Ryosuke Tasaki, Takanori Yamazaki, Hideo Ohnishi, Masaaki Kobayashi, Shigeru Kurosu
CONTINUOUS WEIGHING ON A CONVEYOR BELT WITH FIR FILTER

Today much higher speed of operation and highly accurate weighing of packages during crossing a conveyor belt has been getting more and more important in the food and distribution industries etc. Continuous weighing means that masses of discrete packages on a conveyor belt are automatically determined in sequence. Making the best use of new weighing scale called a multi-stage conveyor belt scale which can be created so as to adjust the conveyor belt length to the product length, we propose a simplified and effective mass estimation algorithm under practical vibration modes. Conveyor belt scales usually have maximum capacities of less than 80 kg and 140 cm, and achieve measuring rates of 150 packages per minute and more. The output signals from the conveyor belt scales are always contaminated with noises due to vibrations of the conveyor belt and the product in motion. In this paper an employed digital filter is of Finite-duration Impulse Response (FIR) type designed under the consideration on the dynamics of conveyor belt scales. The experimental results on conveyor belt scales suggest that the filtering algorithm proposed here is effective enough to practical applications.

Michael D Collins, Neculai Moisoi
A New Tool to Improve Fiscal Monitoring and Custody Transfer in The Oil and Gas Industry

Typically, differential pressure transmitters used for fiscal monitoring and custody transfer purposes are often calibrated with the low side open to atmosphere. If the relevant line pressure is not applied during the calibration of differential pressure transmitters, the validity of the calibration is questionable. It is widely acknowledged that the output of differential pressure transmitters changes with line pressure due to mechanical distortion of the wetted parts. Although the distortion is thought to be extremely small, the high degree of sensitivity results in a significant change of output. The main reason these devices are not calibrated at line pressures is the high cost and complexity of existing calibration standards, usually twin post piston gauges and pressure dividers. This paper gives an overview of the early development of a new differential pressure standard, more stable and accurate than the classical twin post balances. This new differential pressure standard is easy to use and the time required to perform the measurements is considerably reduced compared with the more established traditional methods. The line pressure range is 0 to 30 MPa with a differential pressure range of 0.1 to 700 kPa. The piston gauge will be described in detail including its metrological characteristics and ease of operation.

A. ELTAWIL, A. SALAMA
ESTABLISHMENT THE TRACEABILITY OF NIS PISTON-CYLINDERS FOR THE 200 MPa RANGE OF HYDRAULIC PRESSURE

Pressure balances are excellent standards for measuring pressure with acceptable uncertainty and they are widely used at the primary pressure laboratories in the world. This study aims to establish the traceability of NIS piston cylinder assemblies for the 200 MPa hydraulic pressure range by calibrating them with the smallest uncertainty. All assemblies will be traceable to a transfer standard calibrated at BNM-LNE- France using di-ethylhexyl-sebacate as the pressure medium. The consistency of all calibration data available will be investigated in order to draw conclusions regarding the realization of traceability in the 200 MPa range of hydraulic pressure by the cross float method. New values of the effective areas and the pressure distortion coefficients as will as the associated expanded uncertainties of NIS piston cylinder assemblies will be derived from the results of this study. The present study also establishes a link to the latest trilateral intercomparison in the pressure range 40- 200 MPa between NIST-USA, AIST- Japan and NIS-Egypt.

Michael Gläser
The unit kilogram, needs and experiments for a new definition

D. Peschel, D. Mauersberger, D. Schwind, U. Kolwinski
THE NEW 1.1 MN·m TORQUE STANDARD MACHINE OF THE PTB BRAUNSCHWEIG/GERMANY

Until 2003 it was impossible to perform traceable calibrations for torque measuring systems above applied torque values of 200 kN·m anywhere in the world. Up to this figure such calibrations are possible at LNE/Paris. This is despite the fact that a number of applications with considerably larger torque values are known (energy generation, shipbuilding etc.). In addition there are requests for calibrations above the largest measuring range so far available at the PTB (20 kN·m), as realised with a deadweight torque standard machine (20 kN·m TSM) acting on a double-sided lever arm supported in an air bearing. In 2002/2003, a new torque standard machine with a capacity of 1.1 MN·m was constructed and manufactured by GTM Gassmann Theiss Messtechnik GmbH in co-operation with the torque laboratory of the PTB. In 2004, initial evaluations and the analysis of the measurement uncertainty were concluded. First calibrations were already performed in May/June 2004. The machine has a vertical test axis and the effective torque is determined by means of force transducers acting on a double-sided lever arm. Parasitic bending moments and transverse forces, which cannot be entirely avoided, at the locations of the force transducers are measured by strain-gauged bending joints. These disturbances are partly controlled by additional drives and partly electronically processed to correct the measuring signal. This allows to abandon the principle so far applied – i.e. the reduction of parasitic quantities by use of metallic multiple disk couplings which are torsionally stiff and flexible in bending – and to rigidly couple the object to be calibrated. Measurement of the mechanical parasitic quantities during loading and reducing them to a negligible amount with respect to the measurement uncertainty allows the system to be used as national standard with sufficiently small uncertainty of measurement. The aim is to achieve a value of 0.1 % (k = 2) in the measuring range from 5 kN·m to 1100 kN·m. There are further requirements which call for a reduction of the measurement uncertainty in the measurement range up to 100 kN·m which will be dealt with in future. The paper gives an overview of the design, construction and first results of the investigations into the measurement uncertainty.