The liquid piston provers have been widely used as the primary standard for liquid flow measurement. There are many flowmeters which can be used with the prover such as turbine flowmeters, variable area flowmeters, electromagnetic flowmeters, etc. The flowrates from the prover are measured by volumetric method. Thus, the displaced volume of water and the moving distance of the piston during measurement are the key factors. In order to receive the accurate volume, the efficient system for gaining pulses from the linear encoder is needed. Also, temperature and pressure of liquid inside the piston cylinder and the environmental conditions are involved with the measurement. Recently, the piston prover at NIMT had been upgraded by replacing the out-of-date control system and modifying the key equipments; linear encoder, PT-100 and digital manometer. Moreover, the well-known method called ‘water draw’ has been brought to verify the new system and provides the piston prover constant value. The uncertainty of the system is evaluated and reported as 0.07% (k = 2).

Results of experiments concerning humidity measurements have been presented in the paper. Integrated humidity sensors were used for the experiments, which transformed the value measured into a corresponding capacity. The structure of a measuring system was described, and the requirements concerning particular elements of the measuring track were defined. Using the regression method, an analytical equation was modeled, combining the output capacity value of the sensor with the examined humidity changes. With the use of experimental results as well as the least square method, the values for the above equation’s parameters were determined. The knowledge of coverage factor characteristics for the convolution of four selected probability distributions was used for the research.

In order to perform traceable hardness measurements using Rockwell Hardness Indenters, the indenter must conform to the requirement of ISO 6508-3 standard. The standard defines specifications for the geometric parameters for this type of indenter. Conformance to this standard is of particular importance to all calibration laboratories which operate in accordance with ISO/IEC 17025. At present there is no facility in South Africa with the capability of calibrating indenters for conformance to ISO 6508-3. This situation is being addressed through a series of studies currently being conducted at the National Metrology Institute of South Africa. The following parameters are calibrated using the µCMM. ISO 6508-3 specifies a radius of 200 µm with an uncertainty of ± 5 µm for Rockwell Hardness Indenter tips. Also specified in the ISO standard is the cone perpendicularity between the axis of the diamond cone to the axis of the indenter holder, with a specification of ± 0,03°. The last part of the ISO standard which was investigated states: “The surface of the cone and the spherical tip shall blend in a truly tangential manner.” All these parameters were measured and associated uncertainties calculated to prove conformance with ISO 6508-3 for the calibration of hardness indenters.

The efficiency of a ²²⁶Ra aqueous solution source in the radium-radon secular equilibrium against the gamma reference ionization chamber in KRISS has been obtained both by calculating from the photon energy-dependent efficiency curve of the ionization chamber and by measuring with an ²²⁶Ra standard source. The two results of calculation and measurement have showed such a good agreement that the gamma reference ionization chamber may be used to certificate the radioactivity of ²²⁶Ra aqueous solutions in the secular equilibrium and its traceability could be linked to the multi-radionuclide calibration of the ionization chamber.