Tip of the Week : How does a calibration work ?
What is calibration?
The biggest flaw of a measuring device is that it drifts more or less with time. To perform a calibration, compare a device under test (DUT) of an unknown value with a reference standard of a known value. The purpose of the procedure is to verify the accuracy of the unknown value of the DUT.
For a more formal definition of calibration, we turn to the world measurement system coordinator, the BIPM (Bureau International des Poids et Mesures). Based in France, this organization’s mission is to ensure the worldwide unification of measurements.
There are different calibration disciplines, each with varying types of calibrators and calibration references. The most common calibration disciplines include Electrical, Radiofrequency (RF), Temperature, Humidity, Pressure, Flow & Dimensional.
What is the purpose of calibration?
Calibration helps keep the industrial world running, functioning, and safe. Without calibration, all maintenance actions would become less effective over time. Regular calibration helps prevent failures, keeps production and testing machines safe, and maintains their high-performance levels over the years.
Also, calibration promotes or enhances scientific discovery, industrial manufacturing, and international trade.
How is a Calibration Performed?
There are several calibration methods; depending on which instrument you decide to calibrate and its chosen scheme. Here are the two most frequently used procedures:
1. Calibration by comparison with a source of known value.
Let’s take the example of the calibration of an ohmmeter. To do this, we will make the ohmmeter measure a standard reference resistor, which provides a known value in ohms, which allows us to see if the ohmmeter is in specification or not. Another reference device can also be used do the reference. Let’s retake the example of our ohmmeter. Instead of taking a calibrated standard reference resistor, we take a resistor of unknown value, on which we take the first measurement with our ohmmeter to be calibrated.
We take a second measurement with a reference ohmmeter (calibrated). We compare the difference in value between the two measurements to see how far our ohmmeter has drifted. Those procedures apply to any instrument.
2. Calibration by comparing the measurement of the DUT with the measurement of a universally defined value.
A variation of source-based calibration is to calibrate the DUT against a source of known natural value, such as a chemical melting or freezing temperature of a material like pure water.
From these two schemes, many variations are possible depending on the discipline and the instruments to be calibrated.
To perform a calibration, the device used is sometimes called a reference calibrator. A reference calibrator will allow the testing and calibration of a machine more efficiently and accurately. Indeed, the calibrator’s system integrates the reference standards, which allows a higher degree of accuracy—often equipped with connectors allowing the user to quickly and safely connect to the tested device. The calibrator also has a man-machine interface developed with a menu, options, and buttons, facilitating the use and increasing the accuracy of the measurement.
To increase operator efficiency and speed his performance, it is common to use calibration software with a calibrator. That kind of software allows the user to automate the calibration process while calculating their calibration uncertainty. On It will enable users to limit uncertainty or even procedural errors. It is an investment that is often very relevant because of the return on results it provides.
Who does it?
The calibration can be made in any location, depending on its diverse functions or a dedicated calibration laboratory can make them.
An authourised manufacturing engineer, an instrumentation technician, or a maintenance manager can perform these tasks within in a company.
Several functions have the capacity and accreditation in the laboratory, such as a metrologist, a laboratory manager, a calibration engineer, or a calibration technician.
What certifications are needed to perform them?
A calibration laboratory or a company that has received accreditation from a laboratory often provides a certificate with an instrument’s calibration. The calibration certificate provides essential information to give the instrument owner confidence that the device has been calibrated correctly and to help prove the calibration.
A calibration certificate may include a statement of traceability or a list of the calibration standards used for the calibration, all data resulting from the calibration, the date of calibration, and possibly pass/fail statements for each measurement result.
Calibration certificates vary by country, standard, technology, and industry of the products calibrated. Calibration certificates from an accredited calibration process are subject to precise requirements found in the international standard ISO/IEC 17025.
When calibrations are performed, it is crucial to have confidence in the process. Accreditation of calibrations provides this confidence. Accreditation gives the owner of the instrument confidence in the calibration procedure.
Calibration accreditation means that a calibration process has been examined and found to conform to internationally recognized technical and quality metrology requirements. ISO/IEC 17025 is the international metrological quality standard to which calibration laboratories are accredited.
How ATEQ proceed
At ATEQ Aviation, we perform our calibrations using reference calibrators, all managed by calibration software.
We recommend the calibration of our equipment every year. The ATEQ period of calibration is only a recommendation. It is forbidden to force a customer to do a calibration. If you wish to keep all your measuring devices’ efficient and precise, you need to follow the recommendation.
We have standards certified by our metrology department. During our calibration and comparison, we apply each of them. After that, we issue a calibration certificate to prove to your customers that your equipment is ideally within the standards.
Each of the subsidiaries does perform the calibration process following the calibration process imposed by the metrology center.
ATEQ is committed to producing the best aeronautical test equipment on the market and entrusts the sale of its products to a network of value-added resellers. We offer a complete range of products and 100% in-house customized hardware and software solutions, adapted to all requirements: pneumatic, electrical, and electronic safety systems testing.
ATEQ Aviation offers you a complete range of services dedicated to your performance to complete our product offer. With more than 40 years of customer support experience, ATEQ Aviation’s maintenance is guaranteed for six months. ATEQ Aviation has the tools, inventory, and expertise to quickly get your equipment back in service and save you valuable time. The entire ATEQ Aviation team is committed to providing fast and reliable responses. Contact us for calibration, monitoring, overhaul, troubleshooting, and real-time maintenance.