Development of a field method for determining the service lives of respirator cartridges--Part IV: Results of field validation trials.
Results of a fourth study on the use of small, carbon-filled glass tubes, referred to as respirator carbon tubes (RCTs), for predicting the service lives of organic vapor respirator cartridges are presented. Organic vapors are drawn through the RCT by using a personal sampling pump until breakthrough is detected. This breakthrough time is then used in conjunction with a bed-residence adsorption model to predict the breakthrough time of a cartridge containing carbon identical to that in the RCT. Previous laboratory work demonstrated that accurate prediction of cartridge breakthrough time was possible for exposure to carbon tetrachloride in atmospheres containing 5-94% relative humidity (RH) with both dry and prehumidified carbon beds and with n-hexane, pyridine, and binary mixtures of each with carbon tetrachloride. This report examines the performance of the RCT method in a workplace environment where carbon tetrachloride concentrations varied from 101 to 855 ppm, pyridine levels varied from 0 to 29 ppm, temperatures ranged from 28 to 39 degrees C, and RH varied from 19% to 49%. The RCT method predicted cartridge breakthrough times to an accuracy of +/- 8 at the 95% confidence level, which equaled or exceeded results of previously reported laboratory studies. Actual breakthrough times averaged within +/- 5% of times predicted with previous laboratory data. A plot of bed-residence time versus breakthrough time yielded a coefficient of determination of 0.71 when ambient concentrations were standardized.
Cohen
H J
HJ
Department of Environmental and Industrial Health, School of Public Health, University of Michigan, Ann Arbor 48109-2029.
Levine
S P
SP
Garrison
R P
RP
D000395:Air Pollutants, Occupational / Q000032:analysis*; D002251:Carbon Tetrachloride / Q000032:analysis*; D004784:Environmental Monitoring; D006801:Humans; D012134:Respiratory Protective Devices; D013997:Time Factors
D000395:Air Pollutants, Occupational; D002251:Carbon Tetrachloride