Low level continuous monitoring of NO and NOx in flue gases is essential for controlling SCR (and SNCR) deNOx systems. EES Delta Measurement's NO and NOx Monitoring Systems incorporate a custom designed extractive probe and chemiluminescent analyzer providing precise SCR/SNCR measurement of inlet and outlet NOx allowing efficient control. The robust systems provide years of maintenance-free operation even in high ash and high sulfur environments. EES Delta Measurement's products are ideally suited for challenging monitoring and control applications.