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Cerex Indoor Air Quality (IAQ) FTIR

Point analyzer for high sensitivity gas sampling

The Cerex Indoor Air Quality (IAQ) FTIR keeps your environment safe from toxic ambient substances. It achieves this through acute sampling, reliable FTIR technology, and swift data acquisition.

  • Over 350 compounds available for analyzing
  • Deep sensitivity – down to parts-per-billion detection limits
  • No lengthy calibrations or time-consuming laboratory analysis
  • View real-time results on a laptop, PC or mobile device from anywhere in the world via remote connection
  • Make informed decisions quickly with automatic alerts sent directly to your device

IAQ FTIR (Standard)

Weight 65lbs
Measurements 24″ x 20″ x 12″ (60.96cm x 50.80cm x 30.48cm)
Enclosure Stainless Steel

AC Power 4A at 100V/120V
Operating Temperature -20°F to 104°F (-29°C – 40°C)


  • Wall mounted with brackets; inlet and outlet ports for tube connections


  • Recommend semi-annual inspections of dirt buildup on the exterior heat-sink fins.
  • Rinse air conditioner fins as needed

How it Works

Point FTIR Technology

Point Technology

The IAQ FTIR operates using a process known as point monitoring. Surrounding ambient gases are channeled into the analyzer via sample tubes to an inlet port. Following this, an internal cell holds the gas sample for analysis.

FTIR Technology

Next, with FTIR technology, an infrared light passes through the gas sample contained within the cell. Thanks to a physics principle known as the Beer-Lambert Law, an ultra sensitive spectrometer, and Cerex’s proprietary software (CMS), the concentrations of the specific gases within the sample is translated into real-time data.

Common Detectable Gases

Extensive Library with Options for Customization

Cerex has over 350 compounds available for detection with the IAQ FTIR. If your compound is not one of the compounds already available within our database, the Cerex IAQ FTIR may import gas spectra from the numerous FTIR databases on the web (NIST, EPA, PNNL, etc.)

If you have a compound that is not available in a public database, we may be able to work with you to develop a custom spectrum. Detection limits are a function of the IR detector, installed path length, and site conditions. The detection limits shown have been empirically determined from bump tests of fielded instruments at full path-length.

It is efficient as an alarm and easily integrated into your existing alarm system.

*NOTE: If desired target gases are available within the UV spectrum, we recommend Cerex UV Products for better pricing options. If you’re not sure, we can help you find the right analyzer for your application.

IAQ FTIR Common Target Gases

Acetaldehyde (C2H4O)
Acetic Acid (C2H4O2)
Acetone (CH3COCH3)
Acetylene (C2H2)
Acrolein (C3H4O)
Benzaldehyde (C7H6O)
Butane (C4H10)
n-Butyl (C6H12O2)
Carbon Dioxide (CO2)
Carbon Monoxide (CO)
Chlorine Dioxide (ClO2)
Ethane (C2H6)
Ethanol (C2H6O)
Formaldehyde (CH2O)
Formic Acid (CH2O2)
n-Hexane (C6H14)
Hydrogen Bromide (HBr)
Hydrogen Chloride (HCl)
Hydrogen Fluoride (HF)
Methane (CH4)
Nitric Oxide (NO)
Nitrogen Dioxide (N2O)
Phenol (C6H5OH)
Phosgene (CCl2O)
Water Vapor (H2O)


Results You Can Rely On

Cerex recognizes that detailed gas monitoring results need to be reliable and available quickly to various stakeholders. For this reason, Cerex engineers developed software to accurately detect and display gases within the air in real time from any location.

On an IAQ FTIR, a user can see results remotely on a phone, tablet, or computer anywhere in the world via a virtual connection.

All data is automatically saved in an easy to access .csv file, and archived daily for future referencing. This feature helps our clients in various ways - from daily use to crucial events such as evidence in court. Early detection translates into quicker response times, reduced environmental impact, decreased plant downtime, and reduced exposure of harmful chemicals to site personnel and community.

Learn more about the benefits of our proprietary analysis software here.


Real time spectral subtraction and synthetic background implementation allow the Air Sentry to clearly display accurate concentrations of target gases over 1000 meters without interference from other gas species


From ambient to process

For many applications, you don't need exorbitant equipment or costly, extractive laboratory analysis to get accurate results. With it's condensed, all-in-one design and ability to detect hundreds of detectable compounds, the IAQ FTIR is a highly cost-effective, low-maintenance system that suits a variety of applications.

All Applications

Ambient Air Monitoring

Anesthetic / Hospital Monitoring

Chemical Manufacturing AQ

Chemical Warfare Agent Detection

Container Inspection

General Industrial Air Monitoring


Indoor Air Monitoring

Leak Detection

Manufacturing Air Quality

Odor Complaint Response

Refinery Air Quality Fertilizer

Response Border Patrol Inspection

Stationary Source Monitoring
(Cool, dry sample)

IAQ FTIR Specifications

General Parameters
Part Number Shepherd FTIR
Analyzer Type Multi-gas portable point analyzer
Technology Fourier Transform InfraRed (FTIR) Differential Optical Absorption Spectroscopy (DOAS)
Performance Available with standard HAP (385 compound & 62 Compound), Criteria, Hospital and custom gas detection libraries.
Data Output Rate User selectable from 5 seconds and up
Typical output rates are 30s, 60s, 120s, or 300s
Time weighted average available for user defined periods (8 hour, 12 hour, 24 hour)
Measurement Principle Beer-Lambert Law
Measurement Technique Classical Least Squares (CLS) regression analysis; optional Partial Least Squares (PLS)
Operating Temperature 0°C to 35°C (Optional Air Cooled Model)


Storage Temperature -40C° to 60C°
Power Supply 100 to 130V or 200 to 240VAC/50-60Hz
Power Consumption 240W MAX
Instrument Cooling Air Cooled
Installation Fixed mount or tripod mount (open path analyzer mode)
Bench-top (point analyzer mode)
Dimensions 42.1" x 21.9" x 23.3" (107cm x 55.7cm x 59.1cm)
Weight 85 lbs (38.6Kg)
Measuring Parameters
Concentration measurement accuracy ±5 % Reading TYP
Concentration measurement precision ±5 % Reading TYP
Interferent Mitigation Real time spectral subtraction and residual subtraction, multi-peak analysis.
Zero point calibration Simultaneous dual mode natural zero and/or synthetic zero on gas by gas basis. Automated compound specific background selection.
Real Time Operating Software Cerex Continuous Monitoring Software (CMS)
Operating System Windows 10 Pro
Post Collection Analysis Software Cerex Data Processor
Operating System Windows 7, 8, 10
Apodized Resolution User selectable: 0.5 cm-1, 1 cm-1, 2 cm-1, 4 cm-1, 8 cm-1, 16 cm-1, 32 cm-1
Scan frequency 6 scans/s @ 32 cm-1
Detector Stirling Cooled MCT (standard)
TE Cooled MCT (application dependent)
Detector temperature 77 K (Stirling cooled MCT)
Source SiC, 1550K
Beamsplitter ZnSe (standard)
Window material ZnSe (standard)
Wavenumber range 600-4200 cm-1 
Temperature stability < 1% per C⁰
Frequency repeatability  < 0.001 cm-1 @ 1918cm-1
Frequency accuracy < 0.06 cm-1 @ 1918cm-1
Short term stability < 0.09%
Maximum signal to noise ratio 50,000: 1 (RMS, 60s, 4 cm-1, at peak response)
Signal sampling 24-bit ADC
Quality Assurance Hardware
Type Internal linear multi-pass cell permanently mounted in beam path. External window removable.
Calibration gas inlet Quick Connect QA Adapter: 1/4" Swagelok
Calibration gas outlet Screw-in Exhaust Adapter: 3/8" Swagelok
Path Length 19.2 m
Volume 3.4 L
Maximum sample pressure 1 PSI
Pressure and temperature measurement Integrated pressure and temperature sensor
HMI Touchscreen (standard model)
Digital Interface RJ45 Ethernet LAN Port for local or internet based remote data and access using MODBUS TCP, VNC, and remote desktop.  Spectral data may be stored locally, on a NAS, or disabled. Industrial external wireless option available. Type A USB for data retrieval and peripheral accessories.
Power Connection Environmentally sealed circular Amphenol bayonet connector.
Integrated Computer Embedded industrial PC
Integrated Wind Mapping Three dimesnional ultrasonic anemometer with temperature measurement. Data integrated into CMS data tables and available via MODBUS.
Integrated Data Acqusition External ports with data integration for particulate or ancillary co-located analyzers (TDLAS laser, electrochemical, etc.).
Data Output MODBUS over RS-232, RS-485.  MODBUS over TCP-IP is standard.
Analog Output 8 channel configurable 0-24mA (4-20mA with extended range)


(Coming Soon) IAQ FTIR Standard Model Brochure (PDF)
(Coming Soon) Technical Sheet - Specifications (PDF)

Type Compound MDL PPB
Criteria Sulfur Dioxide 300
Volatile Organic Compounds Acrolein 15
1,3 Butadiene 4
Styrene 8
BTEX Benzene 30
Toluene 100
Ethylbenzene 25
m-Xylene 100
o-Xylene 300
p-Xylene 300
Alkanes Pentane C5 4
n-Hexane C6 3
TVOC Methane C1 3
NMHC Ethane C2 8
NMNEHC Butane C4 4
Propane C3 4
Formaldehyde 7
Propene (propylene) 6
Ethene (ethylene) 4
Acetylene 4
Acetaldehyde 5
Methanoic Acid 5
Methanol 4
Other Hydrogen Cyanide 10
Hydrogen Fluoride 4
Ammonia 3
Hydrogen Sulfide 450

Discuss your project with our application specialists

Our engineers have decades of experience in creating custom solutions to meet your monitoring challenges