In many cases, achieving high levels of quality across the diverse activities undertaken by companies requires measurements and controls on the product or service provided. At Telecom Unitronics, we believe that the quality of these measurements depends largely on the overall quality of the calibrations or verifications of the instruments and tools used, as well as the control system for these instruments and tools.
Quality Standards
: Quality standards address the need to calibrate or verify the elements used in production that could influence the quality of the final product or service.
The International Organization for Standardization (ISO) was created in 1946 and is composed of the national standards bodies of countries in all regions of the world.
clean
development, manufacturing, and
delivery of products and services
ISO quality standards have been modified over the years to ensure quality and optimize the resources of certified or accredited companies or organizations.
The ISO 9000 standards are a set of international standards and recommendations that serve as the basis for establishing quality management systems. Currently, their most advanced versions were released in 2008 and, to adapt to usage needs, are divided into the following:
The ISO 9001 standard allows demonstrating and ensuring the quality system in projects, designs, developments, installations, manufacturing and maintenance of products or services.
The ISO 9002 standard is necessary to demonstrate the production and installation capabilities of a product or service.
The ISO 9003 standard allows for demonstrating the control capabilities of a product or service through final inspection and testing.
Companies or organizations that establish quality systems based on the ISO 9000 standards can obtain certification from authorized bodies, which, in turn, have been accredited by higher-level entities, such as the National Accreditation Body (ENAC).
The ISO 17025 standard defines the set of requirements that an analytical or calibration laboratory must meet to demonstrate its competence and its ability to produce technically valid results.
In Spain, calibration, testing, or certification laboratories that implement the ISO 17025 standard are accredited by the National Accreditation Body (ENAC), which is a member of the European Cooperation for Accreditation (ECA) and has international recognition.
Currently, Telecom Unitronics is certified according to ISO 9001, ISO 14001 (Environmental Management), and ISO 17025 standards for its calibration laboratory in the areas of optics and electricity.
Calibration.
The calibration of a measuring instrument allows us to know the "error level" of the device.
The definition of calibration according to the VIM (International Vocabulary of Metrology) is:
A set of operations that establish, under specified conditions, the relationship between the values of quantities indicated by a measuring instrument or system, or values represented by a material measure or a reference material, and the corresponding values provided by standards (VIM:93).
Therefore, calibration can only be performed on measuring instruments of any quantity (voltage, current, resistance, time, frequency, optical power, etc.) that express the measurement in the base units of the International System of Units (SI) or on reference materials.
Each measurement value recorded at a calibration point has an associated uncertainty value, which, according to the VIM, is:
A parameter, associated with the result of a measurement, that characterizes the range of values that can be reasonably attributed to the measurand.
Uncertainty indicates the range of values within which the true value of what is being measured is most likely to lie, based on the various contributions that converge in obtaining the measurement.
Calibrations have a certain traceability, which the VIM defines as:
The property of a measurement result or the value of a standard whereby it can be related to specified references, usually national or international standards, through a continuous chain of comparisons, all with specified uncertainties.
The Food Safety Committee of AECOC (Spanish Association of Commercial Coding) defines it as:
Traceability is understood as those pre-established and self-sufficient procedures that allow knowing the history, location, and trajectory of a product or batch of products throughout the supply chain at any given time, through specific tools.
In other words, traceability is provided by the laboratory or external organization that performs the calibration of the reference standards used in the calibration process of a given instrument.
The calibration results are recorded in calibration certificates, the minimum content of which must be the following:
- Identification of the calibrated equipment.
- Identification of the standards used and proof of their traceability.
- Reference to the calibration procedure or instruction used.
- Environmental conditions during calibration.
- Calibration results.
- Uncertainty associated with the
measurement.
- Calibration date.
- Signature (or equivalent) of the person responsible for calibration.
Telecom Unitronics, SA has its own calibration laboratory with calibration service for customers.
Verification
involves comparing the measurements provided by the instrument with those of calibrated equipment of equal or higher metrological quality than the equipment being verified. This ensures that the equipment measures with an error smaller than that specified by the manufacturer or smaller than that required for a given task.
Verification can be applied to measuring instruments that can be calibrated but do not require high precision, as they are used to check that products fall within certain quality or accuracy levels or that they fully comply with specific requirements. The following
cannot be calibrated: instruments that do not measure quantities (communication analyzers, frame analyzers, etc.), equipment that estimates quantities rather than measures them, and tools or implements. Therefore, these can only be verified, as they are not measuring instruments that indicate results in base units of the International System of Units (SI).
A verification is accompanied by a certificate that includes the unambiguous identification of the instrument, the date and the indication of: valid, correct or suitable, for the functions to be performed without needing to specify the results of the measurements taken.
Instrumentation Control:
The objective of controlling measuring instruments is to ensure their error level is compatible with the error level required for production.
ISO 9001 is suitable for any company working in the telecommunications sector or any other industrial sector that carries out projects, designs, developments, installations, manufacturing, and maintenance of products or services, which entails controlling the calibration or verification operations of inspection instruments. Chapter 7.6 of the standard contains the requirements that must be met in the control of the equipment used for measurements, stating that:
The organization must determine the monitoring, the measurements to be performed, and the measuring and monitoring devices necessary to provide evidence of product conformity with specified requirements.
To achieve this in a Quality System, it is first necessary to determine which measurements or verifications must be performed on each product. This determines the equipment needed for these tasks, the periods between calibrations or verifications, and the adjustments to be made as a result of the results obtained.
Organizations can verify or calibrate their measuring instruments themselves (internal calibration) or outsource the service to specialized companies (external calibration). If internal calibration is chosen, the organization must have the necessary personnel and infrastructure for its proper execution and, at a minimum, externally calibrate the instruments used as standards or references.
Frequency of Calibrations or Verifications:
Equipment must be calibrated or verified at a frequency determined by the relationship between the required accuracy of the measurements and the drift of the instruments used, ensuring that the drift between two calibrations is less than the required accuracy.
Since the instrumentation is selected based on accuracy requirements, the manufacturer's recommended frequency is generally used. However, it is advisable to verify the instrument drift between calibrations to adapt them to actual needs. In some cases, this will allow us to increase the calibration period, while in others, it will be necessary to shorten it to meet the requirements.
Thus, in the Fiber Optics sector, for example, the most common instruments that must be calibrated are:
- Optical power meters.
- Light sources.
- Optical time-domain reflectometers (OTDRs).
- Optical spectrum analyzers.
- Attenuators.
- Chromaticity dispersion and PMD meters
- Etc.
An example of equipment or instruments that only need to be verified could be the following:
- Fiber optic fusion splicers.
- Traffic detectors.
- Tools.
- Etc.
Specifically, Telecom Unitronics, SA offers calibration and verification services in the Fiber Optics, Electrical, Low Frequency, and Radio Frequency sectors. Furthermore, it holds ENAC accreditation for calibrating measuring equipment in the Electrical, Low Frequency, and Fiber Optics sectors.
Author:
Pedro Notario, technical director of Telecom Unitronics, SA.
