The effect of dye concentration on the viscosity of water in a scanning capillary-tube viscometer

Abstract

A scanning capillary-tube viscometer (SCTV) determines the viscosity of an opaque liquid by measuring the changes in liquid level in two riser tubes. The current SCTV utilizes an optical sensor (i.e. charge-coupled device (CCD)) to measure the changes in the liquid level, where the liquid blocks the path of the light to the optical sensor. For a transparent liquid, one can use dye to make the liquid opaque. Hence, the present study investigated whether or not the addition of dye altered the viscosity of a transparent liquid such as distilled water. In this study, six different concentrations (0.5, 1, 2, 3, 4, and 7 vol.%) of dye were used. The present results demonstrated that the dye effect on the viscosity of dye–water solution was negligibly small as long as the dye concentration was less than 2 vol.%.