A water in fuel sensor is a device that detects the presence of water in a fuel system. Often used for some control function when the moisture content reaches a determined set point.
Difference between moisture and free water measurements?
Moisture in a fuel is often detected at low levels and sensors have been designed to determine an increase in moisture levels over time.
Moisture meters normally respond very slowly and are limited in their range (only measuring moisture) but free water measurements enable operators to identify when other problems have occurred such as water break out.
The sensor can measure both gradual moisture increases over time as well as the presence of free water in real time. Operators will have the added advantage of knowing when an event has occurred e.g. a sudden increase in water droplets in the fuel pipe during operation. Such measurements are taken once per second.