Marcel Katerberg
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For us, as supplier of flow meters and flow controllers for low flow rates of gases and liquids, the most essential thing is supplying a proper working measuring device of high quality to our customers. Therefore, quality control is important. As a final step in production, we calibrate all our flow meters to provide accurate flow measurements.

As manager of the Bronkhorst Calibration Center I sometimes experience misinterpretation concerning calibration and its meaning. Occasionally calibration gets confused with concepts like re-calibration and adjustment. Therefore, in this blog I want to clarify these concepts.

What is the difference between calibration and recalibration of flow meters?

In short, calibration is nothing more than comparing the output of a measuring device with a reference. For Bronkhorst devices this can be done by a Bronkhorst service office, Calibration Centre or by the end user if they have the right equipment. Re-calibration is a popular word for doing a ‘re-‘check and is often referred to as when a purchased flow meter has been sent back to the factory for a periodic calibration check. So, re-calibration is actually the same as calibration, the flow instrument will be compared to a fixed reference, again. In principle calibration does not involve any adjustment.

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What is adjustment and when is this necessary?

In practice, the most essential thing for the customer is to have a proper working measuring device, and therefore, subjecting a meter to a periodic calibration check is also called a calibration “as found”. If the meter shows a deviation outside its specification limit, adjustment is advised. Adjustment can be carried out by a Bronkhorst service office, a (Bronkhorst) calibration center or by the customer if he has the right equipment. The instrument will be adjusted to indicate the true value again. After the adjustment the instrument will be subjected to a calibration “as left” and that comes with the calibration certificate.

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Why is calibration necessary?

Every instrument is subject to aging, wear and dirt. In order to ensure the instruments measure values representing the truth, a periodic check is often recommended. For some applications a periodic check is even required due to legislation, norms or directives.
Minor deviations can be caused by aging of mechanical and analog electric components, this is almost unavoidable. If the deviation is more than a few percent, this is usually caused by dirt or wear. In this case full service, repair and new adjustments are recommended for the instrument.

Check out the top 4 questions about calibration on our FAQ page:

  1. How often should I perform a calibration check on my mass flow devices?

  2. How to interpret the data and terminology on Bronkhorst calibration certificates?

  3. In case of an emergency, can I clean, repair and calibrate the instruments myself?

  4. Is it possible to use the flow meter/flow controller for gases other than they are calibrated for?

Bronkhorst Global Service Offices & Calibration Centre

At Bronkhorst Global Service Offices and at our Calibration Centre in Ruurlo (NL) we are capable of calibrating and adjusting Bronkhorst flow devices and also third party instruments within our scope. Learn more about our Calibration Centre.

Besides that, Bronkhorst Calibration Centre has been accredited as ISO 17025 compliant by the Dutch Accreditation Council (RvA), providing international recognition of its technical competency and qualification. Read our blog about the Bronkhorst Calibration Centre.

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