9762 papers found
This paper describes the procedure, employed by Inmetro Mass Laboratory, to determine the volume of reference mass standards submultiples of kilogram by subdivision method using a volume comparator which uses a special fluid as hydrostatic fluid. The results obtained were validated by the use of a check standard confirming that the procedure is suitable.
This paper presents a hydrostatic weighing apparatus (HWA) for the density determination of weights in the range of 2 kg to 10 kg including 1 kg. The measurement is based on Archimedes’ principle by using 1 kg sphere as a solid density standard to determine the density of the reference liquid. The HWA consists of a precision balance, a immersion pan, reference weights, a weight carrier, a sample carrier, a reference liquid, a thermostat, and a controller for stepping motors. The reference weights with capacity of 1 kg, 2 kg, 2 kg, 5, kg, and 10 kg are designed and installed to be weighed at...
In NIM, it has already set up the volume determination system from 20 kg to 1 g. But regarding the weights from 2 kg to 20 kg, it is taken method A3 in OIML R111 to measure the volume of weights. Comparing the other two methods mentioned in OIML R111 and the volume comparator VC1005 at mass lab in NIM, the measuring accuracy couldn’t meet the requirements of national secondary standard weight set. A new volume measuring system is being set up at mass lab in NIM, to replace the old mechanical system. There are two working positions not only in the liquid but in the air as well. The weighing...
For the dissemination of this quantity torque standard systems are normally operated manually, originating high consumption of man-hours in the development of a calibration. This work presents the control and characterization of a Torque Transfer Calibration System and the benefits of the automatic control system.
The ISO 6789:2003 standard is widely used as technical document for calibrations of hand torque tools, but it does not require any statements about uncertainties of calibration results. Nevertheless, according to GUM it is necessary to report a complete measurement result including its uncertainty. In this paper, a proposal is given on how to estimate measurement uncertainties of ISO 6789 calibration results taking into account various influencing quantities.
For the dynamic calibration of torque transducers, a calibration device has been developed. This paper describes the model of the measuring device and methods for the determination of its model parameters. The modelling of the calibration set-up is required for the identification of the corresponding model parameters of the torque transducer under test. These parameters describe the transducer's dynamic behaviour. Measurement methods and devices for the determination of mass moment of inertia and torsional stiffness are explained. This research is part of EMRP JRP IND09 - "Traceable Dynamic...
Inter-laboratory comparison of reference torque wrench calibration was conducted between NMIJ and PTB using a torque transducer in the form of a torque wrench, "TTS/3kNm", as a transfer device. Although the rated capacity of the transducer is 3 kN·m, the calibration range of from 200 N·m to 2 kN·m was selected. Each loading time schedule used in daily calibration was also adopted in this comparison. Calibration results obtained by both laboratories coincided with the range of uncertainties.
A 10 N·m dead weight torque standard machine (10- N·m-DWTSM) has been developed and evaluated since 2006. The main parts of the moment arm in the 10-N·m-DWTSM are made of low thermal-expansion alloy (Super Invar). It is known that parts made of Super Invar vary in length with age. In this study, the moment arm length was recalibrated using a 3D coordinate measurement machine. As a result, the moment arm length was found to have lengthened by an average of 6.3 µm in five years. Also, the relative expanded uncertainty of torque, W tsm , realized by the 10-N·m-DWTSM was revaluated in a range...
Several simple methods to test the humidity influence on the sensitivity of torque transducers are examined. Their suitability for use in calibration laboratories is discussed. A comparison to former determinations of the humidity effect with extensive methods yields humidity coefficients of the same order.
The adsorption layers on the surface of silicon artifact have been determined experimentally as a function of relative air humidity in the range of 0.07 < h < 0.73 using gravimetric method. For the purpose of this work 1 kg silicon sorption artifacts were fabricated, which have same surface finish, material properties but with very different surface area of 507.8 cm2. In this experiment ultra precision mass comparator and special humidity control unit were used. The adsorption isotherm of water vapor on the silicon surface with R z < 26.6 nm measured and sorption behavior of silicon surface...