CHARACTERISTICS OF AIR FILTER MEDIA USED FOR MONITORING AIRBORNE RADIOACTIVITY

A comparison was made of the more important characteristics of the available filter materials which are currently in use by various systems for monitoring airborne radioactivity throughout the world. Most of the materials described are commercially available the information herein is presented with the hope that it will be of use to those whose programs involve the employment of air-filter media or who require such information for the design of air-filter systems. The filter characteristics measured are such physical properties as tensile strength, thickness, density, ash content, retentivity toward 0.3 micron dioctyl phthalate DOP aerosol particles as a function of air velocity, retentivity toward airborne fission products and natural radioactive aerosols radon daughters at several air velocities, flow rate as a function of pressure drop across the filter, and the relative rates of clogging by atmospheric dust. The observation of a rapid change in flow with dust loading of some of the filter media suggests the systematic study of such changes as possibly a simple procedure for monitoring the dust content of the atmosphere.