NIOSH Mining Laboratory

Failure of a 4 foot thick cementitious type pumpable seal

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Two large-scale underground chambers in the Lake Lynn Experimental Mine are used to conduct pneumatic, hydrostatic, or explosion pressure loading of candidate seals for Mine Safety and Health Administration (MSHA) approval. Besides serving as a NIOSH research laboratory, the hydrostatic test chambers were designed to demonstrate a less costly alternative to full scale explosion tests and to provide the industry with a test procedure that can be used at individual mine sites for site-specific testing of candidate seals.

The largest chamber is 29.9 ft wide by 15.1 ft high by 10.2 ft deep with a maximum cross-sectional area of 452 ft2. The smaller chamber is 20 ft wide by 7.9 ft high by 10.2 ft deep and can accommodate a seal design with a cross-sectional area up to 158 ft2. Each chamber is connected to a diesel driven air compressor which is used to conduct the pre- and post-explosion leakage measurements and to pressure load seal designs up to 20 psi. A diesel-driven water pump capable of 1000 gpm at 300 psi at the chamber inlet is fed from an underground 130,000 gal reservoir for the hydrostatic tests, and a methane and oxygen injection system is available for conducting methane-air explosion studies. The two chambers are equipped with internal 0-300 psi strain gauge pressure transducers (1000 Hz) for measuring the internal explosion pressure history and an array of spring-loaded linear variable displacement transducers (LVDT) to measure the displacement of the candidate seal. Data are recorded at 2000 (or higher) samples per second per channel with a WINDAQ PC-based data acquisition system.

Site:  Lake Lynn Laboratory

Facility:  Lake Lynn Experimental Mine