Continuous Emissions
Monitors
API Model 100AH
Sulfur Dioxide Analyzer

The API Model 100AH SO2 analyzer uses the analytical technique of ultraviolet fluorescence. The instrument is microprocessor controlled and boasts sensitivity down to the 10 ppm range. Ranges are user defined from 10 to 5,000 ppm.
Manufacturer Advanced Pollution Instrumentation, (API)
Analysis Method Ultraviolet Fluorescence
Range 10 - 5,000 ppm
Zero Drift < 20 ppb / 24hrs.
Span Drift < 1% of reading /24 hrs.
Sample Flow 290 cc / min. Lag Time < 20 Seconds Switching mode < 6 Seconds NO orNOx only mode
Rise / Fall (95%) 10 Seconds NOx only Mode
Analog Output 0 - 100 mV, 1, 5 and 10V dc and 4 to 20mA
Power 115 VAC
Dimensions 7” x 17” x 23.5”
Weight 44 lbs
Bovar (Western Research) Model 721ATM
Sulfur Dioxide Analyzer

The Bovar Model 721ATM SO2 analyzer uses the analytical technique of ultraviolet fluorescence. The instrument is microprocessor controlled and boasts sensitivity down to the 50 ppm range. Ranges are user defined from 50 to 5,000 ppm.
Manufacturer Bovar (Western Research)
Analysis Method Ultraviolet Fluorescence
Range 50 to 5,000 ppm
Response Time 90% in less than 30 seconds
Sample Flow Rate 1 to 2 L/min.
Zero Drift + of 0.5 of full scale (24 hrs.)
Sensitivity + 5% of full scale
Analog Output 100 mVDC, 1 VDC, 10 VDC, 4 - 20 mA
Power 120 VAC
Dimensions 180mm x 480mm x 600mm
Weight 40lbs
Western Research Model 921 Low Level SO2 Analyzer
The Western Research Model 921 SO2 analyzer uses proprietary high-resolution ultraviolet fluorescence technology in a dual beam, dual wavelength configuration. This technology minimizes interference and quench effects that are typically found in UV based instruments. The analyzer is microprocessor controlled and incorporates a “white” sample cell for low concentration measurements.
| Ranges |
0-20 to 0-2000 ppm (user defined) |
Detection Method |
Ultraviolet Fluorescence |
Sample Gas Input |
1/4-inch Tube; 1 to 2 lpm |
Analog Outputs |
0-1, 5, 10 Vdc, 4-20mA (please specify if desired) |
Power Requirement |
110 VAC/60 Hz |
Shipping & Weight |
32x25x14 – 64 lbs |
Western Research Model 921 Standard Level SO2 Analyzer
The Western Research Model 921 SO2 analyzer uses proprietary high-resolution ultraviolet fluorescence technology in a dual beam, dual wavelength configuration. This technology minimizes interference and quench effects that are typically found in UV based instruments. The analyzer is microprocessor controlled and incorporates a standard sample cell for typical concentration measurements.
| Ranges |
0-50 to 0-5000 ppm (user defined) |
Detection Method |
Ultraviolet Fluorescence |
Sample Gas Input |
1/4-inch Tube; 1 to 2 lpm |
Analog Outputs |
0-1, 5, 10 Vdc, 4-20mA (please specify if desired) |
Power Requirement |
110 VAC/60 Hz |
Shipping & Weight |
32x25x14 – 64 lbs |
Western Research Model 921 High Level SO2 Analyzer
The Western Research Model 921 SO2 analyzer uses proprietary high-resolution ultraviolet fluorescence technology in a dual beam, dual wavelength configuration. This technology minimizes interference and quench effects that are typically found in UV based instruments. The analyzer is microprocessor controlled and incorporates a “mid level” sample cell for high concentration measurements.
| Ranges |
0-250 to 0-25,000 ppm (user defined) |
Detection Method |
Ultraviolet Fluorescence |
Sample Gas Input |
1/4-inch Tube; 1 to 2 lpm |
Analog Outputs |
0-1, 5, 10 Vdc; 4-20mA (please specify if desired) |
Power Requirement |
110 VAC/60 Hz |
Shipping & Weight |
32x25x14 – 64 lbs |
California Analytical Model ZRH SO2 Analyzer
The CAI Model ZRH SO2 analyzer is a microprocessor-controlled instrument that employs a non-dispersive infrared detector. This unit provides a backlit front panel display with “push button” controls and adjustments.
Ranges |
0-1000, 2000 ppm |
Detection Method |
NDIR |
Sample Gas Input |
1/4-inch Tube; 0.5 to 2 lpm |
Analog Outputs |
0-10 Vdc, 4-20mA |
Power Requirement |
110 VAC/60 Hz |
Shipping & Weight |
32x25x14 – 55 lbs |
Thermo Environmental Model 43H Low Level SO2 Analyzer
The Thermo Model 43H SO2 analyzer employs an ultraviolet pulsed-fluorescence detector. The pulsed fluorescence minimizes quenching and increases sensitivity at lower detection ranges. This unit includes an internal sample pump and front panel zero/span potentiometers.
| Ranges |
0-1, 2, 5, 10, 20 ppm |
Detection Method |
Ultraviolet Pulsed Fluorescence |
Sample Gas Input |
1/4-inch Tube; 1 lpm |
Analog Outputs |
0-1, 5, or 10 Vdc (please specify) |
Power Requirement |
110 VAC/60 Hz |
Shipping & Weight |
32x25x14 – 70 lbs |
Thermo Environmental Model 43H
Sulfur Dioxide Analyzer

The Thermo Model 43H SO2 analyzer is a low level analyzer which uses the analytical technique of ultraviolet pulsed fluorescence. The pulsed fluorescence increases sensitivity at lower detection ranges. This analyzer is predominantly used as part of a low level hydrogen sulfide/total reduced sulfur system. Ranging is from 1 ppm to 20 ppm.
Manufacturer Thermo Environmental Instruments
Analysis Method Pulsed fluorescence
Range 0 - 1, 2, 5, 10, 20 ppm
Linearity + 1% full scale up to 1000 ppm
Zero Drift < 0.1 ppm in 24 hrs.
Span Drift + 1% full scale in 24 hrs.
Sample Flow Rate 1 liter / min.
Analog Output 10VDC
Power 115 VAC
Dimensions 16.75” x 8.62” x 23”
Weight 45 lbs API
API Model 152
Sulfur Dioxide Analyzer

The API Model 152 SO2 analyzer uses the analytical technique of ultraviolet fluorescence. Three selectable ranges can be chosen.
Dilution - Extractive Range Instruments are available.
Manufacturer Advanced Pollution Instrumentation (API)
Analysis Method Ultraviolet Fluorescence
Range 0 - 0.5, 1, 10
Noise < 1% of reading
Zero Drift < 0.2% of reading
Span Drift < 2% full scale Sample Flow 250 cc / min.
Response Time < 60 seconds
Analog Output 0 - 5 VDC
Power 115 VAC
Dimensions 7” x 17” x 22”
Weight 56 lbs
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