System and method for performing quantifiable release spore testing on bioaerosol detection technologies

• US 7,343,782 B2
• Filed: 04/10/2006
• Issued: 03/18/2008
• Est. Priority Date: 04/10/2006
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Damer, Kenneth S., Radcliff, Edmond G.
• Primary Examiner(s): Larkin; Daniel S.
• Assistant Examiner(s): Rogers; David A.
• Application Number:
  US11/400,237
• Publication Number:
  US 20070234777A1
• Time in Patent Office: 708 Days
• Field of Search: 73/10.1, 73/10.2, 73/12.4, 73/310.2, 73/280.1, 73/310.5
• US Class Current: 73/31.03
• CPC Class Codes: G01N 1/2205 with filters
• CPC Class Codes: G01N 1/2247 Sampling from a flowing stream of gas
• CPC Class Codes: G01N 15/0205 by optical means
• CPC Class Codes: G01N 2001/2223 aerosol sampling devices
• CPC Class Codes: G01N 2001/225 isokinetic, same flow rate for sample and bulk gas
• CPC Class Codes: G01N 2015/019 Biological contaminants; Fouling
• CPC Class Codes: G01N 33/0036 specially adapted to detect a particular component physical analysis of gaseous biological material G01N33/497
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

A system for testing devices for detecting airborne particulate matter generates a first airflow and a second airflow. The second airflow is filtered to remove ambient airborne particulate matter from the second airflow, and particulate matter to be detected is aerosolized and introduced into the second airflow. The second airflow is sampled by an optical particle counter to determine an amount of particulate matter released into the second airflow. The first and second airflows are combined, and the combined airflows are sampled by one or more detecting devices to be tested. Detection results of the tested detecting devices are compared with the amount of particulate matter released into the second airflow as determined by the optical particle counter to assess the accuracy and functionality of the detecting devices.

Claims

1. A system for testing a device for detecting the presence of airborne particulate matter comprising:

a primary airflow conduit constructed and arranged to generate a primary airflow;

a secondary airflow conduit constructed and arranged to generate a secondary airflow;

a filter operatively positioned with respect to the secondary airflow to remove ambient particulate matter from the secondary airflow;

a particulate aerosol generator constructed and arranged to generate an amount of airborne particulate matter and to release the generated airborne particulate matter into the filtered secondary airflow;

an apparatus for measuring the amount of airborne particulate matter released into the secondary airflow; and

an airflow combination location where the primary and secondary airflows are combined;

wherein the device for detecting the presence of airborne particulate matter is tested by positioning it operatively with respect to the combined primary and secondary airflows so that it can detect the airborne particulate matter that was originally released into the secondary airflow.

3. The system of claim 1, wherein said a particulate aerosol generator comprises:

a particulate container;

particulate flow conduit connected to said container and having a terminal end within the secondary airflow;

a source of gas under pressure, said source being in communication with said container and said particulate flow conduit to generate gas flow in said conduit in which particulate matter from the container is entrained; and

valve constructed and arranged to control flow of gas through said particulate flow conduit.

4. The system of claim 3, wherein said particulate aerosol generator further comprises a variably-sized orifice in a portion of said particulate flow conduit.

5. The system of claim 3, wherein said valve comprises an electronically controlled valve.

6. The system of claim 3, wherein said source of gas under pressure comprises a vessel containing a compressed inert gas.

7. The system of claim 6, wherein the inert gas is selected from the group consisting essentially of nitrogen, argon, and neon.

2. The system of 1, wherein said apparatus for measuring the amount of airborne particulate matter released into the secondary airflow comprises an optical particle counter.

8. A method for testing a device for detecting the presence of airborne particulate matter comprising:

generating a first airflow;

generating a second airflow;

filtering the second airflow to remove ambient particulate matter from the second airflow;

generating an aerosol of particulate material to be detected by the device for detecting; and

injecting the aerosol into the filtered second airflow;

quantifying the particulate material injected into the second airflow of air;

combining the first and second airflows to create a combined airflow; and

measuring the combined airflow with the device for detecting to be tested.

9. The method of claim 8, further comprising introducing other interferent substances that may be present in the intended operational environment into the first airflow.

10. The method of claim 8, wherein the first airflow is generated so as to simulate ambient conditions in which the device for detecting is intended to be used.

11. The method of claim 8, wherein generating an aerosol comprises:

directing a gas flow relative to a source of particulate matter so as to entrain a portion of the particulate matter in the gas flow;

transmitting the gas flow with particulate matter entrained therein through a conduit terminating within the second airflow; and

controlling the gas flow via a valve so as to control the amount of entrained particulate matter released into the second airflow.

12. The method of claim 8, wherein measuring the particulate material injected into the second airflow of air comprises sampling the second airflow by collecting an amount of the second airflow and directing the collected amount into an optical particle counter.

13. A system for testing a device for detecting the presence of airborne particulate matter comprising:

means for generating a primary airflow;

means for generating a secondary airflow;

filter means operatively positioned with respect to the secondary airflow to remove ambient particulate matter from the secondary airflow;

a particulate aerosol generating means for generating an amount of airborne particulate matter and for releasing the generated airborne particulate matter into the filtered secondary airflow;

particulate measuring means for measuring the amount of airborne particulate matter released into the secondary airflow; and

means for combining the primary and secondary airflows;

wherein the device for detecting the presence of airborne particulate matter is tested by positioning it operatively with respect to the combined primary and secondary airflows so that it can detect the airborne particulate matter that was released into the secondary airflow.