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Air Operated Diaphragm Pump Troubleshooting

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    Diaphragm Pump parts dissasembledTo ensure safe operation and the life of your pump and to form part of a preventative maintenance schedule, routine and complete inspection of the pump is recommended. Routine Inspection can be done by frequent observation of the pump operation is required to detect problems.

    If the sound of your pump operating changes, this could indicate worn parts, leakages or a change in performance. The intervals for a complete inspection depend upon the operating conditions of the pump. The characteristics of the liquid, temperature, materials used in the pump and running time decide how often a complete inspection is necessary. Nevertheless, Tapflo recommends that customers should inspect their pump at least once a year.

    As part of this inspection, Air and Liquid Kits should be changed and Valve Kits should be changed once every 2 years. Tapflo recommends stocking at least a Liquid and Air Kit to ensure that expensive downtime is avoided.

    Diaphragm pump troubleshooting : Common problems

    Your pump won’t run

    Air pressure too low: The air supply pressure needs to be higher than 1.2 bar and greater than the system pressure that the pump is working against. Adjust the air supply pressure with the Air Filter Regulator. Ensure that the mains air supply pressure is adequate for your requirements.

    Blocked air connection or contaminated air valve: Check your air supply, is it clean, free of any obstructions or kinks? Additionally, check your air valve hasn’t been contaminated inside the pump.

    Blocked muffler or exhaust: This means the pump cannot expel air efficiently which has a direct effect on a Diaphragm Pumps ability to operate. Check whether there are any obstructions at the pump’s exhaust and check that the pump’s muffler is in good condition.

    Solids in the pump chamber: Solids that have settled in the pump chamber or body can block the diaphragms from moving, preventing your pump from operating. Solid particulates can also settle around the ball valve seats which can prevent the ball valves from re-seating properly which can lead to poor performance or even prevent your pump from working. Clean your pump and install a suitably sized filter on the suction of your pump to prevent the pump from becoming blocked inside.

    Damage diaphragms or ball valves: Damaged, broken or misshapen diaphragms and ball valves will reduce the efficiency of your Diaphragm Pump. This can be solved with regular checks to the condition of your diaphragms and ball valves, it’s important to carry out these checks regularly to increase your pump’s operating life.

    Blocked suction or discharge pipework: This will prevent your pump from functioning properly and could cause it to stall. Check the position of manual valves on the suction and discharge of the pump regularly, do this before turning the pump on to ensure that it isn’t put under stress. Cleaning of pipework if operating on particularly stick or solids laden fluids is also recommended as these types of process media can quickly reduce the internal bore of your pipework and change the system pressure requirements to the detriment of the pump performance.

    The liquid is leaking from your pump

    This certainly isn’t right, here are a few things that could be causing this and ways to check and rectify it:

    Loose side housings: The pump is sandwiched between approximately 6 tie rods, if these aren’t tightened to the recommended torque setting, liquid could leak from the side housing.

    Damaged O-Rings: If the O-Rings on your pump’s inlet or outlet manifolds have perished or are damaged, this could suggest that the mounting hasn’t been reassembled correctly after maintenance, it could also be caused by forcing the manifold positioning without loosening the side housings first which can deform the O-Rings.

    Diaphragm rupture: Causes of a failed or ruptured diaphragm include overuse, abrasion, chemical attack or overpressure to name a few. A rupture means fluid will leak into the air valve and leak through the pump’s muffler. Diaphragms will need to be replaced and should be checked regularly for wear during maintenance checks to prevent this from happening.

    Pipework problems: If your pump has not been matched for rigid pipework, for example, inadequate pulsation dampener or over the permitted loads for manifolds, pumps can become loose and cause leaks. Ensure the pump has been matched to your installation and adjust accordingly to eliminate stresses to pipework and the pump. This can be achieved by flexible expansion bellows a hose on the suction and discharge of the pump and/or installing a Pulsation Dampener.

    Poor flow or pressure

    Worn or blocked valve balls/seats: This will lead to fluid circulating inside of the pump and syphoning back through it causing a drop in both flow and pressure.

    Damaged diaphragms: Damaged or bent diaphragms can have a direct impact on the flow and pressure generated by the pump.

    Air leak or changes to the supply: As compressed air is the driving force of the AODD, any changes in the quality, flow & pressure of the air supply can have a direct impact on the performance of the pump. Therefore, routine checks are required to ensure that there are no air leaks, changes in pressure or flow to ensure good operating performance & reliability. It is also recommended to check the status of the air filter and moisture separators on the air supply line to ensure the air quality to the pump is adequate.

    Suction or discharge pressure changes: If the pipework becomes encrusted or has a leak it will impact the performance of your Diaphragm Pump. Routine checks on the integrity of connections for possible leaks or air ingress & cleanliness/condition of the lines are recommended, as well as valve positioning and suction & discharge pressure gauges to ensure that the system pressure remains within the working parameters of the pump.

    Blocked or worn air valve or muffler: Damage, corrosion or dirt on the air valve will affect the function of your Diaphragm Pump. Additionally, if the muffler is blocked, the pump cannot expel air effectively meaning the pump won’t operate efficiently. Monitor the performance of your pump, apply preventative maintenance measures and monitor the condition of the pump’s muffler to ensure the pump is performing reliably.

    Diaphragm pump troubleshooting & Solutions finder

    ProblemPossible FaultPossible Solution
    The pump does not runThe air pressure is to lowIncrease air pressure via a filter-regulator
    The air connection is blockedCheck/clean air supply connection
    Muffler is blockedCheck/clean/replace the muffler
    The air valve is defectiveClean/replace complete air valve
    Dirt in the pump chamberRemove debris from the chambers
    Diaphragm breakdownReplace diaphragm
    The suction is badThe suction connection is not tightTighten the suction line
    The suction connection is blockedClean suction line
    Muffler is blockedCheck/clean/replace the muffler
    Valve balls are blocked or damagedCheck the dimensions and shape of valve balls
    Valve seats are worn. The pump starts with high-pressure air in suction/discharge line dry suction against a discharge pressureCheck the dimensions and shape of valve seats. Start the pump slowly (see chapter 2.2 of manual) Vent suction/discharge line, wet the pump/start without discharge pressure
    The Pump runs irregularlyValve balls are blockedCheck the dimensions and shape of valve balls
    Sealing in centre block, air valve is defectiveReplace sealing. Clean/repair air valve
    Diaphragm breakdown valve seats are worn icing on the mufflerReplace diaphragm. Check dimensions and shape of valve seats. Improve air quality (see chapters 1.7.1 and 2.2.2 of manual)
    Bad flow/pressure





    Pressure fall in air supply. Pressure losses on suction side air supply/air valve leakingIncrease air pressure via a filter-regulator. Check/change installation on suction side. Check/repair/replace air supply/air valve.
    Suction or air connection blockedCheck/clean air supply/suction connection
    Muffler is blockedCheck/clean/replace muffler
    Valve ball worn or broken. Valve seats are wornCheck dimensions and shape of valve balls. Check dimensions and shape of valve seats.
    Air in liquidSeal suction line; check/refill container
    Diaphragm Breakdown. Icing on the mufflerCheck/replace diaphragms. Improve air quality (see chapters 1.7.1 and 2.2.2 of manual)
    Liquid leaks from the pumpScrews on the housing not properly tightened O-ring on manifolds damaged. Damaged diaphragm tension/stress form the installationCheck tightening torques of the screws. Replace O-rings. Check/replace diaphragms. Adjust installation, eliminate stress, when using a dampener provide separate support for it (see dampener IOM manual)
    Liquid comes out of the mufflerDiaphragm breakdownReplace diaphragm
    Diaphragm breakdownWrong selection of material. Too high pressure in the installation. Long periods of dry running. Too high pressure on suction side.Contact us for information on material selection. Use air treatment system for protection. When dry, run pump slowly (see chapter 2.2 of manual). Make sure there is pressure balance between the air and liquid side of the diaphragm.
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