Shut Down Tip – Avoiding a Blocked Compound Pump

With everything that you’ll be thinking of ahead of a shut down one thing people often overlook is cleaning their compound dosing pump for their mass finishing machine. Whilst usually it’s a case of putting a compound drum at the bottom of the non-return valve and the pump just works when it has the chance to stand idle for a period of time it is wise to give it a little attention.  Many pumps contain diaphragms and these use a plastic tube which is opened and closed to encourage the compound to move.

Compound is surfactant based and as such has a tendency to crystallise when it is allowed to stand, becoming solid. Whilst this may not be obvious to the naked eye it is common to find our customers starting to use their machines again and reporting that the compound pump has broken.  This can easily be avoided by taking the following actions:


  1. Record your pump settings before doing anything – write them down

    This model pump has two dials with variable settings to 100%
    This model pump has two dials with variable settings to 100%
  2. Remove the compound drum from under the pump and replace it with a bucket full (10ltrs) of warm water
  3. Set the pump controls so it runs at maximum (in the case of the photograph here set both dials to 100%)
  4. Turn the machine on and allow the water to prime all through the pump and keep going, cleaning all compound pipes until water is seen arriving into the mass finishing machine bowl
  5. Turn the machine off – it is ready for the shutdown


Should you not do this before a lengthy period of none-use (this can vary depending on the compound used and its viscosity, chemical contents, etc…) and you find a blockage this can be cleared by following steps 1 to 4 above. Should the compound blockage be in the tube from the pump to the machine there is a good chance this will be sufficient to free it.  Should it be in the diaphragm then despite the pump ‘pulsing’ you will not see anything being drawn through the pump and to the machine. To tackle this:

  1. Loosen the fitting on the top of the pump which connects the tube from the pump to
    Rear of pump showing location of tubes, fittings and bleed screw
    Rear of pump showing location of tubes, fittings and bleed screw

    the machine (keeping it loosely covered.  If the blockage is minimal compound will soon ‘pulse’ into the air (depending on the strength of your pump)) (note – if your pump has a bleed screw there may be no need to remove the top fitting, only to open the bleed screw)

  2. Keep the machine working until compound is seen pulsing out of the top of the pump
  3. If no compound is seen grab the tube which connects the pump to the compound drum (or water bucket at this time) and wiggle it firmly. If there are air bubbles in the tube this will encourage them to move to the pump until they are pulsed out of the top
  4. Once the pump is running reconnect and tighten all fittings, ensure compound is being delivered through the tubes and into the mass finishing machine and then reset the pump to your former (pre-determined and recorded) settings


Should you need any help with the tips above or just a chat about your finishing equipment and its operation please complete our online form at


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Steve Lewis-Brammer NewPost written by
Stephen Lewis-Brammer
General Manager

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