4137 / Temperature (Kelvin): Tripelpunktzelle at the PTB in Berlin: EUROPA, DEUTSCHLAND, BERLIN (BERLIN, GERMANY), 2.5.2007: Triple point cell at Physikalisch-Technische Bundesanstalt PTB in Berlin, Germany. Realization of SI base unit of temperature, the kelvin, defined as 1/273.16 of the temperature of the triple point of pure water, the equilibrium among the solid, liquid, and vapour phases. The quartz glass cell contains pure water and is used for calibration of thermometers and temperature standards, which are inserted into the inner tube. - Marc Steinmetz / VISUM - Keywords: Germany, Physikalisch, Technische, Bundesanstalt, PTB, science, technology, physics, metrology, base, unit, international, system, of, units, SI, metrical, measure, measurement, standard, accurate, accuracy, lab, temperature, kelvin, thermodynamic, equilibrium, triple, point, cell, calibrate, calibration, thermo