Open Path Detection of Hazardous Gases. Open path, non-contact chemical detection Multiple chemicals...

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

04/18/23 Avir Sensors Proprietary 2

Technology Overview

ChemSight™ Architecture


Based on infrared spectrometry operating in the 830-1250 cm-1 (fingerprint region) 2000-3300 cm-1 spectral ranges


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.

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)


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


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


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


Sensitive, Specific, Reliable, and Robust


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


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


true positive rate: TP/(TP+FN) {probability of identification}false-positive rate: FP/(TN+FP) {probability of false-identification}

Illustrative ROC Curves


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


75 ppm·m ammonia, 1 sec average

ChemSight™ ROC Curves


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


Perimeter protection

HVAC systems

Railway platforms

Ports

Airports

Stadiums

Chemical manufacturing and storage facilities

Manufacturing facilities

Environmental monitoring

Schools


Typical Applications


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


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


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


Prasanta Chandra Mahalanobis

Mahalanobis Distance


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™.


Uniqueness of ChemVECTOR™

Physical and Software Schematics


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.



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”


7.5”

22.5”

ChemSight™ Detector Dimensions

ChemSight™ Source Dimensions


14”

14”

8”

Open Path Detection of Hazardous Gases. Open path, non-contact chemical detection Multiple chemicals...

Documents

Transcript of Open Path Detection of Hazardous Gases. Open path, non-contact chemical detection Multiple chemicals...