Cerex Monitoring Solutions, LLC.

- Model FTIR - Open Path Multi-Gas Analyzer



The Cerex AirSentry FTIR multi-gas analyzer is the recognized choice in open path FTIR and the most reliable for monitoring industrial facilities, accidental releases, and hazardous waste site emissions. The system monitors from 5 to 1,000 meters and eliminates the need for many single point gas specific sensors, lengthy calibrations, and laboratory analysis. The Cerex AirSentry FTIR is the only commercial open-path FTIR evaluated in two USEPA site studies and proven capable of detecting, identifying, and quantifying air toxics. It is efficient as an alarm and easily integrated into your existing alarm system.


The Cerex AirSentry FTIR is the only commercial open-path FTIR evaluated in two USEPA SITE studies and proven capable of detecting, identifying, and quantifying air toxins. It is efficient as an alarm and easily integrated into your existing alarm system.

  • USEPA TO-16 Regulatory Compliant Monitoring: 385 Compounds, 100+ HAPs
  • Direct SAFER Systems Integration
  • MODBUS TCP Integration
  • VNC Remote Control
  • Part per Billion Sensitivity
  • Automated Reporting
  • Automated Alarms
  • Simple .csv or .txt Data Logging
  • Easily configured for your application
  • Tripod mount or fixed installation
  • Optional Hazardous Location Hardware

Multi-Compound Detection Capabilities

Offering real time quantification of multiple compounds, the Cerex AirSentry FTIR provides a cost effective multi-component perimeter fugitive emissions or LDAR monitoring solution. Monitoring as few as two gases with the AirSentry FTIR often results in lower initial and lower ongoing operational costs than utilization of competing gas detection technologies, while simultaneously delivering reliable U.S.E.P.A. TO-16 regulatory compliant air quality monitoring. The AirSentry FTIR is offered fully configured to meet the requirements of your air quality monitoring application. Target gases are selected from Cerex’s library of 385 compounds. Changing target gases is as simple as copy and paste.

Enhanced Early Detection Performance

Low PPB detection limits and wide dynamic ranges enhance early leak detection and release characterization in real time. Concentrations of gases below the detection thresholds of traditional sensor arrays are detectable with the AirSentry FTIR. Early detection translates into quicker response times, reduced impact and decreased plant downtime. Clear down is immediate, and the analyzer cannot be poisoned.

Low Maintenance Costs, Increased Uptime

The AirSentry FTIR is designed for autonomous operation and a twenty year service life. Units produced in 1994 are still operational today. The analyzer uses a cryocooled MCT detector which mitigates the require-ment for costly liquid nitrogen handling and ensures continuous operation. Only two consumable items: The IR source and the MCT detector cryocooler compressor. Both consumables have three year service intervals. Air conditioning increases longevity of electronics. Optical surfaces are coated to reduce corrosion. Inherent calibration eliminates the need for time consuming and expensive routine calibration. Quality assurance au-dits require only small quantities of primary standard gas.

Low Cost Installation and Integration

For many installations complete perimeter monitoring may be achieved with only two power and communi-cation installation locations. MODBUS TCP and VNC via Ethernet are standard communication and remote control protocols.

Direct Integration with SAFER Systems Modeling

The AirSentry FTIR seamlessly integrates with SAFER Systems’ emergency response software. SAFER’s patent-ed software is used in conjunction with Cerex hardware in several different ways; pre-emergency for prepara-tion and training, during an emergency for emergency response, and post-emergency for future event mitiga-tion, regulatory reporting, and litigation response. The complete solution utilizes live streaming data from on-site weather stations and Cerex gas detection sensors to generate a visualized model of the chemical plumes or soot clouds released during an emergency. The models automatically update as weather/sensor data changes so that emergency response teams know who or what will be impacted by the emergency (whether on-site or off-site), who needs to be evacuated or shelter in place, and how long the event will last. In the case of highly flammable chemicals, the models show where the combustion particulates will be deposited as well as the chemical composition of the soot clouds. All of the models and data are archived so they can be used for post-emergency analysis of the event, in response to odor complaints and litigation, and for re-porting to regulatory agencies when needed. Not only can response teams use pre-defined scenarios prior to an emergency, but they can also use the archived data and models to base their emergency drills and training on actual events that may have occurred.

Flexibility for Open Path and Point Monitoring

For monitoring projects which require the flexibility for open path and point monitoring, the AirSentry FTIR may be quickly converted from an open path analyzer to a point analyzer by replacing the telescope with an optional multi-pass sample cell.

Core Data Acquisition and Integrated Meteorological Monitoring

With optional inputs the AirSentry FTIR may be configured to acquire and integrate data from ancillary ana-lyzers and meteorological monitoring hardware to offer definitive records of site conditions.

Open Path FTIR Principle of Operation

The Cerex AirSentry FTIR operates by sending a beam of Infrared light through the open air. The IR beam is reflected back to the analyzer by a retro-reflector array (mono-static), where the absorption due to target gases is measured and recorded. The analyzer uses a classical least squares regression analysis to compare the measured absorption spectrum to calibrated reference absorption spectra files per USEPA TO-16 Methodology. Beer’s Law is used to report accurate gas concentrations.

Mono-static Design and Installation

The AirSentry FTIR mounts to a precision pan and tilt head which may be used with a tripod for rapid deployment, or with a fixed mount for permanent installations. The retro-reflector array is housed in a NEMA enclosure and may be tripod or fixed mounted to a mast, pole or superstructure. Monitoring path lengths are typically configured to meet minimum detection limits required for the project. Paths to 1 Km are possible. The IR beam is eye-safe and the analyzer may be located directly in the breathing zone. Gases present in the beam path are identified and quantified in near real time.

Software and hardware features are specifically designed to simplify integration , automate operation and reduce maintenance. Tedious calibrations are unnecessary and the use of synthetic background functionality allows continuous and accurate quantification of gases that are always present without the need for complex background acquisition procedures.

  • Integrated Computer with Windows
  • Cryocooled MCT detector eliminates need for Liquid Nitrogen
  • Integrated WiFi , LAN, USB
  • User configurable alarms and data acquisition rate
  • MOBUS TCP and Ethernet VNC Networking
  • User configurable resolution
  • Inherent calibration: No need for ongoing calibrations
  • Simultaneous multi-gas detection capabilities
  • Automated background acquisition
  • Part per billion minimum detection limits (gas specific)
  • Automated synthetic background implementation
  • Integrated instrument air conditioning

AirSenty FTIR Options

  • Integrated Meteorological Monitoring
  • Internal Flow Through QA Cell
  • Analog inputs, integrated data logging
  • External Multi-pass Cell
  • Collocated Particulate Monitoring
  • Extended Temperature Range
  • Serial Modbus, 4-20mA, 0-5VDC
  • Alarm driven control outputs
  • RS-232, 422, 485 output
  • HAZLOC Z-Purge, Air Conditioning
  • USB Cellular Modem or RF Modem
  • Automated Multi-path Scanner

Cellular Modem provides remote access to user interface, data and alarms

Analyzer: AirSentry FTIR

  • Application: Open Path Mono-static Multi-Gas FTIR Analyzer


  • Analyzer Dimensions: 23.27” X 42.11” X 21.93”
  • Mounting: Pan and Tilt Head via Dovetail for Tripod or Fixed Mount
  • Power: 120 or 240VAC, Single Phase 50-60Hz , 4A Max
  • Networking: Sealed LAN, WAN and USB Ports, optional cellu-lar modem, optional radio modem
  • Operating Temperature: ºC to +55ºC
  • Operating Humidity: 0-80% NC
  • Sample Path Length: 5-1000 Meters Open Path
  • Detector: Cryocooled MCT Photodetector


  • Spectral Resolution: User Selectable: 1,4, 8, 16 , 32, 64 wavenumber
  • Spectral Range: 2—14 Micron
  • Dynamic Range: Application Specific
  • Background Drift (TYP): < 2% FS / 24hr, Self-Compensating
  • Linearity Drift (TYP): < 2%, Self-Compensating
  • Accuracy: Application Specific: TYP
  • Calibration: Inherent, optional QA cells available
  • Regulatory Approvals: USEPA Method TO-16 Compliant
  • Data Output: .CSV or .TXT via Ethernet and WiFi, MODBUS
  • Data Output Options: 4-20mA, 0-5VDC, RS-232, 422, 485, RF Stream, MODBUS RTU, Email
  • Alarms: User configurable concentration and TLV aver-aged concentration alarm functionality


  • IR Source Life: 3 Years
  • Cryocooler MTTF: 20,000 Hours

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