BS EN ISO 15091:2020 pdf free.Paints and varnishes – Determination ofelectrical conductivity and resistance.
This document specifies a method for determining the electrical conductivity and the electricalresistance of coating materials. The conductivity is usually measured for water-borne paints andvarnishes,including electrodeposition coating materials, and the resistance is usually measured forsolvent-borne paints and varnishes. If required, the resistivity of the coating material is calculatedfrom either of these measurements. The method is applicable to products having a conductivity lessthan 5 uS/cm, corresponding to a resistivity greater than 200 kQ-cm.
The conductivity of coating materials influences their processibility in the presence of an electric field.This is particularly important for electrodeposition paints and coating materials which are processedelectrostatically.
The following documents are referred to in the text in such a way that some or all of their contentconstitutes requirements of this document. For dated references, only the edition cited applies.Forundated references, the latest edition of the referenced document (including any amendments) applies.
The resistance may be determined by:
a) the measurement of the current through a sample and the voltage acting on the sample, or;
b) comparison of the measured resistance with a reference resistance.
For the current/voltage measurement,usually a constant pre-determined voltage is applied to thesample, and thecurrentis measured with a suitable measuringinstrument(e.,g.a moving-coilinstrumentor a digital instrument).The resistance is then calculated from Formula (1).See Figures 1 to 3.
To compare the resistance of the sample with a reference resistance, a bridge circuit is used in whichthe resistances are balanced so that the bridge current becomes zero. The resistance of the sample iscalculated from the ratio of the resistances of the bridge circuit.Because the bridge current is zero,errors which can result from the existence of a load on the voltage source when the voltage/currentmeasurement method is used are avoided. The only contributions to the overall measurement errorare any uncertainty in the reference resistance and any uncertainty in the adjustable resistance.See Figure 4.BS EN ISO 15091 pdf download.