The NIST Industrial Thermometer Calibration (ITC) Laboratory provides calibrations of industrial thermometers over the range from 196 C to 550 C. The different types of thermometers include liquid-in-glass (LiG), thermistors, thermocouples (<300 C), and industrial platinum resistance thermometers (IPRTs). Calibrations are performed by both comparison with an International Temperature Scale of 1990 a standard platinum resistance thermometer (SPRT) calibrated on the International Temperature Scale of 1990 and by a limited number of fixed-points. The comparison baths are liquid nitrogen ( 196 C), alcohol ( 100 C to 1 C), water (0.5 C to 95 C), oil (95 C to 275 C), and salt (275 C to 550 C). The fixed points used are the melting point of ice (0 C), the triple point of water (0.01 C), and the melting point of gallium (29.7646 C). The temperature measurement system for the reference SPRT is a commercially-available ac resistance ratio bridge, for the IPRTs and thermistors it is a dc voltmeter with a constant current source, for the thermocouples it is a dc voltmeter, and for the LiGs it is a digital video camera. All of these temperature measurement systems are integrated via three computer-controlled data acquisition systems that semi-automate calibrations. This paper presents the methods, equipment, and uncertainties associated with the calibration of industrial thermometers in the ITC Laboratory.
Proceedings Title: International Symposium on Temperature and Thermal Measurements in Industry and Science | 8th | | VDE
Conference Dates: June 1, 2001
Conference Location: Berlin, GE
Conference Title: TEMPMEKO
Pub Type: Conferences
Digitals, Industrial Thermometers, ITS-90, Liquid-in-glass, Resistance Thermometers, Thermistors, Thermocouples, Thermometer Calibrations, Thermometry