The Hygrophil F (photo) uses a patented Fabry-Perot interferometer principle to measure trace moisture in natural gas. The sensor element of the moisture sensor type L1661 is made of a multiple layers of optically high-reflective and low refractive materials. Pores with a diameter in the tenth of a nanometer range are generated by means of a special manufacturing process. Water molecules of the medium to be measured are absorbed into these pores and change the properties of the optical filter, so that the light passing into the measuring layer undergoes a wavelength shift that is proportional to the moisture content. This is evaluated with a polychrometer and allocated to a dew point. With this procedure, a dew point measurement range of between –80 and 20°C at a precision of ±1°C is realized. It can be used directly in the pipeline under a pressure of up to 200 bars. — Bartec Benke GmbH, Reinbek, Germany
www.bartec-benke.de Gerald Ondrey