Certifying precision platinum resistance thermometers

Individual calibration has become essential for working platinum resistance thermometers, particularly to provide errors of not more than 0.01°C in order to increase the accuracy and reproducibility in temperature measurement and control in advanced technology in microelectronics, bioengineering, and other areas. Such calibration can at present be provided only by working standards for the temperature unit held by territorial bodies under the USSR State Standard Commission. Existing methods of reproducing and transmitting the temperature unit show that such equipment can be based on the reference phase-transition points for pure substances to give the required simplicity, stability, and minimum equipment volume and cost. The stability in the melting points enables one to check working platinum thermometers with a range 0-630°C with an error of not more than 0.01°C. Under industrial conditions, it is important to check narrow-range thermometers for the range 0-100°C with an error of not more than 0.01°C. It is best to use the gallium melting point as reference.