INFLUENCE OF GEOMETRIC UNCERTAINTIES ON THE ACCURACY OF CALCULATED CONSTANT OF THE PRIMARY CONDUCTIVITY CELL |
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| A. Mikhal, Z. Warsza |
- Abstract:
- This report presents a functional diagram of the Ukrainian primary standard of electrolytic conductivity (EC) and construction of primary four electrode conductivity cell with the calculated coupling constant. The equations for calculating the cell constant and budget of errors for calculating uncertainty are presented. The components of budget are: error due to the non-uniformity of the force lines of the electric field; the error due to accuracy of measurement standards and measuring instruments when determining length and diameter of the tube; the error due to manufacturing techniques of tubes and their assemblage. The article considered in details the error due to non- ideal profile of the central part of the tube.
The process of precision machining and quality control of the inner surface of the tube are complex and expensive procedures. The report gives an algorithm for measuring of length and diameter of the tube. Experimental data show that distortion of profile may be two types. The first type is deviation of the tube profile from the rectangle along the longitudinal section. The reason is the precession of the grinding tool. The second type is deviation of the profile of the tube from circumference in the cross section. The reason is the presence of wedge-shaped cracks on the inner surfaces of the work piece. The presence of deterministic component in the distortion of the profile leads to a significant increase in the standard deviation of the mean (SDM).
The paper presents two methods to reduce the standard deviation: the method of linear interpolation for compensation of the concaveness which occurs along the axis of the tube and the method of equivalent triangles to compensate deviations from the circle that occurs across the axis of the tube. - Keywords:
- conductivity, primary cell, geometric errors, standard deviation
- Download:
- IMEKO-TC14-2013-85.pdf
- DOI:
- -
- Event details
- IMEKO TC:
- TC14
- Event name:
- TC14 ISMQC 2013
- Title:
11th International Symposium on Measurement and Quality Control
- Place:
- Cracow and Kielce, POLAND
- Time:
- 11 September 2013 - 13 September 2013