ENSC41 Silica Sampling Cassette
Team Members: Michael Sedor, Ryan Rackham,
Jacob Adams, Peter Siderius
Faculty Advisor: Art Miller
Sponsor: NIOSH-CDC Western States
Project Overview: Mine workers are exposed to respiratory hazards in the form of airborne particles, including silica, which causes silicosis in exposed workers. NIOSH research to reduce silicosis in miners includes studies to improve in-field silica measurement methods. Collecting silica-bearing dust for analysis is typically done by collecting samples onto filters for lab-based analysis, but no field-portable method exists to quantitate the silica on such samples. In order to achieve this, NIOSH is investigating the use of field-portable FTIR spectrometers. This approach has the benefit of portability, but current spectrometers do not incorporate a user-friendly method for sample presentation. The goal of this work is therefore to develop a sampling and analysis system that will allow a current FTIR instrument (Bruker Alpha) to be used easily to fill the need for a more portable sampler for mining applications, and package it in a way that is user friendly, mine-worthy and functional for collecting and analyzing mine dust samples.
Summary Statement of Project Goal: The goal of this project is to develop a filter-sampling cassette that can be easily placed into an FTIR instrument for analysis (minimal disassembly or sample preparation by the user). The cassette must incorporate the use of standard 37mm filters and allow FTIR analysis of the sample using “transmission” mode, without removing the filter i.e. the filter must stay attached to some part of the cassette, to simplify handling by the user. The work will entail four tasks: 1) Design and build a new style sampling cassette that improves upon existing designs, and can be used with existing dust cyclones.
2) Once the cassette is built and tested, a cassette-holding fixture must be designed to fit the current FTIR platform, and allow easy placement of samples for analysis.
3) Based on the first iteration, design/build an additional sampling cassette that is designed to deposit most of the silica dust onto a localized region near the center of the filter, or that uses a smaller filter. The second design must also be amenable to use with existing cyclones, and should use the same cassette-holding fixture.
4) Assist in the design and testing of user-friendly software interface (to be written by another CEDE team, possibly with assistance from Bruker Engineers) that runs seamlessly with the FTIR spectrometer software. The software must be designed for use in combination with the sampling/analysis “system”.
The team will collaborate with the other GU design team to draft and refine the key elements required for the software.
Project Deliverables: The project team will study the two current designs for filter cassettes and sample holders and develop at least three potential new preliminary designs for a sampling and analysis system. After evaluation of the preliminary designs, an optimized design will be developed and design drawings will be made and a prototype built and tested. The prototype will be tested using lab-generated aerosols, to insure that performance is comparable or better than previous designs. One of the issues involved is that typical designs incorporate a backing pad or backing “grid/screen” that if mounted together with the filter, makes the FTIR transmission method impossible. The new design must allow transmission FTIR analysis, so must replace the backing pad or make it separable from the filter, and optimally have it not affect the deposition pattern of dust on the filter, and/or the accuracy of the analysis. The NIOSH/OMSHR-Spokane staff will provide suitable test facilities, consultation, and various fabrication and testing materials. The results of this research will enable the application of FTIR spectrometry on dust samples collected in mines, by users unfamiliar with FTIR spectrometry. Results will also be of interest to many researchers and industrial hygienists who work in the field of aerosols and airborne contaminants, especially those containing silica.