Calibration and Its Growing Importance

Calibration and Its Growing Importance In today's world where technology develops at a dizzying pace, the success of work conducted in scientific research, industry, commerce, defence and similar fields depends on precise and accurate measurements. Yet we generally never consider that all the devices we use could produce incorrect measurements. A device being in working order and appearing neat seems sufficient for the reliability of measurement results. When a device fails to function properly, we send it for servicing and repair, and we fall into the prejudice that everything is fine once it has been repaired. Unfortunately, even a repaired or newly purchased device's measurement result reliability must be guaranteed. This is precisely where calibration comes into play and, so to speak, saves the day. Yes, this may sound like a bold statement, but I believe the few examples I will give you will deepen your thinking on this matter. For instance; would you want to travel on an aircraft with a faulty altimeter? Or shop using a jeweller's scale that measures incorrectly, or use a blood pressure device that takes wrong measurements. To make it even more serious, what if the internal temperature of an incubator in a newborn unit is not suitable for the baby? The financial loss to a distribution company measuring electricity and gas to consumers 1 per cent lower than actual consumption? Let us think about how incorrect measurements in anaesthesia or medication dosages could risk human life. There are many more examples that could be cited. Of course, none of us want to expose ourselves to such risks. This is precisely when we must put into operation the process we call calibration. But what is this calibration?

What is Calibration?

To explain, calibration is a series of operations that determine the relationship between the values indicated by a measurement device and measurement system under specified conditions and the known values to which the measured quantity corresponds. It can also be explained as the comparison of test and measurement instruments with reference standards (etalons) whose metrological properties are known under specified environmental conditions (temperature, humidity, vibration, etc.), and the detection of the deviation of the value shown from the reference value. Calibration is not: • Adjustment, • Repair, • Maintenance. Therefore, since calibration is not an adjustment or error correction procedure, a device that has been calibrated does not mean a device with zero error. Calibration is important in almost every area of our working activities. All these devices and more that we encounter in many fields, particularly industry, and exemplified below require reliability as a matter of great importance. • Devices used for production processes, • Test and measurement instruments used for product characteristic inspection, • Test and measurement instruments used in incoming and acceptance testing, • Devices used in research activities, etc. To explain some important topics related to calibration in a few points:

1) When is Calibration Required?

• If the device has never been used or is newly purchased, • If the device has malfunctioned and suffered mechanical impact, • If the device has not been used in accordance with the user manual, • If functional failures have occurred in the device, • If the adjustment mechanism has been tampered with, • If there is doubt about the results obtained from the device.

2) How is Calibration Frequency Determined?

It is also not expected that a calibrated device will continue to produce measurements of constant accuracy. Therefore, the calibration periods of devices are determined according to their use. When determining this interval, the results obtained between two calibrations should not negatively affect the actual measurement result. The time interval between calibrations varies depending on the situation and depends mostly on factors such as storage conditions, calibration method, frequency of use, frequency of desired measurement, accuracy of desired measurement, wear effect and the stability of the instruments. Information about calibration intervals can be obtained from the device's seller, manufacturer or national standards. The device's: • Measurement uncertainty, • Stability, • Purpose and frequency of use, • Experience and standards, etc. are the main factors that guide us in determining calibration frequency.

3) What Should the Environmental Conditions be for Calibration?

• Environmental conditions should be stable. • Traceability of the calibrator used must be ensured. • The measurement range of the device must be determined. • Reference device characteristics should be good. • Calibration should be performed in accordance with measurement quality. • Calibrations must be performed by trained personnel. • Regardless of what the actual accuracy grades are, the international validity of the measurements carried out must be ensured and these measurements must be traceable to an international measurement standard with regard to their precision.

Work and Innovations in the Calibration Field in Our Country

In Turkey, work was first initiated by TÜBİTAK in 1981, and in 1988, a secondary-level laboratory was established by TSE to provide calibration services. Currently, there are many accredited laboratories conducting secondary-level calibration, led by the National Metrology Institute. Like in our country, every country has an organisation that develops and maintains numerous measurement standards. While working on such international standard-related matters, at the highest level, measurement standard comparisons between the national centre and the centres of other countries ensure the compatibility of measurements carried out nationwide with similar measurements within and outside the country. This accepted standardisation and certification is the factor that ensures reliability and international validity. The Turkish Accreditation Board (TÜRKAK), which contributes to ensuring international validity and, under the supervision of the Ministry of Foreign Affairs, carries out the task of accrediting conformity assessment bodies in our country and monitoring that these organisations continue their operations in accordance with international standards, and which currently undertakes very important work, plays a key role. Thanks to these organisations, accreditation awareness in our country is developing day by day. With all these sections, we can have general information about calibration. The statements we have explained should actually bring home to us as a country how sensitive we should be on this matter. If we proceed with this understanding, many changes that could be made in various fields will emerge. There are currently some steps we expect to be realised, particularly in engineering and science faculties. For example: • Calibration awareness to better understand how precise the analyses conducted in the laboratory need to be, • The increasing importance of metrology and quality control courses during student education, • Encouraging students in project and thesis work to develop instruments that will benefit industry's standardisation and quality control, • Visits should be organised to instrumentation and metrology laboratories, and during these visits, awareness should be developed about the economic losses that may result from quality control deficiencies. Such work will prioritise the increase of the population aware of standardisation and quality control concepts and will enable improvement in quality. Therefore, to meet demands, companies will initiate work in this direction to increase their efforts. While aiming to always move towards better things as a society, our need to always search for higher quality will also be met from the domestic market. It is to be hoped that by working with this awareness in all sectors, we can achieve the status of a country with the best production potential.   Süheyla Çalışkan Yılmaz Laboratory Manager İldam Laboratory Equipment Inc.