Temperature

TEMPERATURE LABORATORY

The Temperature Laboratory is responsible for the development of the national standards of temperature and relative humidity and has the following duties:

The realization of the International Temperature Scale of 1990 (ITS-90) on the fixed points between the triple point of Argon (-189,3442 °C) and the freezing point of Silver (961,78 °C);
The realization of the ITS90 based on Planck radiation, with the freezing point of Copper (1084,62 °C);
To assure the traceability on Temperature measurements on the measuring interval from –190 °C to 2500 °C;
Calibrate reference standards of secondary laboratories, accredited laboratories and industry;
Participate and coordinate interlaboratory comparisons;
Technical support to the legal metrology.

Get to know ongoing projects here. (link para página de projetos) aqui.

FIELD OF ACTIVITY

The domains of operation of the Temperature Laboratory with international recognition, covered by the Measurement and Calibration Capabilities registered in the BIPM database, are listed and identified with the respective symbol in the table of available services.

ITS90 Fixed Points Domain – The realization of the International Temperature Scale of 1990 (ITS-90) on the fixed points between the triple point of Argon (-189,3442 ^°C) and the freezing point of Silver (961,78 ^°C); The realization of the ITS90 based on Planck radiation, with the freezing point of Copper (1084,62 ^°C).

Contact and Non-contact Thermometry Domain – To assure the traceability on Temperature measurements on the measuring interval from –-80 °C to 1050 °C; calibration of reference standards of secondary laboratories, accredited laboratories and industry.

Hygrometry Domain- Calibration of measuring instruments of relative humidity from 10 % HR to 90 % HR.

TRACEABILITY

The traceability to SI units is achieved through the realization of the Fixed Points of ITS-90 and appropriate resistance standards.

International System Base Unit of Temperature (T)

kelvin (K) defined as:

the SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1,380 649 x 10^-23 when expressed in the unit J K^-1, which is equal to kg m² s^–² K^-1, where the kilogram, metre and second are defined in terms of h, c and Δv_Cs.

Derived unit of the International System of the temperature quantity (t):

degree Celsius (^ºC) defined by the equation:

t = T – T₀ , where T₀ = 273,15 K is the ice point. The unit of Celsius temperature unity is by definition equal in magnitude to the kelvin.

The unit of Relative Humidity quantity (UW) with respect to water:

Symbol (%) defined as follows:

The ratio of the actual vapour pressure (e) to the saturation vapour pressure (e_W) over a plane liquid water surface at the same temperature t (^ºC), expressed as percentage. This is commonly understood when the term “X percent relative humidity” is used.

External documents:

[1] BUREAU INTERNATIONAL DES POIDS ET MESURES – Supplementary Information for the International Temperature Scale of 1990 1.ª ed. Pavillon de Breteuil; Sèvres: BIPM, 1990. ISBN 92-822-2111-3.(1º)

[2] BUREAU INTERNATIONAL DES POIDS ET MESURES – Techniques for Approximating the International Temperature Scale of 1990 1.ª ed. Pavillon de Breteuil; Sèvres: BIPM, 1990. ISBN 92-822-2110-5.(2º)

[5] QUINN, T. – Temperature. Londres: Academic Press, 1983. (Monographs in Physical Measurement). ISBN 0-12-569680-9.

[4] H. Preston-Thomas – The International Temperature Scale of 1990 (ITS-90), Metrologia, 27, 3-10. Pavillon de Breteuil; Sèvres. (1990).

[5] Módulos dos guias BIPM para a EIT90:

Guide to the Realization of the ITS-90, Introduction, CCT, BIPM, 2018;

Guide to the Realization of the ITS-90, Platinium Resistance Thermometry, CCT, BIPM, 2018;

Guide to the Realization of the ITS-90, Triple Point of Water, CCT, BIPM, 2018;

Guide to the Realization of the ITS-90, Fixed Points: Influence of Impurities, CCT, BIPM, 2018.

AVAILABLE SERVICES

Get to know here available calibration services on the temperature laboratory.

International Recognition

The calibration services with international recognition, covered by the Measurement and Calibration Capabilities are listed and registered in the BIPM database.