The desiccant tube prevents moisture in the air from being sucked into the vent tube, which can cause erratic readings and sensor damage. Install the sensor so that the desiccant tube will not flood or lie in water.
The desiccant is a bright blue color when active and dry. As moisture is absorbed the color will begin to fade becoming light pink, indicating full saturation and time to replace. The life of the desiccant varies depending on the environment in which it is installed. The damper the environment or the higher the humidity, the more often the desiccant will need to be replaced. Inspect the desiccant every few weeks, until you know how it responds in your particular environment. Replacement desiccant tubes and desiccant refill bottles can be purchased from your INW or Seametrics sales representative.