Sensors used in dirty environments often require regular cleaning. For example, oxygen sensors used in carburizing furnaces must frequently be purged (or in industry terms “burned off”) to remove soot buildup from the process.
The traditional means for purging such sensors is to flow air into the space between the sensor's protective outer sheath and its inner sensor element until that air saturate the tip (active sensor element) and burns the soot deposits.
This process can take significant time (1-2 minutes) and the sensor takes up to thirty minute to recover and read correctly again owing to the large build-up of air or within the probe sheath.
Previously, techniques used a “focused” burn-off design. In this design, a single small tube carried the burn-off air directly to the tip of the probe. The techniques dramatically reduced the volume of air needed to saturate the tip, thereby cleaning it.
Consequently, improved sensor purge systems are needed.