Abstract: A method for reading and analyzing a diffusion-cell colorimetric exposimeter for making a quantitative determination of the time-weighted average (TWA) exposure to airborne gases or vapors. The diffusion cell is optically scanned to form color video signal data representative of the primary color components of the image formed from the reaction of the chromophoric reagent and pollutant. The data is converted to digital data and processed to compute exposure for a given pollutant gas as a function of color intensity for at least one of the primary color components.

Abstract: A reciprocating piston flow meter for measuring gas flow through the flow meter comprising a hollow precision bore flowtube in a vertical orientation, with a movable piston containing a valve assembly for movement in concert with the piston between one position at or near the bottom end of the flowtube, and an elevated position at or near the upper end of the flowtube. The valve assembly is mechanically activated at each opposite end of the piston stroke to permit the piston to reciprocate between each opposite end in response to the presence of a gas flow.

Abstract: A soap film gas flow measuring device for computing the rate of gas flow through the device by detecting each moment in time when a soap film crosses two positions in a flow tube through which the soap film is propelled by the gas flow, computing the time difference and calculating the flow rate. A set of insulated wire conductors is inserted through the flow tube at each position at which the soap film is to be detected and circuit means is used to detect a predetermined drop in conductivity between each set of conductors corresponding to the crossover point.