When a measuring instrument is sent for calibration, after the process is completed it is returned to the user along with a Calibration Certificate. But what exactly is an accredited calibration certificate? What information is endorsed in it? What is the purpose of the certificate? How is this information useful?

 In order to understand what exactly a Calibration Certificate is, we must first familiarize ourselves with the meaning of the term ‘calibration’. 

WHAT IS CALIBRATION?

The word ‘Calibration’ may be used in several contexts. Formally, calibration is
the documented comparison of the measurement device to be calibrated against a traceable reference device. The reference standard may also be referred to as the
“calibrator”. Logically the reference is more accurate than the device to needs
to be calibrated.

But there is need that the reference device should be also calibrated. Calibration
can also be defined as the process that establishes, under specific conditions,
the relationship between the values of quantities indicated by a measurement
instrument and the corresponding certified values of standards – accompanied by
an associated statement of uncertainty.

 CALIBRATION CERTIFICATE:

 A calibration certificate is a record of the results of calibration performed on a specific Instrument or measuring equipment. This is also called as a calibration report.

Calibration certificate documents contain critical information about an equipment and details with regard to its calibration. While certain amount of flexibility is permitted depending on service level options and customer requirements.

The calibration certificate is the official document of record for the calibration of an instrument and provides traceability to the National Institute of Standards and Technology.

The accuracy and completeness of the calibration certificate in itself reflects the validity and credibility of the calibrating organization.

ISO/IEC 17025 ACCREDITED CALIBRATION & TRACEABLE CALIBRATION:

ISO/IEC Accredited Calibration

The difference between traceable and accredited calibration is a common question posed by customers while trying to determine what suits their product best. Knowing the significance of each can help them to fathom that the calibration needs of their instruments are met.

 An accredited calibration certificate is issued by an accredited laboratory. These are accredited by various bodies such as NABL, DKD, and others as per ISO17025. In such laboratories calibration is done as per relevant standards and procedures, which is accepted and approved during audits.

These procedures or standards are the basis of comparison for laboratory capabilities.

The Accredited Calibration certificate thus has more credibility as the calibration is performed as per certain standards, verified by accredited bodies and provides the user much more information like uncertainty budget, classifications as per standards, along with the measurement values at various points in the range.

 Accredited calibrations provide a certificate of calibration with the accrediting organization’s logo on the document. The calibration date is mentioned on the certificate and the calibration due date is only provided on the document when the same is specified by the customer or contractually agreed. A traceability statement is provided. Measurement data and uncertainty for each parameter tested during the calibration is provided.

 Every calibration certificate should contain some key elements.

1.       A title (ex. Certificate of Calibration and Traceability).

2.       Name and address of the laboratory wherein the calibrations were performed.

3.       Name and address of the customer.

4.       Unique identification of the calibration certificate.

5.       Identification of the calibration procedure utilized.

6.       List of standards used to perform the calibration including their calibration dates and traceability.

7.       Unambiguous identification of the instrument calibrated.

8.       Environmental conditions under which the calibrations were made that would influence the measurement results.

9.       Name, function, and identification of individual authorizing the calibration certificate (technician).

10.    Calibration results with the unit of measurement.

Factory Traceable Calibration:

Whereas manufacturer’s traceable calibration could be conducted with similar standards and the master equipment used could be calibrated. However they are not explicitly approved by accredited authorities. Also, the data provided in a manufacturing certificate, may not be sufficient to understand the equipment’s behaviour across the entire range. Generally, the manufacturer’s traceability certificate gives you an idea at no load and full load of the capacity, but not the entire behaviour across the range and its uncertainty.

 This service provides a calibration certificate with a calibration date and calibration due date. A traceability statement is provided. Measurement parameters not meeting the test specifications (out of tolerance) are identified and reported on the certificate.

 Both Accredited Calibration & Traceable calibration include a Calibration Certificate that accompanies the instrument when it is returned to its owner. The calibration certificate documents essential information about the instrument’s condition, and also provides details about out-of-tolerance conditions, special measurement conditions, and more. Each certificate includes a serial number that associates one calibration with one instrument.

 It’s important to note that non-accredited calibration laboratories are not required to have any type of formal quality system nor provide measurement data to their customers. They may not follow regulations that govern the technical aspects of the calibration laboratory to ensure that the proper training and methods are applied to the calibration process.

 Meanwhile, accredited calibration laboratories are governed by the international standard ISO/IEC 17025 and are regularly audited by various recognized accreditation bodies to test the laboratory’s technical competence and that they follow a proven quality management system. They are guided by quality and integrity in all aspects of their job performance.