SOx, NOx, and CO monitoring

About SOx, NOx, and CO monitoring

Measurement Ranges

• SOx (SO): Typical measurement ranges are from 0200 ppm to 05,000 ppm, depending on regulatory requirements and process conditions.
• NOx (NO, NO): Measurement ranges often vary from 0100 ppm to 01,000 ppm, adjustable based on the expected concentration in the exhaust.
• CO: CO is often measured in percentage values, typically 020%, although some applications may require lower or higher ranges (e.g., 050%).

Detection Methods

• SOx: Commonly measured using UV fluorescence, non-dispersive infrared (NDIR), or electrochemical sensors.
• NOx: NOx levels are measured using chemiluminescence, NDIR, or electrochemical detection.
• CO: Primarily monitored using NDIR sensors or infrared gas analyzers.

Response Time

• SOx and NOx: Generally, response times range from 30 seconds to 2 minutes for real-time monitoring.
• CO: Typically has response times around 15 to 30 seconds.

Accuracy and Precision

• SOx: Typically 1% of full scale.
• NOx: Around 2% of full scale.
• CO: 1% of the measurement range.

 Resolution

• SOx: Typically around 1 ppm.
• NOx: 0.11 ppm, depending on sensor sensitivity.
• CO: Typically 0.01% for higher precision.

 Operating Temperature

• Generally from -20C to +50C for standard stack monitoring systems, but some applications may require operation in higher temperature ranges (up to 300C with cooling or sample conditioning).

 Sample Conditioning System

• Includes filters, condensers, and pumps to prepare samples at high temperatures and humidity, especially in combustion environments.

Data Output and Communication

• Output Signals: 420 mA, RS-485, Modbus, Ethernet for integration with SCADA or other data acquisition systems.
• Data Logging: Systems should have onboard memory and support for data logging, as well as remote data access options.

Compliance Standards

• Should meet standards such as U.S. EPA 40 CFR Part 60, European EN 14181, and local environmental regulations for emissions.

Calibration Requirements

• Automated or manual calibration with span and zero gases (e.g., nitrogen for zeroing, standard reference gases for span calibration). Calibration intervals depend on regulation and analyzer type.

These specifications ensure that SOx, NOx, and CO monitoring systems meet the accuracy, reliability, and regulatory compliance required for effective emissions monitoring in industrial applications