Model 951C Chemiluminescence NOx Analyzer (19"Rack Mount)

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Chemiluminescence detection technique Measures NOx in stationary source monitoring applications 0.1 ppm sensitivity; delivers accurate measurements over a wide selection of full-scale ranges Standard 19" Rack Mounting 4 Field Selectable Ranges Thermoelectrically-Cooled Detector and Temperature Controlled Case Atmospheric Pressure Operation Internal UV Ozone Generation Internal Sample Bypass Flow Automatic Air Switch Prevents Ozone Damage 4 1/2-Digit LCD Display in ppm NOx Meets or Exceeds CEMS Application Needs

FEATURES AND APPLICATIONS Simplified operation and ease of maintenance are the key design features of Rosemount Analytical's Model 951C NOx Analyzer. Designed for source emissions analysis in Continuous Emission Monitoring Systems (CEMS), the Model 951C delivers top performance and reliability. With the thermoelectrically-cooled photomultiplier tube and temperature-controlled case, the Model 951C offers superior low range performance. Featuring precision of 0.5%, the Model 951C NOx Analyzer delivers accurate measurement over a wide selection of fullscale ranges. Simplified operation and maintenance of the Model 951C are assured by the convenience of front pull out access to all serviceable parts and operating controls. A 4 1/2-digit, backlighted LCD display ensures high visibility of concentration reading at all leverls of ambient light. Designed for single range operation, the Model 951C front panel includes recessed zero and span controls, leaving a clean, modern instrument look. The Model 951C NOx Analyzer features a heated, temperature-controlled, carbon-based converter for NOx analysis. This unique converter, operating at a relatively low temperature, offers prolonged life and freedom from interference that may adversely affect other types of converters. Control of the converter tmperature and a heater indicator lamp are provided behind the front panel for simple adjustment. Since the analyzer's reaction chamber operates at atmospheric pressure, problems normally associated with auxiliary vacuum pumps are eliminated. To minimize system response time, an internal samplebypass feature provides high-velocity sample flow through the analyzer. The Model 951C internally generates reactant ozone by exposing air to ultraviolet (UV) radiation from a source lamp. The use of UV radiation to produce ozone eliminates the generation of spurious NO normally found in corona discharge type generators. To ensure safety during normal operation, the ozone generator operates at a temperature far below the ignition point of surrounding materials. A pressure activated switch quickly shuts off the ozone generator when reactant air or oxygen is removed thereby preventing lamp and analyzer damage from ozone buildup. Low installation and maintenance costs are designed into the analyzer. The 19" rack mountable, unitized enclosure has all electrical and signal connections conveniently located behind a rear access panel. The Model 951C offers four selectable fullscale ranges of 10, 25, 100, 250 ppm NOx with electronic zero and span controls for simple calibration adjustment. A high range option is available including 100, 250, 1000 and 2500 ppm NOx. Continuous recorder outputs of 0 to 5 VDC and 0/4 to 20 mA are available at rear panel terminals. PRINCIPLE OF OPERATION The chemiluminescence detection technique is based on the principle that nitric oxide (NO) reacts with ozone (O3) to produce nitrogen dioxide (NO2), 10 % electronically excited nitrogen dioxide (NO2*) and oxygen. Following the NO-O3 reaction, the NO2 molecules immediately revert to NO2. This process creates a light emission directly proportional to the NO concentration in the sample. The intensity of the resulting light emission is then measured by a photomultiplier tube and associated electronics. An NO2 to NO converter is used for NOx (NO + NO2) analysis.