Project Number: 6208-21410-005-09
Project Type: Reimbursable

Start Date: Feb 01, 2004
End Date: Jan 31, 2006

Objective:
The goals of the proposed research are to theoretically and experimentally define the inherent errors associated with EPA approved PM10 and PM2.5 stack samplers. The specific objectives include: (1) Conduct theoretical simulations to estimate the errors due to the interaction of particle size and sampler performance characteristics of EPA approved PM10 and PM2.5 stack samplers. (2) Conduct theoretical simulations to estimate the errors due to PM10 and PM2.5 stack sampler performance characteristics that vary beyond EPA's defined performance criteria. (3) Experimentally determine the sampling errors associated with EPA approved PM10 and PM2.5 stack samplers. Determine the errors due to the interaction of particle size and sampler performance characteristics using dusts with various particle size distribution characteristics. Determine the variations in the PM10 and PM2.5 stack samplers performance characteristics using dust with various particle size distribution characteristics. (4) Compare the experimental data with the results of the theoretical simulations and explore theoretical methods of predicting the variations in the stack sampler performance characteristics due to particle size and loading.

Approach:
For Objective 1: These simulations will be conducted to determine the theoretical ratios of sampler to true concentrations for a range of PSD and sampler performance characteristics. Lognormally distributed PSDs that are characterized by MMDs ranging from 1 to 40 micrometers and GSDs ranging from 1.3 to 2.5 will be used in the simulations. The PM10 sampler performance characteristics used will correspond to EPA's defined performance criteria. The PM2.5 sampler performance characteristics will be based on EPA's defined cut-point range and slopes reported in the literature. For Objective 2: A simulation will be conducted to determine the errors due to PM2.5 stack sampler performance characteristics that vary beyond EPA's defined performance criteria. The cut-points will be varied from 1 to 5 micrometers and the slope will be varied from 1.2 to 2.5. For Objective 3: A dust entrainment system will be designed, constructed, and evaluated to use in the stack sampling tests. This system will be composed of a steel or aluminum disk with a small channel milled around the top perimeter of the disk. The channel will be approximately 1 inch from the outer edge of the disk. This channel will be used to control the volume (mass) of dust entrained in the air stream. The disk will be mounted to a variable speed drive so that as the disk rotates, more dust can be introduced into the air stream. An extension will be constructed to extend the distance between the cyclone nozzle and the cyclone. This extension will provide added flexibility in conducting the tests. With the exception of the extension, the Method 5 stack sampler with the stack sampling cyclones will be operated based on EPA procedures. The filters used will be Teflon due to the large particle backgound count associated with quartz or glass fiber filters. The sampler's airflow rate will be closely monitored to assure that the airflow rates remain constant during individual test runs. Dusts used in the project will be fly ash, aluminum oxide, Arizona road dust, wheat flour, corn starch, and two other starches. Tests will be broken down into the following parameters: loading, air flow rate, dust, and replications. Once the tests are completed, a gravimetric and particle size analyses will be conducted. Results will be used with the known loading rates and particle size distribution associated with the entrained dust to determine the sampling errors and to calculate the penetration curve associated with the cyclone(s) being evaluated. For Objective 4: Experimental data will be compared with the theoretical simulation results to determine if the experimental data falls within the range of errors associated with the theoretical simulation results. If the two data sets agree, the experimental data will be evaluated to determine an additional algorithm that can be incorporated into theoretical model in order to predict shifts in the sampler performance characteristics due to particle size, particle loading, and sampler airflow rate. Once the model is updated, additional stack sampling tests will be conducted to validate the theoretical model.

Project Team

Buser, Michael - Mike Holt, Gregory

Related National Programs

Quality and Utilization of Agricultural Products (306)