ECM’s NH3 5250 is a versatile and rugged NH3 analyzer for the development of diesel and lean-burn engine (i.e. λ > 1) SCR (selective catalytic reduction) systems. NH3 is measured using a ceramic sensor that is mounted in the exhaust of the engine. Ease-of-use, speed, compactness, and robustness are hallmarks of this technology. No sample lines or pumps are required, simplifying installation and giving fast response. Distances of up to 100 meters between the sensor and analyzer are possible with no loss in response time or accuracy. NH3 sensors have their calibration stored in a memory chip in the sensor’s connector. Calibration can be performed by the user (Zero, Span) and is written into the same memory chip. This allows sensors to be calibrated in a central location and distributed to users, ensuring consistent results throughout a large test facility.
The NH3 5250 can be used with all fuel types. All sensor parameters including sensor voltages, cell resistance, and heater voltage are available for display and output. A second NH3 channel can be added and displayed/output.
The NH3 5250 is remarkably compact and is suited for both dynamometer and in-vehicle applications. With six analog outputs and CAN communication, the NH3 5250 can be integrated into any data acquisition system. To simplify in-vehicle use, the NH3 5250 can be turned on and off with a signal from the vehicle’s ignition switch. This feature along with the analyzer’s CAN communication capability makes it possible to use the NH3 5250 in the loop of a real-time emissions control strategy.
The control of urea injection in SCR systems is difficult. Not enough urea and NOx emissions rise. Too much urea and NH3 emissions and urea use rise. Urea injection control during transient operation is especially difficult and requires fast NH3 instrumentation. The NH3 5250 makes this difficult measurement with ease and is a necessary tool for the development of modern SCR systems.
