US 3,945,801 AGranted

Indicator providing continuous indication of the presence of a specific pollutant in air

AssigneeThe United States of America as represented by the United States National Aeronautics and Space Administration Office of General Counsel-Code GP

InventorsJames C. Administrator of the National Aeronautics and Space Administration, with respect to an invention of Fletcher, Charles G. Miller, Ralph E. Bartera

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Abstract

A continuous HCl in-air indicator consists of a tube-like element with an inlet end through which a continuous stream of air, containing HCl, enters. The air flows downstream from the inlet end and exits the element's outlet end. Positioned between the element's inlet and outlet ends are first and second spaced apart photoelectric units, which are preferably positioned adjacent the inlet and outlet ends, respectively. Ammonia gas is injected into the air, flowing through the element, at a position between the two photoelectric units. The ammonia gas reacts with the HCl in the air to form ammonium chloride particles. The difference between the outputs of the two photoelectric units is an indication of the amount of HCl in the air stream.

Claims3

Dependent claims

A device for indicating the amount of a specific pollutant present among various pollutants in a stream of air comprising:

a single elongated hollow tube-like element having a first open end and a second open end, diametrically opposite said first open end, said first open end defining an inlet end through which a continuous stream of air containing various pollutants, including a specific pollutant, is adapted to enter and flow continuously downstream along the entire length of said element and exit through said second end defining an outlet end of said element;
a first photoelectric unit positioned upstream from said outlet end and including a first light source and first light sensitive means, positioned directly in the path of light from said source, for receiving the light directly directed thereto from said first light source, said first light sensitive means being spaced apart from said first light source in a direction perpendicular to the element's length direction along which the air flows from said inlet end to said outlet end, so that at least a portion of the air flowing through said element passes between said first light source and said first light sensitive means, the latter providing an output which is a function of the light directed thereto from said first light source and the light transmission characteristics of the air with the various pollutants including said specific pollutant contained therein;
and
source means for injecting selected matter into the air flowing through said element at a location upstream from said first photoelectric unit, whereby the selected matter reacts inside said element with the specific pollutant in said air to form compound particles carried by said air past said first photoelectric unit, the air with said compound particles having light transmission characteristics which differ from those of the air with the specific pollutant therein.

1 more element

A device for measuring the amount of a selected first compound present in a continuous stream of a carrier gas essentially consisting of:

a single elongated hollow tube-like element having a first open end and a second diametrically opposite second open end, the distance between said open ends defining the length of said element, said first open end defining an inlet end through which a continuous stream of a carrier gas containing said first compound is adapted to flow continuously downstream along the entire length of said element and exit through said second open end, which defines an outlet end of said element;
a single photoelectric unit positioned upstream from said outlet end and including a single light source and a single light sensitive means, spaced apart from said single light source in a direction which is substantially perpendicular to the element's length direction, along which the carrier gas flows from said inlet end to said outlet end, so that at least a portion of said carrier gas passes between said single light source and said single light sensitive means, the latter being positioned directly in the path of light from said light source, for providing an output which is a function of light which is directly directed thereto from said single light source and the light transmission characteristics of the carrier gas and any compounds carried therein;
source means including an outlet nozzle in communication with said element for injecting discrete quantities of a selected second compound into said element, through which said carrier gas with said selected compound flow, during discrete intervals, spaced apart by periods during which said selected second compound is not injected into said element, said first and second compounds reacting in said element to form therein particles of a selected third compound, which are carried by said carrier gas past said single photoelectric unit, the light transmission characteristics of said carrier gas with particles of said third compound being different from the light transmission characteristics of said carrier gas with said first compound;
and
output means coupled to said single light sensitive means for sensing the output thereof.

2 more elements

Dependencies are inferred from the claim text.