This application uses a pipe-mounting Capacitive Liquid-level Sensor that is not affected by the color of the pipe, the color of the liquid, or foams on the liquid surface. ?This Sensor allows you to detect chemical liquid levels without being affected by the color of the pipe, the color of the liquid or foams on the liquid surface. Two models are available, one for pipes with a diameter from 8 to 11 mm and one for pipes with a diameter from 12 to 26 mm.