Makora In short, this means that traceability is established through the laboratory standards and consists of an unbroken chain of calibrations. Having two different national standards can be confusing for both laboratories and anwi therefore, we have put together a brief guide to describe the basic differences between the two standards. Z requires traceability of measurements to national standards, along with international standards or intrinsic standards. Lyle Burwell has been writing professionally since When it comes to measurement uncertainty, is more strict x Z Z differs from because it pertains only to calibration laboratories.
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The Z has been an American National Standard since Department of Defense requirements. That reaffirmation continues Z for five more years. This standard has been accepted by Mutual Recognition Arrangement as the international standard for accreditation of calibration and testing laboratories. Any laboratories seeking accreditation will be assessed to Earlier this year, the was adopted as a stand-alone American National Standard in the U. Laboratories meeting the requirements of the Z do not necessarily meet the requirements of the and some accrediting bodies no longer state accreditation to Z on accreditation certificates.
Accrediting bodies are assessing ways to accommodate labs needing compliance to both standards. If customers choose to add these elements to their requirements, their scope of accreditation can reflect compliance to the Z Part 1.
In the remainder of this article, we outline some of the importance differences between the two major standards. Under the Z, calibrations are validated through methods of internal quality control. The was written to include the requirements for both calibration and testing laboratories by demonstrating that the laboratory operates in a technically competent manner under the confines of a documented quality system producing valid results. The focuses on the competency of the legally responsible bodies providing test and calibration services.
These bodies may be independent or part of a larger organization. The philosophy of the is focused on providing competent measurement services with results that are traceable to appropriate standards. The laboratory and the client must fully understand and agree on the calibration or testing services provided.
The validity of the test and calibration results is controlled through internal quality methods. Demonstration of the competency of the laboratory can be accomplished by accreditation or other means such as interlaboratory comparisons. Z was not written for testing laboratories.
Laboratories and their customers therefore need to consider four different situations in deciding which standard to apply. Calibration Services. If the customer requires calibration services only, either standard may be applicable, though only the meets international requirements. Testing Services. For testing services, only the applies.
Calibration and Testing Services. Only the covers both calibration and testing services. Products and Services. If international customers have such requirements, they are not covered by the , but rather by ISO Calibration Due Dates The is more stringent than the Z on the placement of calibration due dates on calibration certificates and calibration labels.
Although manufacturers may designate time periods over which products should perform without degradation, the makes clear that it is the responsibility of the end-user organization to determine the appropriate calibration interval under the requirements of its own quality system. The goal of calibration interval analysis is to reduce out-of-tolerance conditions to an acceptable level based on the quality requirements of the organization.
Specifically, the calibration interval should be stated in the contract or purchase order or otherwise agreed to with the client before it is indicated on the calibration report or label. Measurement Traceability The Z requires traceability of measurements to national standards, international standards, or intrinsic standards that have been compared to other intrinsic standards, particularly those of national labs. The Z also requires statements of traceability on calibration reports.
While the Z does not specifically require traceability to International System of Units SI units, such traceability would be implied by traceability to national or international standards. The requires traceability to SI units. This traceability is established through the laboratory standards in an unbroken chain of calibrations through appropriate primary standards and may be made through national measurement standards.
The states that traceability shall be assured by the use of competent laboratories that demonstrate measurement capability and traceability. Finally, where the Z requires a traceability statement, the calls for proof of traceability.
For more information on traceability, refer to the NIST website: www. The requires a comprehensive uncertainty analysis for all calibrations under the philosophy that traceability of a measurement cannot be established without knowing the expanded uncertainty. A TAR may be stated on the calibration report, however, it must be in addition to the quantified uncertainty of the measurement. Legal Responsibility requires laboratories to be legally responsible entities.
The Z is less emphatic on this point and states that the laboratory must be legally identifiable. This is an issue of legal responsibility and accountability for the calibration work performed by the laboratory or organization. Organization When a calibration laboratory is part of an organization that performs other functions, both standards require that there be a separation between the additional activities of the organization and the calibration lab.
Confidentiality of Customer Information Both standards require documented policies and procedures to ensure the confidentiality of customer information. However, whereas the Z does not specifically address electronic storage and transmission of customer data, requires documented procedures and policies to protect the confidentiality of such electronic data. Document Control The Z includes a general statement about documentation control that is arguably ambiguous.
The is clearer, requiring written procedures for the control of all quality system documents with regards to approval, issue, review, and change. Both internal and externally generated documentation such as regulations, standards, procedures, test or calibrations instructions, drawings, software procedures, equipment specifications, and manuals are included. Job Descriptions The Z requires job descriptions for key personnel and makes reference to job descriptions for other personnel.
The requires job descriptions for managerial, technical, and key personnel and encourages job descriptions for personnel involved in calibration or testing. The details the minimum elements of job descriptions and specifies that the quality manual contain the job descriptions for the technical manager and quality manager for the lab. Corrective and Preventive Actions The Z contains a general statement about procedures for corrective actions regarding measurement discrepancies or departures from documented procedures.
The statement is contained in a list of 21 items that are to be contained in the quality manual. The excludes this list but outlines corrective action procedures. Cause analysis, implementation, monitoring, and additional audits are specifically discussed. The also requires procedures for preventive actions regarding the quality system or technical issues, whereas the Z does not address preventive actions.
Management Review An annual management review of the quality system is required by Z The review is to determine the adequacy and effectiveness of the system.
Any changes or improvements to the system should be addressed in the review. Under , management review is completed according to a predetermined schedule, which does not have to be annual. A list of the minimum elements of the review is outlined.
Internal Audits Procedures for internal audits and review are part of the quality manual requirements of Z The Z requires findings and corrective actions resulting from audits to be documented and that the individual responsible for quality should ensure that corrective actions are completed on time. No other follow-up activities are addressed. The , however, requires internal audits to cover all the elements of the quality system and that they be planned under the quality manager according to a predetermined schedule.
The also requires documentation of follow-up activities including corrective actions and their effectiveness. Personnel The Z requires sufficient laboratory personnel with the necessary technical and educational requirements for their assigned duties. Training of personnel shall be documented and kept up-to-date. Relevant training records of calibration personnel shall be available to the laboratory. The states that calibration lab managers shall ensure that personnel are competent to perform tests and calibrations.
Qualification for a specific task shall be based on demonstration of the required skills, education, training, and experience. Personnel training on the job shall be appropriately supervised. Management shall formulate goals for training, education, and skills. And authorization is required for the performance of certain tasks. Client or Customer Service Requests The Z does not require procedures for contract, request, or tender review. The , however, requires a procedure for the review and retention of all records pertaining to requests, tenders, or contracts.
The client and the laboratory must agree upon the appropriate method of calibration. And detailed records must be maintained through the entire process. Technical Records The goal of the record system identified in the Z is to retain sufficient information to repeat a calibration under identical conditions. The identity of the personnel responsible for the calibration should be part of the records and all records should be safely stored for a designated period of time.
The requires laboratories to establish and maintain a procedure for quality and technical records. The requirements of these records are specifically outlined. One major point is the requirement that laboratories maintain records of original observations with sufficient information to establish an audit trail.
Opinions and Interpretations The allows for opinions and interpretations to be documented on a test report. The laboratory is required to document the basis of such opinions or interpretations and to clearly identify the remarks in the report. The QA system requires the identification of those individuals who are authorized and considered competent to provide opinions and interpretations and to specify the extent of their capabilities.
The Z does not directly address opinions and interpretations. Conclusion: We have outlined only some of the differences in these two standards. In general, the is more prescriptive and has clarified and added to the ISO Guide 25 requirements upon which the Z Part I is based.
Some of the sections of the Z are ambiguous and subject to interpretation. Laboratories need to fully investigate these two standards and come to an understanding of their differences. No article or discussion of the differences can replace the personal knowledge of the laboratory personnel responsible for implementation of the standards in the organization.
NVLAP is currently in the process of developing the checklist for Z requirements not addressed in
ANSI NCSL Z540-1 PDF
Requirements for the Calibration of Measuring and Test Equipment Abstract This National Standard establishs the technical requirements for the calibration of measuring and test equipment. This is done through the use of a system of functional components. Collectively, these components are used to manage and assure that the accuracy and reliability of the measuring and test equipment are in accordance with identified performance requirements. In implementing its objective, this National Standard describes the technical requirements for establishing and maintaining: the acceptability of the performance of measuring and test equipment; the suitability of a calibration for its intended application; the compatibility of measurements with the National Measurement System; and the traceability of measurement results to the International System of Units SI. To find similar documents by Federal Supply Class Code: This document comes with our free Notification Service, good for the life of the document. This document is available in Paper format.
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