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PLP Sanitary Lobe Pump Troubleshooting

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    What are the main malfunctions and problems with the PLP Sanitary Lobe Pump?

    Malfunction in Sanitary Lobe Pumps may be caused by various reasons and is not necessarily the pump itself. Issues with the pipework or other fluid accessories within the system can be contributing factors. Furthermore, if the operating conditions differ too greatly from the provided specification for which the pump was selected for can also be a major contributing factor.


    Consequently, it is always recommended to check the following first:

    • Has the pump been installed correctly?
    • Are the operating conditions still according to the initial specification?
    • Are the other fluid accessories within the pipework functioning correctly?

    In general, the following malfunctions can be identified:

      1. Pump provides no flow
      2. Pump provides irregular flow
      3. Capacity is too low
      4. Pump overheats
      5. Motor overheats
    1. Excessive Screw / Rotor wear
    2. Excessive wear of shaft sealing
    3. Pump vibrates excessively or makes too much noise
    4. Pump has seized
    5. Pump stops upon startup

    Overleaf is a table of the possible causes and solutions of these malfunctions.

    Wrong Direction or RotationHave a qualified electrician reverse the direction of rotation of the electric motor
    Pump is not completely filled with liquidFill the pump casing entirely with fluid and fit a non-return valve to the suction side
    Insufficient Suction Pressure / NPSHaIncrease the suction pressure, lower position of the pump further below the fluid level, enlarge suction pipe ø, shorten/simplify suction pipework, reduce operating speed, reduce product temperature
    Excessive vapour is present in the suction line
    Air is entering the suction lineCheck Connections
    Gas in the suction lineVent suction pipe/pump casing
    Insufficient static headIncrease the liquid level
    Product viscosity is too highLower the operating speed/increase product temperature
    Product viscosity is too lowIncrease the operating speed / lower the product temperature
    The product temperature is too highCool the product/pump casing
    The product temperature is too lowHeat the product/pump casing
    Foreign particles are in the productClean the system / install a suction filter sized according to the passage of the max solid of the pump
    The pressure on the delivery side is too highCheck to pipe for obstructions / simplify the discharge pipework
    Pump casing distorted by pipingCheck alignment/support the piping & install flexible couplings
    Speed too highLower the speed
    Speed too lowIncrease the speed
    Insufficient flushingIncrease flushing capacity/pressure
    Worn out bearings/gearsReplace the worn-out parts
    Safety Valve is openCheck if the delivery valve is open / check the piping for obstructions / check the piping for pressure loss



    Inspection & Maintenance Schedule

    Routine inspection and maintenance can avoid unnecessary and expensive downtime as well as operating costs. It is recommended to regularly check:

    • If the pump functions properly – excessive noise levels may indicate wear problems to bearings and gears, dragging of rotors/lobes on the pump casing or cavitation.
    • Pressure and Flow of the flushing system, if present
    • The temperature of the heating/cooling system, if present
    • Oil level in the gearbox – If the oil level has reduced, check the pump for oil leakages
    • Monitor regularly the pump suction and discharge pressure conditions to ensure they are in line with typical system levels.

    Oil Changes

    • 300 operating hours after the initial commissioning
    • Every 3000 operating hours or at least every 3 months
    • If not being used regularly, every 2000 operating hours, or at least every 3 months

    For more help and guidance on maintaining your Lobe Pump contact Tapflo UK today by using our live chat system or by email: [email protected]

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