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<p class="Abstract"><span lang="EN-US">The aim of this study was to fabricate a torque transducer that has two measurement signals in order to simultaneously measure torque value and check its stability. The transducer has two sensing bodies aligned in the same measurement axis. The first sensing body was designed to be a measurement signal and the second sensing body was designed to be a check signal. The capacity of the check signal was designed at least two times larger than that of the measurement signal. Transducers with various capacity ratios of check signal and measurement signal with ratios 2:1, 3:1 and 4:1 were fabricated. To confirm the assumption that the fabricated transducers are able to check stability by themselves, they were overloaded from 100 % to 800 % of their capacity. The experimental results showed that the function ratios of the check signal and measurement signal corresponds with the stability measured by a torque standard machine. Thus it can be used to predict stability. Stabilities of the check and zero signals are used to find the appropriate capacity ratio. It was found that the stability of check and zero signals showed drift caused by overload. Therefore, the capacity ratio should be designed at least 3:1 for transducers made of steel and 2:1 for transducers made of aluminum. A prototype of a torque transfer wrench was also made according to the concept of the torque transducer with check standard combination. Experimental results corresponds with results of the torque transducer. It could also check the stability itself.</span></p>

There are four major uncertainty components to be considered when performing mass comparisons. They are uncertainties of weighing process, reference weight used, air buoyancy, and mass comparator. The systematic effect of air buoyancy can be greatly reduced if the air density and the densities of the test and reference weights are known. This paper will emphasis on the uncertainty due to air buoyancy correction only. To calculate the uncertainty of air density correction, partial derivatives of temperature, barometric pressure and humidity must be performed. In this paper, two methods for partial differentiation of air density components are discussed.

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