Gas detection device

• US 3,924,219 A
• Filed: 04/19/1974
• Issued: 12/02/1975
• Est. Priority Date: 12/22/1971
• Status: Expired due to Term

• Current Assignee: David L. Braun
• Original Assignee: David L. Braun
• Inventors: Braun, David L.
• Primary Examiner(s): Albritton, C. L.
• Application Number:
  US05/462,415
• Time in Patent Office: 592 Days
• Field of Search: 338/34,35 23/254E,255E 340/237R 200/61.03 73/19,23R
• US Class Current: 338/34
• CPC Class Codes: G01N 27/12 of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid , for detecting components in the fluid
• CPC Class Codes: G01N 33/0011 Sample conditioning in general G01N1/28

Abstract

A device for measuring the concentrations of a selected gaseous component in a mixture of gases comprises a detector material capable of reacting with the component to be monitored disposed in a chamber having an inlet. A porous gas flow attenuating sheet closes the end of the chamber distally, the detector substance and the mixture of gases being monitored to prevent impingement of moving gas upon said detector substance while permitting contact of ambient gas thereon. The device is useful in combination with a filter element, providing a means to monitor the remaining effective life of the filter and also as a detector useful for measuring the exposure of various articles and human beings to hazardous gases.

Claims

1. A device useful for measuring the amounts of at least one selected gas in an ambient gas mixture comprising:

a shallow chamber having one open end comprised of a side of said chamber;

a detector substance adapted to interact with the gas to be measured located within said chamber;

a porous gas flow attenuating sheet which allows passage of ambient atmosphere closing the open end of said chamber distally to and spaced apart from said detector substance to form a relatively placid layer of gas between said ambient gas mixture and said detector substance;

whereby the amount of said selected gas available to react with said detector substance is caused to be a function of diffusion through the placid layer of gas and is substantially independent of velocity of the gas mixture at the interface of the device with the ambient surroundings.

2. The device of claim 1 where said attenuating sheet is a fine mesh screen.

3. The device of claim 1 where said attenuating sheet is a microporous polypropylene film.

4. The device of claim 1 where said reactive substance is activated charcoal and the gas being monitored is an organic vapor.

5. The device of claim 1 where said attenuating sheet is a glass frit.

6. The device of claim 5 where said sheet has reactive substances contained therein reactive with certain gases thereby preventing said certain gases from entering the chamber.

7. A device for measuring cumulative concentrations of mercury vapor in a mixture of gases, which comprises an electrically insulating substrate having a shallow cavity therein, a thin, electrically coherent film of a metal capable of amalgamating with mercury disposed in said cavity on said substrate in elongated strip form, and a porous gas flow attenuating sheet which allows passage of ambient atmosphere over the said substrate adjacent to and covering said cavity, and spaced apart from said film of metal, to prevent impingement of moving air upon said film of metal whereby the amount of mercury vapor available to interact with the said film of metal is caused to be a function of the diffusion of said vapor and substantially independent of the velocity of the ambient air.

8. The device of claim 7 where the thin, electrically coherent film of metal is a noble metal.

9. The device of claim 7 where the thin, electrically coherent film of metal comprises a sTrip of metal which will amalgamate with mercury overlaid with a more noble metal which also amalgamates with mercury.

10. A device for measuring cumulative concentrations of mercury in gas, which comprises an electrically non-conductive supporting block having a shallow serpentine cavity therein;

a thin, electrically coherent film of gold in elongated strip form contained in said cavity; and

a diffusion grating having a plurality of diffusion channels with a length to diameter ratio of at least about 3;

1 disposed over said supporting block adjacent to and coextensive with said cavity and spaced apart from said gold film strip, said diffusion grating preventing the impingement of moving air upon said gold film strip.