True Blue® Series GYW flow indicators are designed to indicate the presence or clarity of high purity or corrosive liquid in a piping system. For use with ultrapure liquids or chemicals compatible with acrylic. O-ring seals are used on Series GYW indicators allowing them to seal at extremely low pressures as well as high pressures. GYW flow indicators are full ported, eliminating any possible flow resistance. Pipe sizes are 1-1/2" through 8" NPT (40 mm through 200 mm). An optional fluttering device is available.