to be displaced by the pump. It works by mixing air with recirculating liquid. The air is then separated from the liquid and is discharged from the case. Once all the air has been removed from the suction line it then pumps like any other centrifugal pump. Depending on the pump you have it is usually just easy to fill the pump casing through the priming cover.

    Self Priming Pump Filling Point

    Check for leaks or loose joints

    This is very crucial in the suction pipework. Leaks could either be at a joint or at the liquid source itself. Make sure that the suction pipework is completely submerged and that the joints are properly sealed and with gaskets where possible, this will prevent any air in training and subsequently ensure your pumps operate.

    But air can get in through many other means such as the mechanical seal and casing connections. It can be hard to spot an air leak in a suction pipework. A useful tip is to keep your suction pipe as short as possible and try to have as little connections as you can. If there’s a flat valve on the suction line you may be able to see water leak on pump stop. Or for some systems some soapy water may work, but there are numerous audio and visual methods to identify leaks.

    Is your motor speed quick enough?

    This is especially important for pumps if operating on variable speed.  If rotating at a low speed it may not be a suitable speed to allow your pumps to initially prime, in which case you will have to ensure that initially, when starting your pumps , it starts at it’s full speed capacity, before then reducing to the speed that you require. similarly a low rotation will result in a low flow and pressure. In which case, if you used to increase the speed of your pump you will expect an increase in flow and pressure.

    High suction lift

    Now the greatest thing about a self priming pump is its capability of doing a suction lift. All self priming pumps are issued with performance curves that shows for a given pressure you can expect a given flowrate. As a example lets imagine your pump initially works and then loses its prime and starts making noises while pumping down the well well. A reason for this is because the lower you pump your well down, the greater the height difference your pump needs to achieve if you could move your pump lower to the liquid source then this will help alternatively you could raise your liquids start stop levels.

    As most people know; the more system pressure (i.e the higher the pump has to lift) the smaller the pipe work is, or the more bends there are, then the less flow rate you’ll get. However, one thing that most people tend to miss is the NPSH curve.
    To explain NPSH (net positive suction head) read the following article: www.bepumps.co.uk/news

    Blockages and Clogging

    When pumping liquids with solids one of the biggest issues that people find is blockages. Blockages can usually be found in the suction pipe work, pump casing itself or in the discharge pipework. Typically you will find blockages in pipe work openings, around bends, in valves, pretty much anywhere in the pipework or pump casing. But the good thing about blockages are that they usually are easy to remove, either:

    All of these can be easily done, but the most important tip to reduce the chances of blockages is to ensure the velocity within the pipework is above 0.75 metres per second which is also known as self-cleansing velocity.

    Calpeda
    Varisco
    Self Priming Pump Image

    In this article we’ve covered some of the biggest issues that people have with self priming pumps, however for your specific pump model please refer to the O&M manual which can be found at www.BEPumps.co.uk. Find your pump, and click the  downloads tab.

    For more information on self priming pumps. BEPumps has a great article titled A Simple Guide To Self-Priming Pumps or visit BEPumps Youtube.

    It come with great pleasure to have the Varisco Pump J Range, Calpeda A Range and Various Ebara Self Priming Pumps as part of the BEPumps Family. Our engineers have a wealth of experience in working with these pumps, fault finding, system optimization, installing and Repairing. Look no further for Self Priming Pumps!