California Analytical Instruments, Inc. (CAI)

600 Series NOxBox



The California Analytical Instruments’ NOxBox system has been specifically designed for harsh environment conditions frequently found in outdoor selective catalytic reactor applications. The analyzer system is housed in a Nema 4 enclosure with a front lockable door. The enclosure contains a heating and cooling system to maintain a constant internal temperature for the gas analyzer and interface equipment regardless of outside environmental effects. The sample is obtained directly through a heated sample line, after the optional heated filter.

The NOxBox contains the latest CAI digital heated Chemiluminescent analyzer with an optional paramagnetic oxygen analyzer and water removing sample conditioning system. Complete automatic diagnostics and alarms are standard with digital output to control systems, including TCP/IP.

Designed as a close coupled system, with sample, including pump, maintained above 100°C, the direct wet measurement technique greatly simplifies sample conditioning. The enclosure houses all the components necessary to perform continuous NO/NOx measurement of the sample. A optional zero air generator is available for pure air for the NOx analyzer’s ozone generator and zero air for calibration.


The heated NOx analyzer utilizes the principle of chemiluminescence's for analyzing the NO or NOx concentration within a gaseous sample. In the NO mode, the method is based upon the Chemiluminescent reaction between ozone and nitric oxide (NO) yielding nitrogen dioxide (NO2) and oxygen. This reaction produces light which has an intensity proportional to the mass flow rate of NO into the reaction chamber. The light is measured by means of a photodiode and associated amplification electronics. In the NOx mode, NO plus NO2 is determined as above, however, the sample is first routed through the internal NO2 to NO converter which converts the NO2 in the sample to NO. The resultant reaction is then directly proportional to the total concentration of NOx. Local operation is simplified using the 20 button alphanumeric keypad with data presented on a back lit LCD display.

The optional oxygen analyzer section utilizes the paramagnetic method to determine the percent level of oxygen contained in the sample gas. The sample gas first passes through a chiller unit to remove condensation before entering the detector.

All local operations may be performed remote via RS-232 and/or TCP/IP which can be transferred to the SCR controller.


  • SCR Monitoring
  • Stack Gases (CEM)
  • Scrubber Efficiency
  • Combustion Efficiency
  • Turbine/Generator Feedback Control
  • Process Chemical Gas Analysis
  • Power Plant De-Nitrification
  • Fuel Cell Analysis
  • Vehicle Emissions


  • Paramagnetic Oxygen Analyzer With Sample Conditioning System
  • Internal ZAG-XL Zero Air Generator
  • Heated Sample Line/Remote Heated Filter
  • Externally Mounted Drier for Customer Compressed Air Supply
  • Provision for Monitoring Multiple Points
  • Alarm Relays


  • Model 600 HCLD Contained in Temperature Controlled NEMA 4 Enclosure
  • Four User-Definable Ranges From 0-3 to 0-3,000 ppm
  • Auto Calibration and Ranging
  • Fast Response Time
  • Electronic Sample and Ozone Flow Control
  • Comprehensive Diagnostics
  • Output Options: Voltage, Current, RS-232, TCP/IP
  • Remote Monitoring and Control
  • Data Archiving

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