National Metrology Institute (NMI)
Goals and Objectives
The National Metrology Institute shall provide its clients and stakeholders with metrology services that meet international standards. This shall be achieved through:
We are committed to ensuring that SIRDC’s National Metrology Institute signifies reliability, accuracy and competence
Areas of Collaboration
Current Research Areas
Products and Services
SIRDC-NMI Accredited Laboratories
Measurements are so often taken for granted we sometimes do not appreciate the grand importance measurements play in our lives. On a baseline level, measurements fall into the categories of weight, area, volume, length, temperature etc. While we look at these various categories as difficult forms of mathematical measurements, a closer examination of things we do in everyday life reveals their clear importance.
Mass Metrology Laboratory
Mass metrology is the science and practice of mass measurement. It is one of the most measured parameter in science, commerce and industry. Mass is generally defined as the quantity of matter a body contains. Mass can be measured using a suitable balance or scale. The SI unit of mass is a kilogram. A kilogram is defined as the mass of the international prototype kilogram kept in France at International Bureau of Weights and Measures (BIPM) which is the International Bureau of Measurement Standards. This is a cylinder of height 39 mm and diameter 39 mm made of a Pt-Ir. alloy comprising 90% platinum and 10% iridium with a density of approx. 21.5 g/cm3.
SIRDC- NMI has a mass metrology laboratory that meets international standards. The role of SIRDC-Mass Laboratory is to acquire and maintain mass standards and provide traceability to Zimbabwean industry by calibrating their mass pieces and balances/scales. The laboratory has equipment that can control environmental conditions such as humidity, pressure and temperature which are contributing factors to the accuracy of a measurement. The laboratory has recently acquired very accurate mass pieces that are used to calibrate other mass pieces and balances/scales used in industry.
To enable reliable product/service acceptance on the international scene the SIRDC sought accreditation of NMI laboratories to ISO/IEC 17025. ISO/IEC 17025 is the global quality standard for testing and calibration laboratories. The mass laboratory is staffed with well educated and competent personnel that can operate mass equipment. Accurate mass ensures global competitiveness and acceptance of products and services through accurate, reliable and traceable measurements. Mass metrology is applied in science, commerce and industry for example at Grain Marketing Boards, health care centres, manufacturing companies, universities and research centres.
Volume Metrology Laboratory
Volume Metrology is the science and practice of precision volumetric measurements. The basic unit of volume in the metric system is litres. Volume measurement is an important step in most industrial and analytical measurement operations. Volume instruments like volumetric flasks, micropipettes, measuring cylinders, etc., are used in many fields like chemistry, medicine, biology and pharmacy.
In mining volume measurement play an important role in the assaying laboratories where reagents to ascertain the presence of certain minerals in ores are prepared using volumetric measures such as volumetric flasks, measuring cylinders, burettes, pipettes etc. In the medical field measurements of blood quantities for blood samples are done volumetrically using instruments such as micropipettes. In agriculture volume measurements are also very important especially when irrigation water is used, a farmer may want to know the amount water needed to irrigate his whole field per week for instance. City councils also need to measure the volume of water in their water treatment plants. In industry flow meters are sometimes used to measure volumes of liquids. Volume measurements need to be done accurately from micro-litres in a medical laboratory to mega-litres in an irrigation or water treatment system. Laboratories and industry must ensure that results obtained using volumetric measuring instruments are reliable. In order to reduce and identify possible errors in liquid handling, it is necessary to calibrate the volume instruments using the correct methods. Calibration must be done regularly to ensure that measuring instruments remain within the required tolerances. Calibration of volume measuring instruments is done by a National Metrology Laboratory or other calibration laboratories. A National Metrology Laboratory in a country maintains standards of the highest accuracies with many other laboratories deriving their traceability from it.
Dimensional Metrology Laboratory
Dimensional Metrology is the science and practice of measurement of size (length), shape, angles, surface texture (roughness) and form (roundness, cylindricity, parallelism, conicity, runout etc). Dimensional measurements are traceable to the International System (SI unit) of length, the metre. SIRDC’s Dimensional Laboratory is the highest echelon Length laboratory in Zimbabwe. The laboratory was accredited to ISO 17025 by the SANAS/SADCAS twining arrangement on 15 March 2012. Making it the first accredited Dimensional Calibration Laboratory in the country.
SIRDC NMI’s Dimensional Laboratory has Calibration and Measurement Capabilities (CMC) that are recognized worldwide. The CMC claims were validated through Inter-laboratory comparisons conducted with regional and international laboratories since the year 2010. SIRDC- NMI operates a state-of-the-art dimensional metrology laboratory. End standards (gauge blocks and length bars ) widely used in industry and lower echelon Calibration laboratories for calibration of dimensional instruments and setting of machines are calibrated by SIRDC NMI using comparators with one nanometre resolution (a billionth of a metre).
Dimensional metrology is important when reverse engineering products. No product can be reverse engineered without knowing its dimensions. Dimensional metrology is also always involved at the design stage during the manufacturing stage and at the inspection stage of every product. It has been generally accepted that the level of technological and industrial development of a country is judged by the status of metrology in that particular country. It is essential therefore that dimensional measuring instruments used in science, industry and society should be calibrated against standards of high accuracy traceable to National Standards or SI units of length.
Temperature Metrology Laboratory
Temperature is one of the most widely measured parameter in the world. It is a basic fact of physics that materials are affected by changes in temperature. Most enzymes have optimum activity at 40 °C, above which they are denatured; tobacco farmers kiln their leaves at a certain temperature in order to obtain quality golden leaf while miners assay their metals at 1200°C in order to melt the precious material completely for further extraction. Therefore it becomes imperative that temperature for various materials, environments, process plants, farming environment, medical laboratories, pharmaceutical laboratories, manufacturing and testing laboratories to include but a few be monitored to ensure reliable and quality products.
Temperature measuring instruments and control systems are therefore necessary and control limits for acceptable working temperature ranges within a specific process should be determined. Regular calibration of temperature measuring equipment and control systems, be it temperature cabinets, heat treatment chambers, pre-test conditioning units thermometers or temperature controllers, provide assurance that test data is valid and processes are properly controlled.
The SI unit of temperature is the Kelvin. It is defined as the fraction of 1/273.16 of the thermodynamic temperature of the triple point of the Vienna Standard Mean Oceanic Water (VSMOW). All temperature measurements should be traceable to the SI unit. The triple point of water is the primary standard in thermometry. National Metrology Institutes are the custodians of the national measurement standards and should maintain the highest standards in terms of accuracy and disseminate measurement traceability to the nation. The triple point of water alone as a standard is not a clear representation of the whole range of temperature that is measured hence there is need for an interpolating scale that substitute the definition of the Kelvin in some stated ranges. The ITS 90 is the internationally recognised temperature scale that links the various temperature ranges to the definition of the Kelvin. It comprises fixed points. These are sealed or open cells that contain pure substances and the temperatures are realised at melting, freezing and triple points of the substances. The fixed points, just like the water triple points are primary standards in thermometry.
Zimbabwe through SIRDC-NMI is a proud owner of the Water Triple point Cell and Maintenance apparatus as well as part of the ITS 90 fixed points which are Mercury Triple Point (-38.8344 ⁰C), Tin Freeze Point (231.928 ⁰C) and Aluminium Freeze point (660.323 ⁰C). The fixed points provide reliable temperatures and calibrations at the fixed point results in a lower uncertainty to the instruments being calibrated. The calibrations at the fixed points require great competence through training as well as rigorous peer review. Our achievement of the ISO 17025 accreditation as well as Associate membership to the General Conference on Weights and Measures (CGPM) and SIRDC NMI’s signatory status to the International Committee for Weights and Measures Mutual Recognition Arrangement (CIPM-MRA) testifies our competence as all the processes call for a sound quality management system as well as a team of deemed competent personnel.
SIRDC-National Metrology Institute Temperature Department provides its clients with accredited calibration service which is internationally recognised through its adherence to ISO/IEC 17025 of 2005 and also the associate membership to the CGPM status. The quality system requires that an operating laboratory be technically competent in terms of personnel and equipment. With the equipment of the highest level of accuracy in the nation and of equivalence to the region and internationally, SIRDC- National Metrology Institute Temperature Laboratory is surely the backbone of temperature measurements in the country.
Four NMI Laboratories are accredited as indicated in the table below by the South African National Accreditation System (SANAS) and the SADC Accreditation Service (SADCAS)/SANAS Twinning Partnership Arrangement.
Zimbabwe through the National Metrology Institute (NMI) became an Associate of the General Conference on Weights and Measures (CGPM), which is the Secretariat of the Metre Convention (www.bipm.org ), on 14 September 2010.
To fulfill the criteria for the CGPM Membership, the NMI had to establish a solid Quality Management System based on the ISO/IEC 17025 International Standard and requisite technical competence in various fields of metrology which were peer reviewed by technical experts from other National Metrology Institutes.
The National Metrology Institute is a member of the Intra-Africa Metrology System (AFRIMETS) www.afrimets.org and also member of the SADC Cooperation on Measurement Traceability (SADCMET) www.sadcmet.org .
On 14 January 2011, the National Metrology Institute (NMI) signed the International Committee for Weights and Measures (CIPM) Mutual Recognition Arrangement (MRA) www.bipm.org . The CIPM MRA is a Mutual Recognition, by all signatories to the arrangement, of Measurement Standards used by the NMI as National Standards and it also recognizes Calibration and Measurement Certificates issued by the NMI.
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