Standards Traceability

This requirement is similar to that stated in clause 4.11.2 of the standard and addressed later in this chapter. The checks and rechecks required to prove that the software is capable of verifying the acceptability of product are a means of calibrating test software. However, test software does not wear or drift with age or use and so cannot be calibrated against a standard traceable to national standards. To control test software you need to consider what it is that you need to control. As a minimum you should control its use, modification, location (in terms of where it is installed), replication, and disposal. Requirements for other controls are covered in clause 4.11.2 of the standard, where they can be applied to test software. 

Type T (copper-constant) thermocouples are most applicable in steam sterilizer validation work. Their working temperature range is wide and they are resistant to corrosion in moist environments. A high grade of thermocouple wire should be chosen. Premium grades of wire accurate to as close as 0.1°C at 121°C are recommended. These must then be calibrated against a temperature standard traceable to the National Bureau of Standards (NBS). 

Calibrated or verihed at specified intervals, or prior to use, against measurement standards traceable to international or national measurement standards where no such standards exist, the basis used for calibration or veriheation is recorded. 

Calibrated periodically or prior to use to master standards traceable to the NIST (National Institute for Standards and Technology)... 

For physical quantities such as mass, volume etc. measurements are made with equipment calibrated using standards traceable to SI, such that their total contribution to the overall uncertainty is less than one-fifth of the desired overall uncertainty. 

Traceability, which is generally applied in metrology, can be illustrated by a hierarchy of standards at the top there is the national standard, traceable to the SI units, which realizes a specific unit, followed by the reference standard and the working standard. The results of measurements carried out using one of the standards of this hierarchy are comparable. In chemical measurements it is possible to transfer the metrological hierarchy of standards to reference materials (RMs) which are the standards of chemical composition. 

Keywords Amount of substance standards Chemical composition standards Traceability Third party assessment Primary reference materials... 

The reference materials have the form of pellets, globules, shot, wires or bars. They are intended for use as amount of substance standard (traceability to SI) and are applied for preparation of calibration solutions. They are available only for producer of calibration standards or for national metrology institutes. 

Much of the information in this section is taken from Reference 4. Standards play such a dominant role in everyday activities that one tends to forget that they exist. One may use a radio alarm clock, the accuracy of which is expressed through the use of standards traceable to the National Bureau of Standards (NBS). By international agreement, the time is referenced to the zero time meridian in Greenwich, outside of London. The radio operates on a frequency assigned by the Federal Communications Commission. 

Calibrations should be performed using standards traceable to certified standards if these exist. 

Those most exposed to price competition seem to be beef and dairy producers, as well as some fruit and vegetable producers. In these sectors, price is not the only competitive leverage. Certification and compliance with EU standards, traceability and residues are much more relevant for the organic market and the consumer. For example, in 2001 organic beef, fruit and vegetables were under-supplied in most EU countries, especially... 

Instrument calibrations are required at intervals based on the criticality of the instruments, instrument capability, and instrument calibration history. An instmment will also be calibrated following the repair of the instrument, following the repair of the system that the instrument is monitoring/controlling, if the repair could have affected the instrument accuracy, and/or after installing the instmment into a system. All equipment used to perform calibrations will be calibrated to standards traceable to the National Institute of Standards and Technology (NIST) or other approved standards and maintain the following ... 

Inaccurate detector calibration is one of the main problems in detector use. Conventionally, detectors are calibrated with radionuclide solution standards traceable... 

ANSI N42.22-1995 American National Standard—traceability of radioactive sources to the National Institute of Standards and Technology... 

ANSI/IEEE 1995. American National Standards Institute—Institute of Electrical and Electronics Engineers Standard N42.22-1995. American National Standard Traceability of Radioactive Sources to NIST and Associated Instrument Quality Control. Online at www.ansi.org. Viewed on September 20, 2005. 

Source Code (complied with low-level requirements and SAV architecture, conforms to standards, traceable, accurate and consistent)... 

The standards are limited by the availability of the material in the environment and can only be acquired by users once every 3 years. A number of standards are no longer available, for example, PeeDee Belemnite (PDB). As a result, laboratories must evaluate and calibrate laboratory (or working) standards traceable to the certified reference materials for day-to-day measurements. 

Verification of Calibration The calibrator is fiictory calibrated using a standard traceable to National Instimte of Standards and Technology, formerly called the National Bureau of Standards, (NBS). Attempts to verify calibrator against a glass one liter burette should be conducted at l(XX)cc/min. for maximum accuracy. The calibrator is linear throughout the entire range. 

A ten-component reference standard traceable to the National Institute of Standards and Technology (NIST) is available from Institute of Gas Technology (IGT), 3424 S. SUte St., Chicago. IL 60616. 

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