Calibration: Testing the tester instruments

Calibration plays a very significant role in any instrumentation. If you are using equipment frequently, like 50 times or more in a year, then it’s important to have them calibrated once in a year.

Risks of non-calibrating the testing and measurement equipment

Missing to calibrate your instruments may increase the error. According to Parag Yelegaonkar, Business Development Manager, Government Business, Testo India Pvt. Ltd., “If you are using an instrument for multiple products for measurements, it may provide you inaccurate or wrong decision; this can be catastrophic in some situations. Hence it is very important to calibrate the testing and measuring instruments once or twice in a year depending upon the frequency of usage of the instruments.”

We should not consider calibration as an action that merely fine-tunes test instruments. Calibration also ensures that equipment can be used safely and reliably. We will always get precise and accurate results if we use calibrated test equipment. Thus calibration may be considered as a form of quality assurance.

Vikram Bhansali, Director, Metravi Instruments Pvt. Ltd. points out some of the risks of not calibrating instruments as and when required and regularly; but not just limited to these:

• Compliance and safety issues: It becomes risky for your employees to operate uncalibrated work equipment and also leads to safety compliance hazards.
• Wastage of resources and raw materials: Having poorly calibrated equipment can lead to wastage of your resources, time and manpower as well as spare parts.
• Low quality of the final products: If you are unable to take accurate measurements, then it is bound to affect the manufacturing or production processes whereby you will face problems in term of the quality of finished products.
• Increased downtimes: Using uncalibrated equipment leads to increased downtime and unexpected failures as it can affect and damage other parts of your machinery and lead to wastage which can be pretty expensive for your business as well as risky for your employees to operate the uncalibrated equipment.
• Litigation issues: Badly calibrated equipment can affect the quality of your products and dent your reputation, attract litigation from customers and affect your business profits.

Instruments to be calibrated: How often?

All of us are aware that we must calibrate our instruments regularly. There is no ‘one-size-fits-all’ rule for an answer to this. Bhansali says, “Every instrument will have and has different calibration frequency requirement. The frequency with which calibrations should be carried out is an important, if sometimes difficult, question.” The same depends on two main concerns. Firstly, all measuring devices – whether they are simple, ‘fundamental’, or ‘sophisticated’ – change characteristics with time; the issue is how much do they change?

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• The accuracy of an instrument’s measurements starts to drop over time. You have to make sure the instruments don’t get ‘out of calibration’.
• New instruments should be calibrated relatively frequently in order to establish their repeatability
• Follow calibration intervals recommended by the manufacturers
• Calibrate your instruments before you start any major critical measuring project to ensure absolutely accurate results
• Calibrating after any major critical measuring project is also important to confirm the accuracy of your testing results for that project
• Accuracy of instruments depends on the environment, including temperature and humidity. If the two are on the higher side, calibration should be done frequently within smaller intervals.
• If the instrument’s reproducibility is shown, by successive calibrations, to be substantially better than the uncertainty required, then the interval between calibrations can be extended – perhaps even up to five years or so (if requirements in standards don’t specify otherwise), but at the other extreme – where the instrument’s reproducibility approaches the uncertainty needed – the calibration intervals should be much shorter, perhaps on a weekly or even daily basis.
• If your instruments took a hit, like a sharp physical impact on drop or if something knocked out the internal overload, you must send them out for calibration. Also, check the safety integrity checked.
• Some instruments may require certified and calibrated test equipment, regardless of the project size, and some may not. These requirements may not be explicitly stated, which is why you must review the specs before any test.
• Depending on the usage, you should calibrate equipment on a monthly, quarterly or semi-annual basis
• If you carry out a mix of critical and non-critical measurements, annual calibration would be a good option.

Missing to calibrate your instruments may increase the error.
Parag Yelegaonkar, Business Development Manager, Government Business, Testo India Pvt. Ltd.

Badly calibrated equipment can affect the quality of your products and dent your reputation, attract litigation from customers and affect your business profits
Vikram Bhansali, Director, Metravi Instruments Pvt. Ltd