The SA1W water sensor features a measuring system designed especially to detect water-containing liquids. In conventional sensors (e.g. through-beam photoelectric sensors) the light emitted by the light source passes through the transparent liquid to the receiver, as a result of which the liquid is not detected. In the SA1W water sensor, on the other h&, the transmitter emits a light beam at a wavelength corresponding to the oscillation of the water molecules. The light is absorbed by the molecules & does not reach the receiver, so the liquid is detected.