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Electricity and Magnetism


NMISA Temperature and Humidity section has the responsibility, the technological facility as well as the expertise to make accurate temperature and humidity measurements. The temperature laboratory maintains and disseminates the International Temperature Scale of 1990, ITS-90 while the humidity laboratory maintains the national measurement standards of humidity in South Africa.

Temperature:

  • Equipped with number of fixed point cells for ITS-90 temperature scale realization ranging from Argon (Ar) to Copper (Cu) point
  • Accredited to calibrate platinum resistance thermometer (-196 °C to 660 °C), thermocouple (-80 °C to 1555 °C), radiation thermometer (0 °C to 1600 °C), thermistors (0 °C to 60 °C), liquid in glass thermometers (-25 °C to 280 °C) and radiation thermometers (0 °C to 600 °C
  • Equipped with high resolution resistance bridges and voltmeters for primary and secondary calibration services
  • Equipped with different heat sources (i.e. stirred liquid bath, furnace, thermogauge etc.) for different temperature range measurements
  • Equipped with standard platinum resistance thermometers and linear pyrometer for disseminating ITS-90 temperature measurements
  • Conduct research on new temperature measurement methods
  • Participates in international comparisons to validate national standards
  • Represents NMISA internationally and actively participates in the BIPM Consultative committee for thermometry (CCT) working group activities
  • Participates in regional metrology body temperature activities (i.e. AFRIMETS TC-T and APMP TC-T
  • Provide technical assistance for SANAS STC activities in the country

Humidity:

  • Accredited to calibrate relative humidity (5 %rh to 95 %rh, over temperature range 5 °C to 60 °C) and dew point temperatures (-75 °C frost point to +20 °C dew point)
  • Equipped with chilled mirror hygrometers and a flow mixing generator for dew point temperature measurements
  • Equipped with thermo-hygrometers and temperature and humidity variable chamber for relative humidity measurements
  • Participates in international comparisons to validate national standards
  • Provide technical assistance for SANAS STC activities in the country

The temperature laboratory provides the following calibration services

  • Platinum resistance thermometers (SPRT/PRT)
  • Thermocouple (noble or base metal)
  • Hot plates
  • Surface probes
  • Liquid in glass thermometers
  • Digital thermometers
  • Thermistors
  • Radiation thermometer

The humidity laboratory gives the following calibration services:

  • Dew-point hygrometer
  • Relative humidity hygrometer
  • Saturated salt solution
  • Data loggers

Development Projects

  • Developing measurement standards for thermo-physical properties of materials
    • The NMISA temperature and humidity section will investigate the feasibility of developing national measurement standards for thermo-physical properties of materials, including thermal conductivity, thermal diffusivity, thermal transmittance, heat capacity, thermal expansion and emissivity.
    • The section's capability to provide traceability to temperature and humidity measurement can be exploited to develop a national measurement standard for thermal properties measurement. Thermal properties measurement capability development will be beneficial in the energy crises alleviation of the country.
    • This project is linked to Green Economy Measurement Tools and Measurement for Manufacturing Competitiveness cross cutter projects
  • Developing high radiometric temperature measurement capability
    • Developing accurate temperature measurements capability using radiation thermometer above copper point is essential in thermometry and radiometry. The extrapolation of the temperature scale to higher temperatures limits the principal uncertainty of the temperature scale. A research on eutectic materials that can alleviate this problem has been going on for quite some time in the other parts of the world. NMISA temperature section would like to embark on such kind of research.
    • Different eutectic materials will be investigated that can have the potential to act as fixed point to a temperature range of 3000°C. This will allow minimizing the uncertainty of measuring a radiometric temperature to a higher scale. The project will allow NMISA to be capable of high temperature measurement with low uncertainty.
    • This project is linked to Green Economy Measurement Tools and Measurement for Manufacturing Competitiveness cross cutter projects

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