What is calibration? Why calibrate? What are traceability, accreditation and calibration certificates? How often should one calibrate? Below you will find answers to this.
What is calibration?
Calibration is a comparison of an instrument to a normal one. Simply put, you check that the instrument measures the correct values. From the result of calibration one can examine the accuracy, and the difference between measured values and final values must be less than a certain tolerance. The calibration is performed under given conditions, preferably the conditions of use.
The normal should have an accuracy that is 3-5 times better than the calibration object.
Calibration is used to document an instrument's accuracy and quality. With a calibrated instrument you can be sure that your results are correct. There are also requirements for calibration intervals, based on industry and area.
By traceability is meant that something can be traced back to the origin. Traceable calibration means that the accuracy of an instrument can be traced back to the definition of the measurement size via an unbroken chain of calibrations where everyone has a specified uncertainty. Traceability is usually set to national or international standard. A typical range is "international standard - national standard - IKM standard - your instrument".
Being accredited simply means that you are an approved player of the service you perform. More precisely, it can be said that accreditation is an official recognition of an organization's competence and ability to perform specified tasks in accordance with given requirements. In Norway, accreditation is carried out by Norwegian Accreditation. IKM Laboratorium AS is accredited according to "NS-EN ISO / IEC17025" to perform calibration given in the accreditation scope "CAL009". A non-accredited calibration has no official recognition.
The calibration certificate documents the result of the calibration. It tells about the condition of the calibration object as it appeared during the calibration. The certificate must contain all the data on which the calibration result is based. Requirements for such certificates are set out in the standard "NS-EN ISO / IEC17025". Click here for more information about decision rule and statement of conformity.
How often should one calibrate?
Where necessary to ensure valid results, measuring equipment shall be calibrated or verified at specified intervals or before use. The calibration must have traceability to national or international standards. The standard "ISO 9001" describes requirements for calibration intervals. In order to be able to set these intervals, the manufacturer's recommendations are most often used.
Important factors in determining the calibration interval:
- Accuracy of previous calibration.
- Requirements for the uncertainty of the instrument or of the measurement you are going to make.
- The risk of exceeding the required accuracy.
- Potential costs if the measurement turns out not to have good enough accuracy.
- Type of instrument.
- Manufacturer's recommendation.
- Competence of personnel.
- Consequences of incorrect measurement.
- Environmental conditions (climatic conditions, vibrations, ionizing radiation, etc.)
- Guidelines for the determination of calibration intervals of measuring instruments
When do you need calibration?
- Fiscal measurement.
- Adjustable equipment.
- Areas regulated by law or regulation.
- Accredited companies.
- Certified companies.
- By conformity assessment.
- Final inspection according to a specification.