Model 43i SO2 Analyzer

Measure SO2 in ambient air up to 100ppm with the Thermo Scientific™ Model 43i SO2 Analyzer, the first gas analyzer to utilize pulsed fluorescence technology to measure SO2. Reflective bandpass filters are less subject to photochemical degradation and more selective in wavelength isolation, resulting in both increased detection specificity and long-term stability.

Key Features:

  • High sensitivity and fast response time
  • Linearity through all ranges
  • Internal sample pump
  • Insensitive to changes in flow and ambient temperature

iSeries Advantage:

  • Ethernet connectivity for efficient remote access
  • Enhanced user interface with one-button programming and large display screen
  • Flash memory for increased data storage and user-downloadable software
  • Enhanced electronics design optimizes product commonality
  • Improved layout for easier accessibility to components

The Model 43i SO2 Analyzer is also available with an oxygen sensor module.

The Model 43i with Oxygen uses paramagnetic sensor technology to extend the possibilities of SOmeasurement, reading, and reporting the concentration of oxygen in the sample stream up to 100%. Additionally, programming allows the user to correct the SO2 reading for the amount of oxygen in the sample.



Detectable AnalytesSulfur Dioxide
Flow Rate0.5 L/min. (standard), 1 L/min. (optional)
Inputs16 Digital Inputs (Standard), 8 0 to 10 VDC Analog Inputs (Optional)
Linearity±1% full scale
Response Time<20 sec. (lag time) (60 sec. or less average time), <100 sec. (rise time), <100 sec. (fall time)
Span Drift±0.5% full scale
Temperature (English) Operating68°F to 86°F (Performance) or 32°F to 113°F (Operating)
Temperature (Metric) Operating20°C to 30°C (Performance) or 0°C to 45°C (Operating)
Zero Noise1.0 ppb RMS (10 sec. averaging time), 0.5 ppb RMS (60 sec. averaging time),0.25 ppb RMS (300 sec. averaging time)
Certifications/ComplianceETL, CSA, UL, CE; U.S. EPA, European (TUV), MCERTS, EQSA-0486-060, UKCA
Depth (English)23 in.
Depth (Metric)584 mm
Description43i Sulfur Dioxide Analyzer
Detection Limit< 0.5 ppb
Height (English)8.62 in.
Height (Metric)219 mm
Interferences< lower detectable limit except for the following: (EPA Levels) NO < 3 ppb, M-Xylene < 1 ppb, H2O < 3% of reading
Measurement RangePreset: 0 to 10, 20, 50, 100, 200, 500 and 1000 ppm; 0 to 20, 50, 100, 200, 500, 1000 and 2000 mg/m3; Custom: 0 to 0.05 to 100 ppm, 0 to 0.2 to 250 mg/m3; Extended: 0-0.05, 1, 2, 5, 10, 20, 50 and 100 ppm, 0-2, 5, 10, 20, 50, 100, 200, and 250 mg/m3
Mounting OptionsBench (standard), EIA, Retrofit
OutputsSelectable voltage, RS232/RS485, TCP/IP, 10 status relays,  and power fail Indication (standard). 0-20 or 4-20 mA isolated current output (optional)
Voltage100/115/220/240 V
Weight (English)48 lb.
Weight (Metric)21.8 kg
Width (English)16.75 in.
Width (Metric)425 mm
Zero Drift<1ppm/day
Unit SizeEach