Abstract: A transparent glass detection tube contains a bed of silica gel which has been impregnated with sulfuric acid. One end of the tube is open to the outside air while the other end is connected to a sampling pump. Outside air is drawn through the tube and aldehydes and moisture in the air are separated and adsorbed on sequential lengthwise portions of the gel bed. At the end of the sampling period, xylene vapors are drawn through the silica gel forming a brownish tint stain on that portion of the bed that has adsorbed aldehydes. The length of the stain is a measure of the amount of aldehydes present in the air sample, i.e. the dosage exposure to aldehydes during the sampling period.

Abstract: A gas dosimeter comprises a stack of porous sheets, impregnated with a reagent that changes color on contact with the gas to be determined, contained in a housing which has an opening to expose one end of the stack to the atmosphere to be tested. The gas to be determined penetrates by diffusion the layers of porous sheets, causing the sheets in the stack to change color sequentially from the end of the stack exposed to the atmosphere. The degree of penetration through the layers of porous sheets is a function of dosage exposure. The housing may be transparent with each superposed sheet in the stack being larger than the adjacent underlying sheet, so that each sheet is visible through the housing endwall.

Abstract: A gas dosimeter comprises a strip substrate coated or impregnated with a color-changing reagent; the strip is disposed lengthwise in a transparent tube, one end of which is openable and is spaced by a diffusion path from one end of the strip. When the dosimeter tube is opened and exposed to the atmosphere containing detectable gas, a color change develops lengthwise of the strip dependent on the dosage exposure to the gas.