Portable controlled air sampler

• US 5,333,511 A
• Filed: 03/23/1993
• Issued: 08/02/1994
• Est. Priority Date: 09/07/1990
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Administrator Of The United States Environmental Protection Agency
• Original Assignee: United States Of America As Represented By The Administrator Of The United States Environmental Protection Agency
• Inventors: Schweiss, Jon W., Boyum, Gerald A.
• Primary Examiner(s): NOLAND, THOMAS
• Application Number:
  US08/035,875
• Time in Patent Office: 497 Days
• Field of Search: 73/864.34, 73/864.35, 73/863.21-863.25, 73/863.31, 73/863.32, 73/863.33, 73/863.01, 73/31.01, 73/31.02, 364/496, 364/480, 364/483, 340/660, 340/662, 340/663, 323/299, 323/303, 323/364, 323/304
• US Class Current: 73/864.34
• CPC Class Codes: G01N 1/2205 with filters
• CPC Class Codes: G01N 1/2208 with impactors
• CPC Class Codes: G01N 1/2273 Atmospheric sampling
• CPC Class Codes: G01N 1/24 Suction devices G01N1/22 - G01N1/2294 take precedence
• CPC Class Codes: G01N 2001/2223 aerosol sampling devices
• CPC Class Codes: G01N 2001/2297 Timing devices

Abstract

A portable analyzer for obtaining samples from a monitored environment during different time intervals includes a pump energized by a rechargeable battery pack for drawing gas from the environment selectively into plural sample holding bags and an impact filter. The pump is programmed to control the time when the gas is drawn from the environment and for controlling the flow to the sample holders so that different ones of the sample holders are responsive to the materials at the same or different times. The pump may respond to electric pulses, causing pulses of air to be supplied to the sample holding bags. The pump derives pulses having a rate directly proportional to the number of pump cycles. The pump may also operate continuously with sampling of the gases being controlled electronically. Operation of the pump is prevented in response to the battery pack voltage dropping to a level such that the voltage is less than a predetermined value, necessary to provide a predetermined flow rate per pump cycle. Operation of the pump is also prevented if the gas flow rate drops below a predetermined level. These prevent features can be manually overridden.

Claims

1. Apparatus for obtaining gas samples from a monitored environment during differing time intervals comprising plural sample holders, means for drawing gas from the environment, valve means for supplying the drawn gas to the different sample holders at mutually exclusive times, and

means for programming the valve means on a chronological basis, said programming means including means for independently controlling for each of the different sample holders the time when said valve means starts supplying drawn gas to the sample holder, the time when said valve means stops supplying drawn gas to the sample holder, and the sample interval between when said valve means starts and stops supplying said drawn gas to the sample holder.

2. A portable device for obtaining samples from a monitored environment during differing time intervals comprising a rechargeable battery pack, means energized by the battery pack for drawing gas from the environment, plural sample holders for materials in the drawn gas, one of said sample holders being for particulates in the environment, others of said sample holders being for gases in the environment, and

said gas drawing means including programmed means for controlling the time the gas is drawn from the environment and for controlling the flow to the sample holders so that different ones of the sample holders are responsive to the materials at different times, said programmed means including means for independently controlling for each of the different sample holders the time when said drawing means starts supplying drawn gas to the sample holder, the time when said drawing means stops supplying drawn gas to the sample holder, and the sample interval between when said drawing means starts and stops supplying said drawn gas to the sample holder.

3. The device of claim 2 wherein the sample holder for the particulates is upstream of the sample holders for the gases, and the flow of gas to the sample holders for the gases is controlled so that the gas flows into only one of the gas sample holders at a time.

4. The device of claim 3 wherein said programmed means includes means for controlling said drawing means to direct gas drawn through said particulate sample holder at mutually exclusive times to one of said gas sample holders or back to the monitored environment.

5. The device of claim 3 wherein said programmed means includes means for controlling said drawing means to direct gas drawn through said particulate sample holder over the same time period or back to the monitored environment.

6. The device of claim 2 wherein the gas drawing means includes a pulsed cycling pump energized by the battery pack, the pump deriving pulses having a rate directly proportional to the number of cycles of the pump in drawing gas from the environment, and means responsive to the pulses for displaying an indication of the number of cycles of the pump in drawing gas from the environment.

7. The device of claim 6 wherein the gas drawing means includes means energized by the battery pack for deriving constant amplitude DC voltage pulses having predetermined interpulse intervals, the pump being responsive to the pulses to be driven at a rate determined by the rate of the pulses.

8. The device of claim 7 wherein the gas drawing means includes means for preventing operation of the pump in response to the battery pack voltage dropping to a level such that the amplitude of the pulses is less than a predetermined value.

9. The device of claim 8 further including means for visually signalling that the pump is not operating because the amplitude of the pulses is less than the predetermined value.

10. The device of claim 8 further including means for continuing to prevent operation of the pump after the battery pack voltage has initially dropped to below said level even though the battery pack voltage thereafter rises to a level such that the amplitude of the pulses would not be less than the predetermined value.

11. The device of claim 10 further including manually activated means for overriding the means for continuing to prevent pump operation.

12. The device of claim 2 wherein the programmed means includes an electronic clock module including a liquid crystal display and first and second manually controlled programming switches for controlling the time of day during different days of the week when the gas is drawn from the environment.

13. The device of claim 2 further including means for deriving first and second indications respectively representing voltage being in excess of and less than a predetermined value necessary to provide proper operation of the means for drawing, and means responsive to the indications for controlling the flow of current from the battery pack to the means for drawing so that (a) the battery pack initially supplies current to the means for drawing and continues to supply current to the means for drawing while the first indication is derived until the second indication is initially derived and (b) the flow of current from the battery pack to the means for drawing is prevented in response to derivation of the second indication and is prevented thereafter even though the battery pack voltage increases above the predetermined value.

14. The device of claim 2 wherein said programmed means includes means for controlling said drawing means to repeatedly start and stop the supplying of drawn gas to a first of said gas sample holders for programmed sampling intervals and means for independently controlling the time interval between each such sampling interval.

15. The device of claim 14 wherein said programmed means includes means for controlling said drawing means to direct a drawn gas to a second of said sample holders during the time interval between sampling intervals of said first gas sample holder.

16. The device of claim 14 wherein said programmed means includes means for controlling said drawing means to direct a drawn gas to a second of said sample holders at the same time as directing the drawn gas to the first of said sample holders.

17. The device of claim 2 wherein the gas drawing means includes a pump energized by a battery pack, the pump operates continuously, and the gas is admitted to the gas sample holders through programming of solenoid valves.

18. The device of claim 17 wherein the gas drawing means includes means energized by the battery pack for controlling solenoid valves to be open with different frequencies and intervals thereby filling the gas sample holders simultaneously, concurrently or at mutually exclusive time periods.

19. The device of claim 18 wherein the gas drawing means includes means for preventing operation of the pump in response to the battery pack voltage dropping to a level that is less than a predetermined value.

20. The device of claim 19 further including means for continuing to prevent operation of the pump after the battery pack voltage has initially dropped below said level even though the battery pack voltage thereafter rises to a level such that the amplitude of the pulses would not be less than the predetermined value.

21. The device of claim 20 further including manually activated means for overriding the means for continuing to prevent pump operation.

22. The device of claim 17 wherein the gas drawing means includes means for preventing operation of the pump in response to the gas flow rate dropping to a level that is less than a predetermined level.

23. The device of claim 22 further including manually activated means for overriding the means for continuing to prevent pump operation.

24. The device of claim 2 wherein the programmed means includes an electronic clock module including a liquid crystal display and programming switches for controlling the time of day and the days of the week when the gas is drawn from the environment.

25. The device of claim 2 wherein said programmed means includes means for controlling said drawing means to maintain a specified flow setting by measuring the drop in air pressure at the outlet of the flowmeter and by compensating for reasonable changes in ambient temperature and pressure.

26. Apparatus for obtaining gas samples from a monitored environment during differing time intervals comprising plural sample holders, means for drawing gas from the environment, means for filtering particles from the drawn gas, valve means for supplying the drawn gas to the different sample holders, and

means for programming the valve means on a chronological basis, said programming means including means for independently controlling for each of the different sample holders the time when said valve means starts supplying drawn gas to the sample holder, the time when said valve means stops supplying drawn gas to the sample holder, and the sample interval between when said valve means starts and stops supplying said drawn gas to the sample holder.