BS EN ISO 9455-3:2020 pdf free.Soft soldering fluxes - Test methods.Determination of acid value, potentiometric and visual titration methods. BS EN ISO 9455-3 A prepared, weighed sample of the flux is dissolved in a suitable solvent. The resulting solution is titrated with standard tetrabutyl ammonium hydroxide solution, using a glass electrode, the pH or mV readings being recorded simultaneously. From...