How do Gas Analyzers work?
Ambient gas analyzers use a selective physical or chemical reaction to convert a gas concentration into an electrical signal. Sulfur dioxide is measured by ultraviolet fluorescence, where SO2 molecules excited at 214 nm emit light whose intensity is proportional to concentration. Nitrogen oxides are determined by chemiluminescence, reacting nitric oxide with ozone to produce light, with a molybdenum converter reducing NO2 to NO for the total. Carbon monoxide is measured by non-dispersive infrared absorption, often with gas filter correlation to reject interference. Ozone is determined by ultraviolet absorption at 254 nm in a dual-cell or single-cell design that alternates sample and scrubbed air. Sample conditioning removes particles and moisture, and internal computers apply zero and span corrections for temperature and pressure.
Which Gas Analyzers variants are available?
- UV Fluorescence SO2 Analyzer — A reference-grade analyzer that measures sulfur dioxide in ambient air by ultraviolet fluorescence.
- Chemiluminescence NOx Analyzer — A reference-grade analyzer that measures nitric oxide, nitrogen dioxide and total nitrogen oxides in ambient air by chemiluminescence.
- NDIR Carbon Monoxide Analyzer — A reference-grade analyzer that measures carbon monoxide in ambient air by non-dispersive infrared absorption.
- UV Photometric Ozone Analyzer — A reference-grade analyzer that measures ozone in ambient air by absorption of 254 nm ultraviolet light.
- Electrochemical Multi-Gas Air Quality Analyzer — A compact analyzer with interchangeable electrochemical sensors that measures several gases such as SO2, NO2, O3, CO and H2S at once.
How do I choose the right variant?
Choose the analyzer by the gas, the required measurement range and whether the data must satisfy a regulatory method. Reference-grade instruments follow EN or US EPA methods and provide the stability, detection limit and averaging time that monitoring networks require. Range should bracket the local concentrations and include the limit value, for example 0–500 ppb for SO2 and NOx in urban air or 0–50 ppm for CO near traffic. Consider interference rejection, response time, zero and span drift specifications and the calibration gas requirements. For indoor or occupational checks, portable or electrochemical analyzers with lower ranges and simpler calibration often suffice. Confirm output protocols, data logging and the availability of a multipoint calibration system.
Where are Gas Analyzers used?
Gas Analyzers are specified in urban air quality monitoring networks, industrial fence-line and plant perimeter monitoring, roadside and traffic-related pollution studies and indoor air quality and occupational checks.
Which standards and certifications apply?
Work with Gas Analyzers is commonly governed by EN 14212 (SO2), EN 14211 (NOx), EN 14626 (CO), ISO 13964 (ozone), US EPA 40 CFR Part 50 Appendix A and HJ 654. Instrument certifications such as CE marking are confirmed per configuration and never assumed.
What are the key considerations before purchase?
Install analyzers in a temperature-controlled shelter or rack with clean, dry sample lines and a manifold that provides stable flow. Calibrate with certified gas standards and a dynamic dilution system, performing zero and span checks on the schedule required by the method, and keep records of converter efficiency for NOx instruments. Replace particulate filters, dryers and pump diaphragms regularly, and verify sample flow and pressure. Protect optical components from dust and condensation, and allow warm-up and stabilization before reporting data. For regulatory networks, follow quality assurance and quality control procedures such as US EPA 40 CFR Part 58 Appendix A and retain raw data for audit.
