Cell constant of the tetrapolar conductivity cell

1990 ◽  
Vol 28 (6) ◽  
pp. 587-590 ◽  
Author(s):  
C. Littwitz ◽  
T. Ragheb ◽  
L. A. Geddes
Keyword(s):  
Cell Constant ◽  
Conductivity Cell

scholarly journals Geometric part of uncertainties in the calculation constant of the primary four electrode conductivity cell.

ACTA IMEKO ◽  
2015 ◽  
Vol 4 (2) ◽  
pp. 18 ◽  
Author(s):  
Alexander Mikhal ◽  
Zygmunt Warsza
Keyword(s):  
Standard Deviation ◽  
Electric Field ◽  
Linear Interpolation ◽  
Electrolytic Conductivity ◽  
Measuring Instruments ◽  
Cell Constant ◽  
Error Budget ◽  
Accuracy Of Measurement ◽  
Manufacturing Techniques ◽  
Conductivity Cell

The paper presents the construction of a primary four electrode conductivity cell with calculated constant for the Ukrainian primary  standard of electrolytic conductivity (EC). The equations for calculating the cell constant and the error budget for calculating uncertainty are presented. The components of the budget are: errors due to the non-uniformity of the force lines of the electric field; errors  due to the accuracy of measurement standards and measuring instruments for determining length and diameter of the tube; and  errors due to manufacturing techniques of tubes and their assemblage. The article considers in detail the errors due to the non-ideal profile of the central part of the tube. Two methods to reduce the standard deviation are given: the method of linear interpolation for  compensation of the concave form which occurs along the axis of the tube and the method of equivalent triangles to compensate for  deviations from a circle that occur across the axis of the tube.

Micro-flowcell conductometric sweat analysis for cystic fibrosis diagnosis

2000 ◽  
Vol 37 (3) ◽  
pp. 399-407 ◽  
Author(s):  
H Lewis Webster ◽  
Carmelo G Quirante
Keyword(s):  
Power Supply ◽  
Time Interval ◽  
Sweating Rate ◽  
Sensor Cell ◽  
Sweat Testing ◽  
Small Holders ◽  
Flow Through ◽  
To Receive ◽  
Conductivity Cell ◽  
Sweat Tests

This paper describes a device specifically designed to facilitate neonatal sweat testing. The components are sized appropriately for attachment to the limbs of newborns. Iontophoretic electrodes, with pilocarpine gel inserts, are latched into small holders attached by straps to the limb. The holder at the anodic site remains in place to receive and align the sensor cell, which uses a conical collecting surface to channel the sweat directly and anaerobically from the sweat ducts to the continuous flow-through conductivity cell within its body. A crib-side analysis unit incorporates an iontophoretic power supply and displays a continuous readout of sweat electrical conductivity. The average conductivity during a specific time interval and the initial sweating rate are automatically displayed. The method, which simplifies sweat tests, is currently being assessed in three neonatal clinical trials to test its ability to reduce test failures in the newborn due to insufficient sweat.

scholarly journals About uncertainties in practical salinity calculations

Ocean Science ◽  
2011 ◽  
Vol 7 (5) ◽  
pp. 651-659 ◽  
Author(s):  
M. Le Menn
Keyword(s):  
State Of The Art ◽  
Conductivity Ratio ◽  
Real Analysis ◽  
Error Sources ◽  
Current State ◽  
Laboratory Calibration ◽  
Temperature And Pressure ◽  
Conductivity Cell ◽  
Temperature Depth

Abstract. In the current state of the art, salinity is a quantity computed from conductivity ratio measurements, with temperature and pressure known at the time of the measurement, and using the Practical Salinity Scale algorithm of 1978 (PSS-78). This calculation gives practical salinity values S. The uncertainty expected in PSS-78 values is ±0.002, but no details have ever been given on the method used to work out this uncertainty, and the error sources to include in this calculation. Following a guide published by the Bureau International des Poids et Mesures (BIPM), using two independent methods, this paper assesses the uncertainties of salinity values obtained from a laboratory salinometer and Conductivity-Temperature-Depth (CTD) measurements after laboratory calibration of a conductivity cell. The results show that the part due to the PSS-78 relations fits is sometimes as significant as the instrument's. This is particularly the case with CTD measurements where correlations between variables contribute mainly to decreasing the uncertainty of S, even when expanded uncertainties of conductivity cell calibrations are for the most part in the order of 0.002 mS cm−1. The relations given here, and obtained with the normalized GUM method, allow a real analysis of the uncertainties' sources and they can be used in a more general way, with instruments having different specifications.

scholarly journals About uncertainties in practical salinity calculations

2009 ◽  
Vol 6 (3) ◽  
pp. 2461-2485 ◽  
Author(s):  
M. Le Menn
Keyword(s):  
State Of The Art ◽  
Actual State ◽  
Conductivity Ratio ◽  
Real Analysis ◽  
Laboratory Calibration ◽  
Temperature And Pressure ◽  
Conductivity Cell ◽  
Temperature Depth

Abstract. Salinity is a quantity computed, in the actual state of the art, from conductivity ratio measurements, knowing temperature and pressure at the time of the measurement and using the Practical Salinity Scale algorithm of 1978 (PSS-78) which gives practical salinity values S. The uncertainty expected on PSS-78 values is ±0.002, but nothing has ever been detailed about the method to work out this uncertainty, and the sources of errors to include in this calculation. Following a guide edited by the Bureau International des Poids et Mesures (BIPM), this paper assess, by two independent methods, the uncertainties of salinity values obtained from a laboratory salinometer and Conductivity-Temperature-Depth (CTD) measurements after laboratory calibration of a conductivity cell. The results show that the part due to the PSS-78 relations fits is sometimes as much significant as the instruments one's. This is particularly the case with CTD measurements where correlations between the variables contribute to decrease largely the uncertainty on S, even when the expanded uncertainties on conductivity cells calibrations are largely up of 0.002 mS/cm. The relations given in this publication, and obtained with the normalized GUM method, allow a real analysis of the uncertainties sources and they can be used in a more general way, with instruments having different specifications.

scholarly journals Vaccinium gaultherioides: Another insight into water relations of alpine dwarf shrubs

2015 ◽  
Vol 2 ◽  
pp. e004 ◽  
Author(s):  
Andrea Ganthaler ◽  
S. Mayr
Keyword(s):  
Growth Form ◽  
Current Knowledge ◽  
European Alps ◽  
Hydraulic Parameters ◽  
Turgor Loss Point ◽  
Dwarf Shrubs ◽  
Hydraulic Safety ◽  
Conductivity Cell ◽  
Osmotic Properties ◽  
Insight Into

Dwarf shrubs exhibit different requirements for a safe and efficient water supply compared to trees due their basitonic branching and low growth height. Though, only few studies dealt with the hydraulics of this growth form. Here we report key hydraulic parameters (vulnerability to drought-induced embolism, xylem hydraulic conductivity, cell osmotic potential, potential at turgor loss point) and related wood anatomical traits for Vaccinium gaultherioides, a wide-spread species in the European Alps. The results affirm the current knowledge, by indicating a relatively risky hydraulic strategy with low hydraulic safety compared to alpine trees and osmotic properties connected to the species’ soil humidity requirements.

scholarly journals Numerical Simulation of Natural Convection in a Transient Short-Hot-Wire Thermal Conductivity Cell

Netsu Bussei ◽  
2008 ◽  
Vol 22 (4) ◽  
pp. 217-222 ◽  
Author(s):  
Peter L. Woodfield ◽  
Jun Fukai ◽  
Motoo Fujii ◽  
Yasuyuki Takata ◽  
Kanei Shinzato
Keyword(s):  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Natural Convection ◽  
Hot Wire ◽  
Transient Short Hot Wire ◽  
Thermal Conductivity Cell ◽  
Conductivity Cell
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