Electrically conductive fluid surface tension measurement - uses electrical contacts to record flow through capillary tube

摘要

Gas at constant pressure is blown into the fluid through a capillary tube. The rate of flow of air and the size of the bubbles is a function of the surface tension of the fluid. The bubbles are guided into a funnel and electrodes fixed across a known diameter record the presence or absence of the conducting fluid and hence measure the gas flow. Alternatively the capillary outlet may be downward and the electrodes attached directly across the outlet. The measurement can be used as an indirect measurement of concentration. The tube may be made of glass, metal or plastics with an inner diameter from 5 to 8 mm. The bubbles are initially spherical and become elongated as they enter into the narrowed section of the measurement tube.