- THE MAGAZINE
- WEB EXCLUSIVES
As an accredited calibration laboratory, the Oak Ridge Metrology Center (ORMC), a Department of Energy facility operated by BWXT Y-12 LLC, has certain expectations relative to calibration reports. In simple terms, the expectation is that the contents and traceability requirements of ANSI/NCSL Z540-1-1994 or ISO/IEC 17025: 1999 be incorporated.
What does this really mean? The requirements of the cited standards are, for the most part, clear and unambiguous. Based on recent discussions, the possible exceptions include how to demonstrate the chain of traceability and what data must be recorded.
Calibration laboratories are required to establish traceability of their measuring and test equipment by means of an unbroken chain of calibrations or comparisons linking them to the relevant primary standards. ORMC-issued calibration reports include the unique identification of the primary or secondary measurement standards (masters) used to perform a calibration and the expiration date for each standard. ORMC has on file the calibration reports for all of its measurement standards as provided by NIST or other calibration organizations that it may use.
When ORMC performs a calibration for a customer, that customer is provided with a single calibration report unless requested otherwise. Reports or certificates for the standards (masters) used to perform that calibration are not normally provided. Consequently, when ORMC purchases a calibration service, it expects a calibration report that contains the contracted information and identification of the standard(s) used. This is all that is necessary because ORMC contracts only with accredited laboratories or other laboratories whose competence has been examined and attested to by either ORMC or sister laboratories within the Department of Energy Nuclear Weapons Complex. ORMC’s guidance for this position comes from ISO 17025, Section 220.127.116.11.1, NOTE 1, which defines what is considered as sufficient evidence of traceability of the calibration data reported.
Data recording and reporting
As a general practice, ORMC takes data on every calibration performed. This enables us to comply with the requirements to “retain records of original observations, derived data, and sufficient information to establish an audit trail, calibration records, staff records, ...” (ISO 17025, Section 18.104.22.168). It also helps ORMC to comply with the ISO 17025, Section 22.214.171.124 requirement for having and applying a procedure to estimate the uncertainty of measurement for all calibrations and types of calibrations. Certainly the availability of data is important for many other reasons, for example, when participating in interlaboratory comparisons, retesting or recalibration of an item or correlation of results for different characteristics of an item.
If data is available, what is reported to the customer? Typically, the ORMC reports all appropriate results quantitatively unless requested otherwise. If ORMC reports specific measurement information taken during a calibration, it generally reports the average value of the measurements taken. Because uncertainties are provided with the data, it is not necessary to report all the individual data points that make up the measurement. Occasionally, a customer will need ORMC’s raw data for research or other purposes. In those cases ORMC can provide a data file as a supplement to the report, usually at an additional charge. If a simple Pass/Fail result is all a customer wants, then this is what is reported, along with the other information required by ISO 17025.
ORMC finds nothing in ANSI/NCSL Z540-1 or ISO 17025 to prohibit a laboratory from reporting Pass/Fail data. Regardless of how the data is reported, ORMC maintains all data obtained during the calibration and this information is available to the customer upon request.
ORMC provides the necessary links from which an unbroken chain of traceability can be established, and depends on the attested competency of other laboratories with which it does business to ensure the links remain unbroken. It is ORMC’s interpretation that data must be taken when performing a calibration, within the limits of the calibration method or procedure, and retained by the laboratory. The amount and type of data furnished to the customer may vary, depending on the customer’s needs.