Chemicals Dosing Pumps Calibration Basics

Calibration of chemical feed pumps is important to ensure that the proper amount of water treatment products are being fed to your systems.  All chemical feed pumps are designed to pump at a certain rate;  however, the actual flow rate can vary depending upon many conditions.  Factors such as discharge pressure, chemical viscosity, type of suction (flooded or lift), and pump age will effect the flow rate.  This simple procedure should be used on a regular basis to ensure that you are feeding the proper amount of product to your water systems.



 Prior to running calibration on chemical pumps, review product MSDS forms and use proper personal protective equipment.

    If you are using the same calibration cylinder to calibrate multiple pumps, be sure to rinse it with water between calibrations.


      Calibration Notes

      • If possible you should run the calibration with the pump connected to the system that it feeds.  The more closely you replicate the actual operating conditions of the pump, the more accurate your calibration will be.
      • Most calibration cylinders provide both mL and GPH.  If mL is the only scale provided, then be sure to record your starting level before running the test.
      • Run the calibration with the pump set to the actual speed and stroke setting that the pump usually runs at.  Use this formula to calculate the capacity at this setting:

       (Pump capacity, gph x Pump speed, % x Pump stroke, %)



      (1, gph x 50% x 50%) = (1 x 0.5 x 0.5) = 0.25 gph 


      Calibration Procedure


      1. Calculate the capacity of the pump at the speed and stroke rate at which the test will be run.
      2. Fill the calibration cylinder with the product that the pump is feeding.
      3. Record the starting level of the calibration cylinder.
      4. Run the pump for the desired amount of time, generally 0.5 - 1.0 minute.
      5. Record the ending level of the calibration cylinder.
      6. Calculate the actual feed rate (assuming a 1 minute test):

      ((mL pumped, 1 min x 60 minutes) / 3,785)) = gallons per hour



      (50 mL x 60 minutes) / 3,785 = 0.79 gallons per hour 


      Depending on your system, you will need to adjust your pump or controller settings to account for any difference between the design and actual feed rates.

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      Aldo Zaffalon
      Aldo Zaffalon


      Water treatment automation expert, with over 25 years of experience in industrial water treatment automation, marketing, sales and engineering.

      5 Responses

      Aldo Zaffalon
      Aldo Zaffalon

      June 15, 2017

      A well-calibrated pump allows for the correct amount of chemical to be fed. As Baden Bills mentioned, it prevents problems in the process but also, assures, that chemicals are not fed in excess. Excess chemicals dosed go to the drain aggravating the waste disposal and increasing the costs of operation.

      Braden Bills
      Braden Bills

      June 12, 2017

      It’s interesting that chemical dosing pumps can clean things out! I can understand why it would be so important to keep them calibrated. Otherwise you would run the risk of things going wrong!

      Wasit Ismi
      Wasit Ismi

      November 17, 2016

      Such an important thing to do with the people who are in the process of making the most difficult decisions to make sure the answer to the question of having higher cost of chemical


      March 15, 2016

      MechServ, the best installation for a diaphragm pump is with a flooded suction. We strongly recommend you to consider changing the installation. With the current configuration, the only option is, to use the cylinder in the discharge. Thank you


      March 15, 2016

      We have many of these pumps installed on top of the chemicals containers. How do we install the calibration cylinder in the suction?

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