Frequently Asked Questions


  • Q: Is it important to have a fresh battery?
    • A: The flow rate will decrease with use, so having a fresh battery is important for consistency.
  • Q:  Is it important to have both pumps running at the same flow rate?
    • A:  That can depend on the type of experiment you wish to run.  Running different flow rates will yield different results.
  • Q:  Will air bubbles inside the unit throw off consistency?
    • A:  Small air bubbles are acceptable, but large ones need to be removed.

Safety/Equipment Lifetime

  • Q:  Is it harmful to the pumps to run them without water going through them?  Is there a danger of overheating the pumps?
    • A:  Yes.  Pumps should not be run dry.
  • Q:  What is the max temperature that the pumps are safe to submerge in?
    • A:  Each Pump should have a listed temperature that they should operate within. If the pump does not list it’s rated temperature, assume 60°C as the max safe temperature.
  • Q:  Is it possible to use this equipment with other liquids?
    • A:  Yes, but it is recommended that only water should be used.  Different chemicals could cause premature corrosion in the metal pipes, or could cause the plastic parts of the pumps/units to deteriorate.
  • Q:  What range of flow rates can these units achieve?
    • A:  ~2 – 25 ml/s


  • Q:  If I use colored dyes for demonstration purposes (or similar staining substances), what is the best way to clean the units afterwards?
    • A:  Follow these steps:
        1. Rinse as much excess dye out from the unit.  The easiest way to do this is to use one of the pumps to run clean, warm water through it and running the exit tube straight into the sink.  Use water at the highest safe pump temperature for the best results.
        2. Repeat step 1, but add soap to the water.
        3. For remaining stains, take a glassware cleaning brush and warm soapy water to further clean them.
  • Q:  How should the units be stored?
    • A:  Clean and drain each unit as well as possible, then store them on top of the tray used for the experiment.  The water that was left from draining will fall into the tray and evaporate, protecting anything else stored in the same cabinet.

Interested in purchasing DLMs for use in your classroom or lab? Please fill out the form on the contact page!

Additional questions?

Email: dlmfrequentquestions@gmail.com