AN EXPERIMENTAL STUDY OF OSCILLATING FLOW WITH ABSORBENT POLYMERS FOR USE IN RESPIRATORS

A respirator system involving alternating flow (inhaling and exhaling) through a perforated polymer filter was examined to determine the potential for savings in weight and bulk of respirators. Experimental testing included measurements of breakthrough times and toxic vapor removal efficiencies of polymer modules constructed with multiple parallel channels having variations in length and radii. Flows through the channels were cycled sinusoidally and mean velocities as well as the cycle periods were varied. The entering air contained measured concentrations of vapor to be filtered while the return air contained none. Flame ionization detectors were used to measure exiting concentrations as functions of time. The oscillating,, flow system was found to reach an equilibrium state for which exiting mearr concentration reached a steady value at a fraction of the entering concentration. Measurernents of partition coefficients and diffusion coefficients were made for various polymers using the vapors of dimethylmethyl-phosphonate and toluene. Partition coefficients were found to vary from one polymer to another by orders of magnitude and polyr,ners tested showed decreases with temperature over the range from 20 to 37 degrees centigrade important for two way breathing systems. The reverse scavenging of absorbed vapors has been shown to be effective and offers potential for further development of more efficient systems.