Open Path Detection of Hazardous Gases

Open Path Detection of Hazardous Gases

Avir Sensors Proprietary

Open path, non-contact chemical detectionMultiple chemicals detected and identified by a single detectorRapid detection and identification (

ChemSight Architecture*Avir Sensors Proprietary*Based on infrared spectrometry operating in the 830-1250 cm-1 (fingerprint region) 2000-3300 cm-1 spectral ranges


Open Path, Non-contact Chemical DetectionLarge coverage areaNo contact required for detection and identification and, consequently, no sensor poisoningStand off detector does not require predicting potential release areasApplicable to inaccessible locationsDesignated a Department of Homeland Security SAFETY Act Qualified Anti-terrorism Technology (QATT)*Avir Sensors Proprietary*


Patented ChemVECTOR algorithm recognizes and identifies chemicals infrared signatures in one second Detection and identification confirmed over user-defined intervals (30 seconds typical)Large on-board database of chemical signaturesUser configurable alert and alarm actionsEasily operated by untrained personnel

*Avir Sensors Proprietary*Instant Alert and Identification


Selected Hazardous Gases*Avir Sensors Proprietary*


Patented ChemVECTOR detection and identification algorithm allows:Chemical detection and identification well below IDLHDetection of high and low chemical concentrationsRejection of background interferants while maintaining trace level sensitivityFull system verification using on-board confidence testerSealed to IP66 standards for continuous operation in harsh environmentsLess than 20 watts power consumption*Avir Sensors Proprietary*Sensitive, Specific, Reliable, and Robust


*Avir Sensors Proprietary*Path Integrated Concentrations


Representative Sensitivities (Over 100 meter path)*Avir Sensors Proprietary*1 Second30 SecondsAll units in ppm

ChemicalIDLH DetectIdentifyDetectIdentifyAmmonia3000.81.00.30.3Ethylene Oxide8000.52.00.20.5Hydrogen Chloride504.64.84.44.5Hydrogen Cyanide504.35.02.32.8Phosgene20.170.250.120.2Vinyl Chloride4501.012

Receiver Operating Characteristic (ROC) CurvesROC curves describe the likelihood of correct dichotomous decisionsa patient has a disease / does not have a diseasean anomaly has been detected / has not been detecteda chemical is present / not present*Avir Sensors Proprietary*


Illustrative ROC Curves*Avir Sensors Proprietary*0.5

True Positive rate

CT brain lesions: AUC 97%mammography: AUC 78-91%diabetes: AUC 81%polygraph: AUC 55-75%Polygraph(police)DiabetesscreeningMammographyscreening

CT brainlesions

0.51.01.00False Positive rate


*Avir Sensors Proprietary*75 ppmm ammonia, 1 sec average ChemSight ROC Curves


*Avir Sensors Proprietary*75 ppmm ammonia, 30 sec average ChemSight ROC Curves


Low Maintenance, Low Ownership CostNo consumables No ongoing calibration requiredDetector is monitored for blockage, dirt accumulation and other fault diagnosisInterfaces with standard security software systemsNew chemical signatures added to database via softwareOn-board, full system confidence tester activated at user defined intervals*Avir Sensors Proprietary*


Perimeter protectionHVAC systemsRailway platformsPortsAirports

StadiumsChemical manufacturing and storage facilitiesManufacturing facilitiesEnvironmental monitoringSchools*Avir Sensors Proprietary*Typical Applications


*Avir Sensors Proprietary*Return on Investment

BenefitsReturn on InvestmentLarge area coverageLow cost per area coveredOne detector indentifies multiple chemicalsLow cost per chemical sensed Few sensors requiredNo scheduled maintenanceLow ownership cost On-board, full system confidence tester Untrained OperatorsIntegration with existing control systemsLow integration costs No specialized software requiredSoftware updatableAdd latest chemical threats Modify alert levels or alarms remotelyLong-term data storageForensics Monitor against long-term threats (ramp-up)


Designated a Department of Homeland Security SAFETY Act Qualified Anti-terrorism Technology (QATT)Metro RailIndustrial InstallationsCarbonated beverage manufacturingDefense Logistics AgencyInstitutional Ventilation*Avir Sensors Proprietary*Technology Heritage

Reference SupportersArmy/Edgewood ResearchOffice of Naval ResearchPrivate EntitiesTechnical Support Working Group (TSWG) and DHS/DOSUniversity of VirginiaVirginia Center for Innovative Technology


Mahalanobis Distance Technique*Avir Sensors Proprietary*


The Mahalanobis Distance is a mathematical tool that is part of ChemVECTOR, a patented detection and identification algorithm unique to the ChemSight.When a hazardous gas or interferant crosses the IR beam, ChemVECTOR determines:the mathematical magnitude relative to ambient air for detectionthe mathematical proximity to signatures in the chemical database for identification*Avir Sensors Proprietary*Prasanta Chandra MahalanobisMahalanobis Distance


*Avir Sensors Proprietary*Ammonia at 70F/30% RH, 30 sec averagingMahalanobis Distance Plot


The MD-based mathematics in ChemVECTOR allow reliable detection and identification when over a wide range of concentrations even in the presence of a heavy load of interferants.Unlike alternative algorithms (e.g., principal component analysis - PCA), ChemVECTOR allows chemical signatures to be added to the signature database in any combination without recalculating the entire database.Detection and identification thresholds can be adjusted by ChemVECTOR. *Avir Sensors Proprietary*Uniqueness of ChemVECTOR


Physical and Software Schematics*Avir Sensors Proprietary*


ChemSight Detection and IdentificationDetectionDetection occurs when a new signal significantly exceeds background noise level.A mathematical threshold is set to create an acceptable level of false alarms. This threshold defines sensitivity.

IdentificationIdentification occurs when a new signal matches a signature in the library.For positive identification, the match needs to be within a mathematically determined threshold by ChemVECTOR.When positive detection occurs but the signal is outside the identification threshold the ChemVECTOR issues an Unknown message.*Avir Sensors Proprietary*


*Avir Sensors Proprietary*Internal Layout of ChemSight3) Band pass filters parse spectrum and send signals for processing2) Rotating Mirror concentrates light on detector array1) IR Light Enters DetectorChemSight Optical Layout


7.0*Avir Sensors Proprietary*7.522.5ChemSight Detector Dimensions


ChemSight Source Dimensions*Avir Sensors Proprietary*14148


SiteProtector Software Layout*Avir Sensors Proprietary*


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Open Path Detection of Hazardous Gases