Many customers of calibration services are unaware of the options available to them for the types of calibrations that can be performed. When equipment is sent to the calibration laboratory, little information is provided by the customer concerning the services required for the equipment. Usually, customers just want it ‘calibrated’.
Having the proper knowledge of the types of calibrations that are available is important for all organizations to ensure that they are getting the proper calibrations performed and that the calibration certificates they receive contain the information that is required.
There are two types of calibrations that can be provided, nonaccredited and accredited.
A nonaccredited calibration is also known as a commercial calibration, standard calibration or NIST Traceable calibration. This calibration is the basic calibration most are familiar with. The calibration will be performed with specific calibration procedures under the guidelines of the calibration laboratory’s quality system. The calibration certificate that is issued will contain the basic equipment description information for the item being calibrated, such as manufacturer, model number and serial number, the dates of the calibration, next calibration due dates, environmental conditions during the calibration, and likely a pass/fail or intolerance/out of tolerance designation.
The certificate will also include the equipment used by the calibration provider to perform the calibration for standard traceability and the appropriate technical or quality signatures for authorization.
In addition to all of the information provided on the certificate for nonaccredited calibrations, accredited calibrations must meet additional, specific requirements that conform to the ISO/IEC 17025 international standard. These include:
Accredited calibrations contain all ‘as-found’ and ‘as-left’ measurement data for their calibrations. Having the calibration data can provide customers with a history of measurement trends for each item of equipment.
Measurement uncertainty is a combined measurement of the error sources and repeatability of the equipment during a specific measurement. This value gives customers additional information when analyzing the measurement results and measurement accuracies.
The accreditation logo will show the accreditation body that the laboratory was accredited by and will contain the laboratory’s accreditation number. This logo proves that the calibration provider has met the ISO/IEC 17025 guidelines and has the competence to properly perform the required measurements.
During the accredited calibration, technicians must use properly validated calibration procedures and must use the standards listed on their ‘Scope of Accreditation’, which are usually the most accurate standards within the laboratory.
An accredited calibration to the requirements of ISO/IEC 17025 is recognized internationally and is considered the highest level of calibration service that a calibration laboratory can provide.
Accredited Calibration Laboratories
All calibration laboratories can perform nonaccredited calibrations however, accredited calibrations can only be performed by calibration laboratories that have been accredited to the ISO/IEC 17025 standard by a recognized accreditation body. The accreditation body regularly audits the laboratory and its quality processes to ensure that the laboratory is following the management system requirements for the operation of the calibration laboratory.
The technical competence of the laboratory to perform the specific calibrations is determined by observing the measurement capabilities within the laboratory, verifying the reported measurement uncertainty values and comparing their measurement results with other accredited laboratories through proficiency testing.
Accredited laboratories provide the evidence that they have the structure, competence, resources and integrity to consistently obtain accurate measurement results.
It is ultimately the responsibility of the customer to understand and make the proper determination of the type of calibration that is required for their organization. So how do you decide which type of calibration service you need?
The first thing that should be considered is whether there are any regulatory requirements that determine the level of calibration required. Some industries have regulations that require accredited calibrations for their equipment. An organization’s customers may also dictate the types of services that are required.
Otherwise, the decision for the appropriate service should be based on how the equipment is being used. If the equipment is used in a low-risk environment where there are large specifications or just require a pass/fail criterion, then a nonaccredited calibration is likely sufficient.
Equipment that is used for critical applications or used within an organization to test or calibrate other equipment should have an accredited calibration performed. For example, if a set of gage blocks is used to calibrate your micrometers or calipers in-house or if a torque calibrator is used to verify torque wrenches before each shift, the calibrations for those items should be accredited.
If an accredited calibration is required, it is important to verify that the equipment is included within the calibration laboratory’s ‘Scope of Accreditation’. The Scope of Accreditation is a document that is issued for every accredited laboratory that shows the technical parameters, measurement ranges and best measurement uncertainty values for which it is accredited.
Calibration laboratories can rarely perform accredited calibrations across all calibration disciplines. Therefore, even if a laboratory is accredited, it may not be able to perform the accredited calibrations for the equipment or measurement parameters that you require.
is an ISO/IEC 17025 accredited calibration laboratory and can provide nonaccredited and accredited calibrations across a wide range of test and measurement equipment. For more information on how e2b calibration can assist you with your calibration requirements, contact e2b calibration.