Mobile calibration setup for flow meters

How do you know for sure that the gas flow that you measure or set is the right one? The answer is quite simple: make sure that the flow instrument you are using to measure the gas flow gives the real value. Therefore, calibration (and adjusting) of the flow meter once a while is necessary.

What is calibration? 

Calibration is comparing the measurement value of a device under test - DUT - with a known (reference) quantity. Results of a calibration are stored in a calibration certificate.

In this particular case,  Bronkhorst has developed a mobile calibration setup for a customer in the chemical industry who uses a lot of mass flow meters and flow controllers. This customer was interested in in-house calibration equipment for his flow meters, because it would reduce the downtime of his installation and he would be more flexible in choosing the moment for this performance check. 

Process solution

At the gas inlet of this setup, a shut-off valve and a filter are used to prevent dust or other particles from passing. Next is a pressure meter to set and read out the correct pressure. Then we have a thermometer followed by the mass flow device under test -DUT-, which can be a mass flow meter or flow controller. Finally, the setup consists of two reference mass flow meters in parallel. In this case one for small gas flows up to 20 l_n/min of air (EL-FLOW Prestige or EL-FLOW Select series) and one for large gas flows up to 1200 l_n/min of air (EL-FLOW Select series), that have been calibrated to national standards.

This setup is a way to test whether the mass flow device is suitable and good enough in terms of accuracy and function. When the deviation between the test device (DUT) and the reference device is within the permissible tolerance, no further action is required. When the deviation is outside the permissible tolerance, it is recommended that you send the mass flow meter to Bronkhorst in order to have the deviation corrected.