Evaluation of a self-cleaning portable dust collector for reducing worker exposures to silica at hydraulic-fracturing sites

ABSTRACT

National Institute for Occupational Safety and Health (NIOSH) researchers continue to study worker exposure to respirable crystalline silica (RCS) and develop interventions to reduce these exposures. Occupational overexposures to RCS continue to cause illness and deaths in many industries and RCS has been identified as a serious exposure risk associated with hydraulic- fracturing operations during oil and gas extraction. In 2016 the Occupational Safety and Health Administration (OSHA) reduced the permissible exposure limit (PEL) to 0.05 milligrams of silica per cubic meter of air, averaged over an 8-hour day. This mandate requires hydraulic-fracturing operations to implement dust controls and safer work methods to protect workers from silica exposures above this PEL by June 23, 2021. At hydraulic-fracturing sites utilizing sand movers, pneumatic transfer of fracking sand is the primary source of aerosolized RCS. Currently, there are limited commercially available engineering controls for the collection of dust emitted from thief hatches on sand movers. The goal of this research is to develop a robust, cost-effective, weather resistant, portable, self-cleaning dust collection system that can be retrofitted onto sand mover thief hatches. A prototype was designed, built, and tested, and it was determined that the system could handle flows in the range of 600 to 1300 cfm with loading/cleaning cycle times of 40 and 5 minutes respectively and demonstrated operating efficiencies of 97–99%. Further development of this NIOSH prototype is being done in collaboration with an industry partner with the goal of developing a commercially viable, cost-effective solution to reduce RCS at hydraulic-fracturing sites around the world.

Implications: This research has verified that airborne dust created by pneumatic transfer of fracking sand can be effectively collected using a passive cartridge filter system, and that the filters can be cleaned using blasts of air. Mounting these units to the thief hatches of sand movers will significantly reduce dust emissions from sand movers on hydraulic fracturing sites. Thus, this system offers the Oil and Gas Industry a method to reduce worker exposure to RCS on hydraulic fracturing sites that utilize sand movers. The success of this prototype has led researchers to devise a modified version for collecting dust at conveyor transfer points.

Acknowledgment

The authors would like to thank David Koski for his efforts in designing system components, creating mechanical drawings, and providing technical support, and the JM Huber Corporation for donating the Mining Safety Dust used for the tests in this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Disclaimer

The findings and conclusions in this manuscript are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Data availability statement

The data that support the findings of this study are available from the corresponding author, GWK, upon reasonable request.

Additional information

Funding

The work was supported by the Federally Funded Research .

Notes on contributors

Grant King

Grant King is a Mechanical Engineer who has worked in the Health and Safety Research Field for more than 30 years. His specialties include electro-mechanical systems integration, machine guarding, robotics, and machine design. Lately, his efforts have been aimed at improving airborne dust collection at hydraulic fracturing sites. His professional endeavors have predominately focused on improving worker safety in the Oil and Gas, Commercial Fishing, Mining, and Robotics Industries.

Arthur Miller

Arthur Miller is a PhD engineer who conducted mine safety research at NIOSH for over 30 years. He has a broad background in Civil, Aeronautical and Mechanical engineering, and his specialty is air quality. His many publications cover topics including dust, diesel particulate matter (DPM), silica and nanoparticles, and the focus was often on methods of measuring and characterizing airborne contaminants. He is currently working for NIOSH as a technical consultant.

Carl Schneider

Carl Schneider is an electrical engineer who graduated from Eastern Washington University. His specialties include: developing control and communication systems, electro-mechanical systems integration, and data-acquisition solutions. He has also designed and implemented multiple Internet of Things solutions for use in the industrial mining environment. These included implementing end to end (sensor to internet) communication solutions for various network topologies, as well as analyzing and presenting data visualizations and models associated with that system.

Greg Feagan

Carl Schneider is an electrical engineer who graduated from Eastern Washington University. His specialties include: developing control and communication systems, electro-mechanical systems integration, and data-acquisition solutions. He has also designed and implemented multiple Internet of Things solutions for use in the industrial mining environment. These included implementing end to end (sensor to internet) communication solutions for various network topologies, as well as analyzing and presenting data visualizations and models associated with that system.

Greg Feagan is an engineering technician for the NIOSH Spokane Mining Research Division. He studied electronics and instrumentation in the US Air Force and worked in the aviation and electronics industries for ten years. He then worked in a manufacturing environment for thirteen years producing engineering plans, documents, and software. He has assisted in numerous lab and field research projects related to mining industry safety.

Darby Gain

Greg Feagan is an engineering technician for the NIOSH Spokane Mining Research Division. He studied electronics and instrumentation in the US Air Force and worked in the aviation and electronics industries for ten years. He then worked in a manufacturing environment for thirteen years producing engineering plans, documents, and software. He has assisted in numerous lab and field research projects related to mining industry safety.

Darby Gain has a B.S. in Aerospace Engineering with a concentration in Astronautics. She recently graduated from Embry-Riddle Aeronautical University. She completed an internship at NIOSH under the instruction of Dr. Arthur Miller where she contributed to the testing of the self-cleaning portable dust collector and the technical report.