Primary Standards
The Hart Scientific Super Thermometer 1575A is center stage along with several SPRT's featuring calibration traceable to the fixed points of the ITS-90 temperature scale and NIST.
The 1575A makes precision resistance ratio measurements to determine temperature with an uncertainty of ±0.002°C or less. SPRTs and PRTs generally require temperature to be calculated according to the International Temperature Scale of 1990 (ITS-90) by applying coefficients unique to the SPRT or PRT. The 1575 does these calculations automatically. The sensor coefficients are entered into the 1575 by the user and stored in non-volatile memory. Temperature is calculated in any of a variety of units including degrees Celsius (°C), degrees Fahrenheit (°F), or Kelvin (K). Once the temperature reading is obtained it is sent to the display, stored in memory, and, if necessary, written to disk or any of the output ports.
SPRT (Hart 5699) featuring calibration traceable to the fixed points of the ITS-90 temperature scale.
High Temperature Hart 5624 PRT to 1000°C
SPRT (Rosemount 162CE) (two)
TPW Hart 5901A 0.01°C (two)
A water triple point cell (0.01°C ± 0.0001) is used to correct any drift that the SPRT may experience on an ongoing basis.