Definition of calibration
The operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication.
The purpose of calibration is to determine the metrological condition of a calibrated instrument, which determines its suitability to perform measurements, including the transmission of a unit of measurement, or to certify that a calibrated instrument meets specified metrological requirements, whereby the calibration result is stated in the calibration certificate. During calibration, measurement coherence must be maintained, i.e. there must be an uninterrupted chain of references to a national or international standard.
Accreditation should be understood as formal recognition by an authorised accreditation body of competence of organisations operating in the field of conformity assessment, i.e. certification bodies, inspection bodies or laboratories to perform specific activities. Authorisation of the accreditation body is usually obtained from the government.
Accreditation serves to build and strengthen confidence in results of calibrations, tests and inspections, certified goods and services, qualifications of certified persons and certified management systems.
Principles of accreditation are included in international standards and guidelines, which define requirements both for accrediting bodies and for conformity assessment bodies subject to accreditation. Obtaining accreditation means that accredited entities have been assessed according to these standards and guidelines.
For accredited bodies
- certificates, test reports, calibration certificates and inspection reports issued by the PCA certification bodies, inspection bodies and laboratories may be recognised by the relevant institutions in countries which are signatories to Mutual Recognition Arrangements (MRA) or Multilateral Recognition Arrangements (MLA)
- accreditation is an objective proof that organisations operate in accordance with best practice
- accreditation is a significant argument when selecting suppliers on the national and international market.
- accreditation increases credibility of product certification results
- accreditation influences high quality of products and services and competence of personnel
- accreditation enables reliable and precise results of analyses and tests in areas related to safety, health and environment (e.g. medical analyses, mechanical tests, chemical tests)
- accredited entities provide reliable information on the basis of which decisions can be taken, e.g. in the field of environmental protection
- accreditation contributes to the elimination of barriers to trade through mutual recognition of conformity assessment procedures (free international trade is a stimulator of economic growth).
- accreditation is an essential tool in decision making and risk management. Organisations can save time and money by choosing an accredited and therefore competent conformity assessment service provider
- accreditation can serve as a means to access export markets in Europe and worldwide – following the principle “tested or certified once – accepted everywhere”
- accreditation ensures precise measurement and testing according to best practice, reduces the number of defective products, lowers inspection and production costs and enables the implementation of innovative solutions
- accreditation reduces risk in business relationships.
Metrology tasks in the management system and the way they are performed result from the system established in the organisation, its scope, requirements of reference documents, processes performed in the organisation, products manufactured or services provided, legal and other provisions, customer requirements and expectations, the organisation’s strategy and policy and many other external and internal factors including personnel competence.
When establishing a management system complying with the requirements of a standard (ISO 9001, ISO 1401, PN-EN 18001, ISO TS 16949, ISO 22000), it is necessary first of all to analyse the requirements of the standard relevant for the system and then to determine the metrological tasks on this basis.
Metrological tasks concerning the product/service in the quality management system result from the requirements of the current PN-EN ISO 9001:2009 standard and are specified in the its particular sections: 7.1, 7.2, 7.6.
The organisation shall determine the monitoring and measurement to be performed and the monitoring and measurement equipment needed to provide evidence of conformity of the product with the specified requirements. The organisation shall establish processes to ensure that monitoring and measurement can be, and are carried out in a manner that is consistent with the requirements for monitoring and measurement.
The calibration of a particular measuring instrument should be repeated for as long as the instrument is in use and serves for measurement.
The timing of recalibration should be determined by the user of the measuring instrument himself and should be recorded in the quality manual or in related documents, e.g. general procedures (if he applies a certified quality management system e.g. according to ISO 9001) or based on experience.
For simplified purposes, it is assumed that an instrument should be recalibrated at least once a year. Instruments that are portable, shock-prone and are equipped with mechanical or electrical regulators, as well as those intensively used, should be calibrated more frequently.
- the risk that a measuring instrument may exceed the error limit during its use;
- cost of necessary corrective actions when an instrument was found not to be suitable for long term use;
- tendency to wear and drift;
- the extent and intensity of use;
- variability of characteristics due to the influence of various factors (environmental conditions) such as ambient temperature, humidity, pressure,
- maintenance and service records;
- frequency and quality of periodic checks between calibrations;
- degree of training of operating personnel.
Metrological supervision over the possessed measuring equipment is indispensable, although its type, scope of supervision and periods of its exercise should be selected according to needs, if they do not result from legal regulations. Properly maintained measurement equipment will be our guarantee of reliable measurements resulting in appropriate quality of products, services and tests. The costs of negligence may considerably exceed the expenses related to supervision, often exposing the business entity to a loss of credibility, which may entail the loss of a customer.
The Laboratory is equipped with
- calibration thermostats; range (-30 ÷ 240) °C,
- horizontal tubular furnaces; temperature range (200 ÷ 1200) °C
- temperature calibrators; range (50 ÷ 1100) °C
- water triple-point cell 0°C
- pressure press; range (0 ÷ 700) bar
- multi-channel scanners
Measuring standards consistent with the national standards of measurement units
- platinum sensors of the SPRT Pt25 resistance thermometer
- platinum sensors of the Pt100 resistance thermometer
- platinum thermocouple -10% rhodium / platinum (type S)
- platinum thermocouple -30% rhodium / platinum -6% (type B)
- calibration resistors
- digital meters
- multifunction calibrators