hrvatski

First realization and measurements in the triple point of argon

As part of the development of the measurement system for the primary realization of the temperature scale (ITS-90) in the Laboratory for Process Measurements, the equilibrium state of the triple point of argon inside a hermetically sealed cell at a temperature of -189.3442 °C was successfully achieved for the first time. A cryostatic vessel filled with liquid nitrogen with manual pressure regulation was used to achieve the triple point temperature. After the initial filling, the pressure inside the cryostat was regulated by manually placing weights on the discharge valve of the nitrogen vapours into the environment. The temperature inside the argon fixed point cell was monitored with a quartz-sheathed platinum resistance thermometer connected to a high-precision resistance thermometry bridge, and the thermometer tube was filled with helium to avoid condensation. During the realization, the pressure inside the cryostat vessel filled with liquid nitrogen was measured, as well as the atmospheric pressure in the laboratory. In addition to the realization of the triple point of argon, characteristics and sensitivity of the manual pressure regulator, as well as the influence of the pressure change on the temperature inside the system were examined. The first measurements at the argon fixed point cell showed that by using the above-mentioned measuring system, it is possible to achieve the equilibrium state of the triple point with a satisfactory duration, which fulfils the first prerequisite for further development of the system. However, additional tests of the manual regulator pointed out that the existing pressure regulation is insufficiently flexible and not suitable for complete automation of the realization process. Based on the first measurement results, the necessary improvements in the form of automatic pressure regulation were determined, and work on the design and construction of the new pressure regulator has begun.

temperature, triple point of argon, cryostat, pressure regulation

nije evidentirano

engleski

First realization and measurements in the triple point of argon

As part of the development of the measurement system for the primary realization of the temperature scale (ITS-90) in the Laboratory for Process Measurements, the equilibrium state of the triple point of argon inside a hermetically sealed cell at a temperature of -189.3442 °C was successfully achieved for the first time. A cryostatic vessel filled with liquid nitrogen with manual pressure regulation was used to achieve the triple point temperature. After the initial filling, the pressure inside the cryostat was regulated by manually placing weights on the discharge valve of the nitrogen vapours into the environment. The temperature inside the argon fixed point cell was monitored with a quartz-sheathed platinum resistance thermometer connected to a high-precision resistance thermometry bridge, and the thermometer tube was filled with helium to avoid condensation. During the realization, the pressure inside the cryostat vessel filled with liquid nitrogen was measured, as well as the atmospheric pressure in the laboratory. In addition to the realization of the triple point of argon, characteristics and sensitivity of the manual pressure regulator, as well as the influence of the pressure change on the temperature inside the system were examined. The first measurements at the argon fixed point cell showed that by using the above-mentioned measuring system, it is possible to achieve the equilibrium state of the triple point with a satisfactory duration, which fulfils the first prerequisite for further development of the system. However, additional tests of the manual regulator pointed out that the existing pressure regulation is insufficiently flexible and not suitable for complete automation of the realization process. Based on the first measurement results, the necessary improvements in the form of automatic pressure regulation were determined, and work on the design and construction of the new pressure regulator has begun.

temperature, triple point of argon, cryostat, pressure regulation

nije evidentirano