Gaseous contaminate dosimeter and method
AssigneeAbcor, Inc.
InventorRobert L. Goldsmith
Life of this patent
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Abstract
A gaseous contaminate personal dosimeter which comprises a container; an inert porous thin barrier element forming one side of the container, the barrier element adapted to permit the diffusion of the gaseous contaminates that are to be determined into the interior of the container; and a gaseous contaminate-collecting medium within the container and positioned opposite the barrier element to collect gaseous contaminate diffused from the ambient atmosphere through the barrier element; and means to inhibit convection movement of the diffused gases within the container, whereby the dosimeter permits the determination of gaseous contaminate in proportion to ambient concentrations independent of ambient convection patterns.
Claims17
A passive gaseous contaminate dosimeter to determine the amount of gaseous contaminates in a gas stream, which dosimeter comprises in combination:
- a. a closed container;
- b. a gaseous contaminate collecting medium of a solid or liquid sorbent within the interior of the container, which medium sorbs or reacts with the gaseous contaminate, the amount of which is to be determined;
- c. an inert porous sheet barrier element forming a portion of at least one side of the container, which barrier element permits the diffusion freely of the gas stream containing the gaseous contaminate from the ambient atmosphere into the interior of the container;
- d. a dead air space between and separating the barrier element and the collecting medium;
- e. the barrier element characterized by having a low diffusional resistance to the gas stream with the gaseous contaminate relative to that of the dead air space to permit the collection on the collecting medium of gaseous contaminates which diffuse into the interior of the container in proportion to the average ambient concentration about the dosimeter, and substantially independent of the ambient convection patterns of the gas stream exterior to and about the dosimeter;
- and
- f. a plurality of passageways extending within the dead air space to provide mechanical support to the sheet barrier element.
A passive gaseous contaminate dosimeter to determine the amount of gaseous contaminate in a gas stream, which dosimeter comprises in combination:
- a. a small, light-weight, closed container adapted to be employed on or about the breathing zone of a user;
- b. a gaseous contaminate collecting medium composed of a sheet material impregnated with a solid or liquid sorbent within the container, which collecting medium sheet sorbs or reacts with the gaseous contaminate of the gas stream whose amount is to be determined;
- c. an inert porous thin sheet barrier element forming a portion of at least one side of the container, and which permits diffusion freely of the gas containing the gaseous contaminate into the interior of the container, the barrier element having a thickness of from about 0.001 to 8 cm, and a porosity of from about 50 to 95%;
- d. a dead air space between and separating the barrier element and the sheet collecting medium;
- a plurality of passageways extending within the dead air space to provide mechanical support to the sheet barrier element;
- and
- f. the barrier element characterized by having a low diffusional resistance to gaseous contaminates in the gas stream relative to that of the baffle dead air space to permit the collection on the collecting medium of gaseous contaminates from the gas stream in proportion to the average ambient concentration of the gas stream and substantially independent of the ambient convection gas patterns of the gas stream about the exterior of the dosimeter.
In a method of determining the amount of gaseous contaminates in a gas stream during a designated time period by a dosimeter, which dosimeter comprises in combination:
- a closed container;
- a gaseous contaminate collecting medium of a solid or liquid sorbent within the interior of the container, which medium sorbs or reacts with the gaseous contaminate, the amount of which is to be determined;
- an inert porous sheet barrier element forming a portion of at least one side of the container, which barrier element permits the diffusion freely of the gas stream containing the gaseous contaminate into the interior of the container a dead air space between and separating the barrier element and the collecting medium;
- and the barrier element characterized by having a low diffusional resistance to the gaseous contaminate relative to that of the dead air space, the method which comprises:
- a. diffusing a gas stream containing gaseous contaminate ambient and external of the dosimeter through the porous barrier element into the dead air space of the dosimeter;
- b. providing a stagnant gaseous diffusion barrier layer inside the chamber and adjacent the interior surface of the barrier element, which stagnant air layer is substantially unaffected by ambient and gaseous patterns exterior to the opposing side of the barrier element, the resistance to mass transfer and the stagnant gaseous layer within the container substantially exceeding the resistance associated with the convective mass transfer to the porous barrier element;
- c. providing a baffle element having a plurality of passageways as a mechanical support for the sheet barrier element extending between the barrier element and the collecting medium;
- d. sorbing the gaseous contaminates from the diffused gas stream within the dead air space onto the gaseous collecting medium;
- and, thereafter,
- e. determining the concentration of the gaseous contaminate so collected and so sorbed.
Dependencies are inferred from the claim text.