Two new miniature metallic sealed-cells containing the triple point of water, WTP (273.16K) and the triple point of mercury, HgTP (234.3156 K) have been constructed for therealization of the International Temperature Scale of 1990 (ITS-90) at the NationalInstitute of Standards (NIS-Egypt). The new cells will provide facilities for thecalibration of Capsule-type Standard Platinum Resistance Thermometers (CSPRTs). The twocells will complete a multi-cells compartment in order to calibrate CSPRTs in one singleexperiment. The multi-cells compartment contains two other cells; the triple point ofargon (83.8058 K) and the triple point of oxygen (54.3584 K) that has been alreadydeveloped and characterized before [M.G. Ahmed, Y. Hermier, Development of an adiabaticcalorimeter in the range 54 K–273 K in frame of a scientific collaboration LNE-NIS, AIPConf. Proc. 1552, 153 (2013)]. The system can calibrate two CSPRTs at once.The compartment is accommodated in an adiabatic calorimeter. With a special technique, thecalorimeter could go down to a temperature of 52 K using liquid nitrogen and specialpumping system.

A new comparison system has been constructed for the calibration of capsule-type standardplatinum resistance thermometers (CSPRTs) below 273.16 K at the National Institute ofStandards (NIS-Egypt). The system can compare two CSPRTs at once. A gold plated comparisonblock, in which CSPRTs are mounted for calibration, is made from oxygen-freehigh-conductivity copper. A description of the system and the comparison block along withthe comparison method is given. The standard uncertainty related to the temperaturecontrol of the system is estimated to be 0.04 mK. The calibrated values for CSPRTs andobtained using the comparison system are in good agreement with those obtained by thedirect realization of the low temperature fixed points of the ITS-90 within the combinedstandard uncertainty.