The National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) conducted joint research to evaluate explosion blast effects on typical U.S. mine ventilation stoppings in the NIOSH Pittsburgh Research Laboratory's (PRL) Lake Lynn Experimental Mine (LLEM). An innovative Australian-designed brattice stopping was also evaluated. NIOSH findings and recommendations are detailed.

At the request of the Mine safety and Health Administration (MSHA) and the West Virginia Office of Miners' Health, Safety, and Training, the NIOSH's Pittsburgh Research Laboratory evaluated the effects of explosions on specific mine ventilation seals at its Lake Lynn Experimental Mine to assist the agencies in their investigations of the explosion at the Sago Mine in West Virginia, which occurred on January 2, 2006. Six full-scale explosion tests were conducted to help answer questions regarding possible scenarios for the Sago explosion. NIOSH's findings and recommendations are documented within.

This report presents nearly all structural data available from explosion tests of 20-psi mine ventilation seals and concrete-block ventilation stoppings that were conducted by the NIOSH during 1997-2008. Although the seals tested were designed to meet the former federal 20-psi pressure design standard, the structural information contained herein on these seal tests will facilitate the analysis and design of coal mine seals that meet the new explosion pressure criteria of 50 and 120 psi as set forth in the Mine safety and health Administration's final rule on "Sealing of Abandoned Areas."

nThe National Institute for Occupational Safety and Health (NIOSH)'s Pittsburgh Research Laboratory conducted a full-scale test of a composite polyurethane-aggregate seal in a hydrostatic chamber at the Lake Lynn Experimental Mine. The report details the test results of the composite polyurethane-aggregate seal and provides an analysis of those results in terms of the seal's structural behavior.

The National Mining Association and the Mine safety and Health Administration requested that the National Institute for Occupational Safety and Health (NIOSH) conduct full-scale evaluations of a recently developed carbon fiber-reinforced polymer (CFRP) reinforcement technique for upgrading existing mine ventilation seals to withstand an explosion pressure of 50 psi or greater. The evaluation was conducted in the NIOSH Pittsburgh Research Laboratory's Lake Lynn Experimental Mine (LLEM). The purpose of the evaluation was to determine the blast resistance of the CFRP reinforcement technique, designed to increase the strength of two types of existing 20-psi-rated in situ mine ventilation seals.