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Passive explosion barrier for mines
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Patent number 4,284,144
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Issue date Aug 18, 1981
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The United States of America as represented by the Secretary of the Interior
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Israel Liebman
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E21 - EARTH DRILLING MINING
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Trigger device for explosion barrier
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Patent number 4,173,140
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Issue date Nov 6, 1979
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The United States of America as represented by the Secretary of the Interior
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Israel Liebman
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E21 - EARTH DRILLING MINING
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Passive explosion barrier
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Patent number 3,960,217
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Issue date Jun 1, 1976
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The United States of America as represented by the Secretary of the Interior
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Israel Liebman
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E21 - EARTH DRILLING MINING
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Pressure sensitive explosion barrier
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Patent number 3,958,644
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Issue date May 25, 1976
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The United States of America as represented by the Secretary of the Interior
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Israel Liebman
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E21 - EARTH DRILLING MINING