An Investigation on the Techniques used in Force Calibration using Deadweights and Pressure Piston Gauge

537-543This paper presents two mechanisms for load cell calibrations. The first technique was to use deadweight to generate the required reference load (Applied load). The second method was to use a pressure piston gauge to generate the required calibration force. In both mechanisms, the setup and procedures are described. For verification the results of these methods were compared with international metrology institute calibration results. It was found that deadweight method is the most accurate and the piston gauge is the most realistic at high force values

An Investigation on the Techniques used in Force Calibration using Deadweights and Pressure Piston Gauge

This paper presents two mechanisms for load cell calibrations. The first technique was to use deadweight to generate the required reference load (Applied load). The second method was to use a pressure piston gauge to generate the required calibration force. In both mechanisms, the setup and procedures are described. For verification the results of these methods were compared with international metrology institute calibration results. It was found that deadweight method is the most accurate and the piston gauge is the most realistic at high force values

Establishing and characterizing a permanent magnet system for the prototype of NIS's Kibble balance

The Kibble balance experiment is used to redefine the kilogram as a unit of mass based on the Planck constant. To demonstrate and understand the basic principle of the Kibble balance, the National Institute of Standards (NIS)-Egypt has constructed a prototype Kibble balance that can measure gram-level masses with 0.01% relative uncertainty. Through the construction of this prototype, the challenges can be studied and addressed to overcome the weaknesses of NIS’s prototype. This study presents the design and construction of the prototype Kibble balance. It also focuses on the design and performance of the magnetic system, which is a crucial element of the Kibble balance. Analytical modeling and finite element analysis were used to evaluate and improve the magnet system. Several other aspects were also discussed, including the yoke’s material and enhancing the magnetic profile within the air gap of the magnet system. Over a vertical distance of 30 mm inside the air gap, the magnetic flux density was found to be 0.3 T, and the uniformity was found to be 8 x 10 -5

Validation of NIS 500 MPa hydraulic pressure measurement

500 MPa pressure is considered as the common maximum pressure in most of the National Metrology Institutes worldwide; however, validation of the uncertainty in that range required a lot of work. NIS when recognized on, 2008 guaranteed big uncertainty value above 200 MPa due to the absence of international comparison at that time. This paper summarizes the results of a validation of 500 MPa range of hydraulic gauge pressure measurements carried out at NIS. The study covers the calibration through direct comparison and through using of a pressure sensor. The paper summarized the technical work carried out at the results of measurements and the effect of these results on NIS Calibration Measurements Capability. The validation also includes the comparison between the obtained results and pervious calibration of the same piston-cylinder assembly that calibrated against the NIST primary standard

An investigation on using the falling mass technique for dynamic force calibrations

In this paper, we present an experimental setup developed for the calibration of dynamic force transducers which is based on the drop mass method. The traceability to SI units is realized through well-known mass characteristics and a reference shock accelerometer attached to that mass. Two approaches are proposed to analyse dynamic force employing a drop mass system. One approach depends on the inertial force of a falling mass while the other deals with the work-energy principle. Results of both approaches are then compared to the response of a statically calibrated force transducer. It is shown that the obtained maximum relative deviations between the response of force transducer and the first approach results are 1% while those of the second approach are 2%

Results of Hydraulic Pressure Comparison in the Range from 25 MPa to 200 MPa between NIS-Egypt and NIST-USA 1

Abstract The results of an informal pressure comparison between the National Institute of Standards and The TS was cross-floated against the laboratory MPa to 100 MPa, showed differences in the result standards (LS) of NIS and NIST at nominal pressure between NIS and NIST. These differences were 70 points of (25, 50, 75, 100, 125, 150, 175, 200) MPa. The ppm at 10 MPa, 15 ppm at 50 MPa and 9 ppm at 100 NIS laboratory standard was a pressure balance MPa; the difference at 10 MPa was larger than the with a free deformation PCA of full range of 50