Open Path Open Path Detection of Detection of Hazardous Hazardous Gases Gases
Dec 16, 2015
Open PathOpen PathDetection of Detection of
Hazardous Hazardous GasesGases
Open path, non-contact chemical detection
Multiple chemicals detected and identified by a single detector
Rapid detection and identification (<1 sec)
Sensitive, specific, reliable and robust
Low maintenance and low cost of ownership
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Technology Overview
ChemSight™ Architecture
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Based on infrared spectrometry operating in the 830-1250 cm-1 (fingerprint region) 2000-3300 cm-1 spectral ranges
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IR spectrum absorption curve is parsed into 16 segments
Each of the 16 segments is “zeroed out” to create a “background”
Chemicals passing through the line of sight absorb known frequencies of IR. The ChemSight accurately detects and identifies the signature across a wide range of concentrations.
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Open Path, Non-contact Chemical Detection
Large coverage area
No contact required for detection and identification and, consequently, no sensor poisoning
Stand off detector does not require predicting potential release areas
Applicable to inaccessible locations
Designated a Department of Homeland Security SAFETY Act Qualified Anti-terrorism Technology (QATT)
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Patented ChemVECTOR™ algorithm recognizes and identifies chemical’s infrared signatures in one second
Detection and identification confirmed over user-defined intervals (30 seconds typical)
Large on-board database of chemical signatures
User configurable alert and alarm actions
Easily operated by untrained personnel
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Instant Alert and Identification
Selected Hazardous Gases
Toxic Industrial Chemicals
Chemical Warfare Agents Industrial Materials
•Ammonia•Chloroethane•Diborane•Ethylene Oxide•Formaldehyde•Hydrogen Bromide•Hydrogen Chloride•Hydrogen Cyanide•Hydrogen Sulfide•Phosgene•Vinyl Chloride•Propylene•Carbonyl Sulfide•Acrylonitrile•And many more
•AC (Hydrogen Cyanide)•CG (Phosgene)•GA (Tabun)•GB (Sarin)•GD (Soman)•GF (Cyclo-Sarin)•L (Lewisite)•SA (Arsine)•VX
•Aqueous ammonia cleaner
•IsoClean•Stainless steel cleaner•Propane•Butane•Natural gas•Carbon Dioxide•DMMP•DIMP•Methyl Salicylate•FM-200
(Heptaflouropropane)•Sulfur Hexaflouride•Various alcohols and
solvents•Diesel and Gasoline
exhaust
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Patented ChemVECTOR™ detection and identification algorithm allows:
Chemical detection and identification well below IDLH
Detection of high and low chemical concentrations
Rejection of background interferants while maintaining trace level sensitivity
Full system verification using on-board confidence tester
Sealed to IP66 standards for continuous operation in harsh environments
Less than 20 watts power consumption
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Sensitive, Specific, Reliable, and Robust
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Path Integrated Concentrations
Representative Sensitivities(Over 100 meter path)
Chemical IDLH Detect Identify Detect Identify
Ammonia 300 0.8 1.0 0.3 0.3
Ethylene Oxide 800 0.5 2.0 0.2 0.5
Hydrogen Chloride
50 4.6 4.8 4.4 4.5
Hydrogen Cyanide
50 4.3 5.0 2.3 2.8
Phosgene 2 0.17 0.25 0.12 0.2
Vinyl Chloride 450 1.0 12 <1.0 8.0
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1 Second 30 SecondsAll units in ppm
Receiver Operating Characteristic(ROC) CurvesROC curves describe
the likelihood of correct dichotomous decisions
a patient has a disease / does not have a disease
an anomaly has been detected / has not been detected
a chemical is present / not present
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true positive rate: TP/(TP+FN) {probability of identification}false-positive rate: FP/(TN+FP) {probability of false-identification}
Illustrative ROC Curves
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0.5
Tru
e P
osit
ive
rate
CT brain lesions: AUC 97%mammography: AUC 78-91%diabetes: AUC 81%polygraph: AUC 55-75%
Polygraph(police)
Diabetesscreening
Mammographyscreening
CT brainlesions
0.5 1.0
1.0
0False Positive rate
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75 ppm·m ammonia, 1 sec average
ChemSight™ ROC Curves
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75 ppm·m ammonia, 30 sec average
ChemSight™ ROC Curves
Low Maintenance, Low Ownership Cost
No consumables
No ongoing calibration required
Detector is monitored for blockage, dirt accumulation and other fault diagnosis
Interfaces with standard security software systems
New chemical signatures added to database via software
On-board, full system confidence tester activated at user defined intervals
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Perimeter protection
HVAC systems
Railway platforms
Ports
Airports
Stadiums
Chemical manufacturing and storage facilities
Manufacturing facilities
Environmental monitoring
Schools
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Typical Applications
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Benefits Return on Investment
Large area coverage Low cost per area covered
One detector indentifies multiple chemicals Low cost per chemical sensed Few sensors required
No scheduled maintenance Low ownership costOn-board, full system confidence testerUntrained Operators
Integration with existing control systems Low integration costsNo specialized software required
Software updatable Add latest chemical threatsModify alert levels or alarms remotely
Long-term data storage ForensicsMonitor against long-term threats (ramp-up)
Return on Investment
Designated a Department of Homeland Security SAFETY Act Qualified Anti-terrorism Technology (QATT)
Metro Rail
Industrial Installations
Carbonated beverage manufacturing
Defense Logistics Agency
Institutional Ventilation
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Reference Supporters
Army/Edgewood Research
Office of Naval Research
Private Entities
Technical Support Working Group (TSWG) and DHS/DOS
University of Virginia
Virginia Center for Innovative Technology
Technology Heritage
Mahalanobis Distance Technique
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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 detection
the mathematical proximity to signatures in the chemical database for identification
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Prasanta Chandra Mahalanobis
Mahalanobis Distance
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Ammonia at 70°F/30% RH, 30 sec averaging
Mahalanobis 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™.
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Uniqueness of ChemVECTOR™
Physical and Software Schematics
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ChemSight™ Detection and Identification
DetectionDetection 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.
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Internal Layout of ChemSight™
3) Band pass filters parse spectrum and send signals
for processing
3) Band pass filters parse spectrum and send signals
for processing
2) Rotating Mirror concentrates light on detector array
2) Rotating Mirror concentrates light on detector array
1) IR Light Enters Detector
1) IR Light Enters Detector
ChemSight™ Optical Layout
7.0”
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7.5”
22.5”
ChemSight™ Detector Dimensions
ChemSight™ Source Dimensions
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14”
14”
8”