Chemical agent detection

• US 20070161111A1
• Filed: 09/26/2006
• Published: 07/12/2007
• Est. Priority Date: 05/11/2004
• Status: Active Grant

• Current Assignee: Leidos, Inc. (Leidos Holdings, Inc.)
• Original Assignee: Science Applications International Corporation
• Inventors: Rose, David, Ha, James, Haupt, Steven
• Granted Patent: US 7,941,288 B2
• Time in Patent Office: Days
• US Class Current: 436/43
• CPC Class Codes: G01N 27/00 Investigating or analysing materials by the use of electric, electrochemical, or magnetic means G01N3/00 – G01N25/00 take precedence; measurement or testing of electric or magnetic variables or of electric or magnetic properties of materials G01R
• CPC Class Codes: G01N 33/0036 Specially adapted to detect a particular component all the other sub-groups of G01N33/0004 take precedence
• CPC Class Codes: Y10T 436/11 Automated chemical analysis

Abstract

A chemical agent detector with a a lesser demand sensor, a greater demand sensor, an inlet; and a manifold; and methods associated therewith. The manifold is positioned between the inlet and the sensors, and includes a first intake associated with the lesser demand sensor, a second intake associated with a greater demand sensor, and at least one restrictor. The first intake is placed closer to the inlet than the second intake, and the second intake is isolated from the inlet by at least one restrictor within the manifold. The intakes and restrictor are sized and positioned such that the ratio between: the conductance of the path from the inlet to the greater demand sensor to the conductance of the path between the sensors effectively isolates the lesser demand sensor from the effects of the greater demand sensor.

Claims

1. In a chemical agent detection system comprising a plurality of sensors, at least one first sensor operative to adjust its baseline to compensate for changes in ambient levels of a chemical agent and at least one second sensor not operative to so compensate, a method for mitigating desensitization of the first sensor, the method comprising:

where the first sensor has at least once adjusted its baseline, and where the second sensor indicates the presence of a chemical agent from among chemical agents common to the capabilities of both sensors and the first sensor does not indicate the presence of the chemical agent;

adjusting the first sensor to a prior baseline and retaining this adjusted baseline if the first sensor alarms in the presence of the chemical agent with the adjusted baseline.

2. The method of claim 1 further comprising the step of using a feedback mechanism, wherein a baseline of the at least one second sensor after sensing the chemical agent is fed through the feedback mechanism to the at least one first sensor to mitigate false desensitization of the at least one first sensor.

3. The method of claim 2 wherein initiating the feedback mechanism occurs when the at least one second sensor senses the chemical agent, triggering the at least one first sensor to reevaluate its alarm status by using a clean environment baseline.

4. The method of claim 1 further comprising the step of supplying the plurality of sensors with air from one inlet source.

5. The method of claim 4 further comprising the step of balancing the flow and volumetric demands of the plurality of sensors.