Two-fold sensor approach for N[O.sub.x] reduction - technology - Brief Article

Diesel Progress North American Edition, August, 2003

Partially in response to the Oct. 1, 2002, EPA "pull ahead" emissions standards, but also reflecting the increased need for overall low exhaust emissions in the future, Kavlico, Moorpark, Calif., has developed a two-fold sensor approach to reducing the formation of N[O.sub.x] emissions for on-highway vehicle applications.

Fluid level measurements are important for engine manufacturers targeting urea/water-based selective catalytic reduction (SCR) systems, Kavlico said. Injecting urea into the exhaust stream has been shown to reduce the formation of N[O.sub.x]. To support this approach to emissions control, Kavlico has developed two sensors for urea level monitoring and measuring.

The first sensor measures the changes in fluid level by monitoring dielectric change. The change in dielectric occurs due to the influx of contaminants into the system thereby changing the dielectric output. The sensor then provides a proportional voltage output to urea fluid level. The sensor utilizes Kavlico's ceramic capacitive technology. The design incorporates all stainless steal wetted parts due to the caustic nature of the media environment.

The second sensor actually measures the pressure of the fluid and provides a proportional voltage output to fluid level. Both sensors operate on a 5 Vd.c. power supply, have robust design elements such as all stainless steel wetted parts, and can be customized to the application-specific need of the particular OEM requirements, Kavlico said. When used in combination, the two sensors measure both the level and the concentration of urea in the fluid.

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