Minneapolis, MN: U.S. Department of the Interior, Bureau of Mines, TN 410, 1992 Oct; :1-2
Objective: Develop a cost-effective diesel aerosol sampler that can be used by industry and regulatory agencies to determine the diesel exhaust aerosol concentration in mine atmospheres. The sampler must be easy to use, wearable by mine personnel, compatible with current personal sampling protocols, and inexpensive. Approach: The University of Minnesota (University) and the U.S. Bureau of Mines (USBM) have developed and tested a prototype diesel exhaust aerosol sampler. The sampler, however, was complicated and expensive to fabricate. Consequently, the USBM redesigned the sampler to simplify both manufacturing and use, and the sampler was evaluated to ensure equivalency with the prototype. Background: The National Institute for Occupational Safety and Health (NIOSH) has recommended that "whole diesel exhaust be regarded as a 'potential occupational carcinogen, as defined in the Cancer Policy of the Occupational Safety and Health Administration." In addition, the U.S. Mine Safety and Health Administration (MSHA) has been directed by an advisory committee to establish a diesel exhaust aerosol standard and regulations to minimize exposure to diesel pollutants in underground coal mines. Both reports point out the need for development of measurement techniques for respirable diesel aerosol, and the MSHA report specifically requests support from the USBM and NIOSH to develop these techniques. How It Works: The USBM, in cooperation with the University, has conducted studies of coal aerosol in both the laboratory and underground coal mines. These studies have shown that respirable coal dust and diesel aerosol can be differentiated by size. The measured particle size distribution has two maxima or modes with the primary mode separation at 0.8 pm. Diesel aerosol has been shown to be predominately less than 0.8 pm in size and coal dust greater than 0.8 pm in size. Based on this, the University designed a three-stage sampler that preselects for respirable aerosol and then separates this into two parts by size. These sizes are greater and less than 0.8 microm. This sampler utilizes a 10-mm Dorr-Oliver cyclone, a 0.8-microm cut point impactor, and an after-filter. The impactor and after-filter are housed in one unit. The University sampler was designed to minimize sample loss. Minimizing manufacturing cost was not a primary design goal. It is commercially available for a cost of $1,500. Retaining the internal geometry of the University sampler, the USBM modularized the design by separating the impactor section and filter. As shown in figure 3, the impactor section can be added to a commercially available sampler assembly to complete the diesel sampler. The cost objectives were satisfied: The impactor section can be manufactured in quantity for approximately $10 and would sell for less than $60. The sampler assembly would have a commercial cost of approximately $150. Testing the Design: The USBM sampler was shown to be equivalent to the University sampler when the two were tested together. The comparative tests included impactor cut point impactor losses, and an overall field evaluation in an underground coal mine.
Minneapolis, MN: U.S. Department of the Interior, Bureau of Mines, TN 410